This is very exciting! For the last several years I have been developing a brushless motor driver based on the RP2040 [1]. The driver module can handle up to 53 volts at 30A continuous, 50A peak. I broke the driver out to a separate module recently which is helpful for our farm robot and is also important for driver testing as we improve the design. However this rev seems pretty solid, so I might build a single board low cost integrated single motor driver with the RP2350 soon! With the RP2040 the loop rate was 8khz which is totally fine for big farm robot drive motors, but some high performance drivers with floating point do 50khz loop rate.
My board runs SimpleFOC, and people on the forum have been talking about building a flagship design, but they need support for sensorless control as well as floating point, so if I use the new larger pinout variant of the RP2350 with 8 ADC pins, we can measure three current signals and three bridge voltages to make a nice sensorless driver! It will be a few months before I can have a design ready, but follow the git repo or my twitter profile [2] if you would like to stay up to date!
I have given some thought to a two-wheeled electric tractor for dealing with mud -- horse paddocks turn into basically a 1-foot deep slurry after heavy rain and it can be easier to deal with something small that sinks through the mud, down to solid ground than something using large floatation tires. Additional problem with large tires is that they tend to throw mud around, making everyone nearby even more dirty.
I haven't actually built anything (been paying attention to Taylor's work, though), but I came to the same conclusion that bike wheels & tires would probably be a good choice. It also doesn't hurt that we have many discarded kids' bikes all over the place.
I’m curious there. I’ve seen rice paddies plowed in Vietnam and the tractors used wide paddle-like wheels. I saw two varieties: one with what looked like more normal wheels but much wider, and one which was of metal with fins, very much akin to a paddle steamer, though still with some kind of flat surface that must have distributed weight.
Would they be more effective with thin wheels? Both humans and cattle seem to sink in a few inches and stop; I don’t know what’s under the layer of mud and what makes up a rice paddy.
> Borrowed from just-as-weird French "piquer" - to stab or jab.
Literally «piquer» means “to sting” or “to prick” more than stab or jab, it's never used to describe inter-human aggression.
And piquer is colloquially used to mean “to steal” (and it's probably the most common way of using it in French after describing mosquito bites)
Edit: and I forgot to mention that we already use it for curiosity, in fact the sentence “it piqued my curiosity” was directly taken from French «ça a piqué ma curiosité».
All this reminds me of the now-famous quote about English "borrowing" words...
> The problem with defending the purity of the English language is that English is about as pure as a cribhouse whore. We don't just borrow words; on occasion, English has pursued other languages down alleyways to beat them unconscious and rifle their pockets for new vocabulary.
It is kind of funny that both of the incorrect versions, peaked or peeked, sort of make more sense just based on the definitions of the individual words. “Peaked my interest” in particular could be interpreted as “reached the top of my interest.”
Way better than stabbing my interest, in a French fashion or otherwise.
I think it makes more sense if you consider the expression "this tickles my fancy".
Why do we use "tickle" there? Because a tickle is a type of stimulation, and "fancy" here means "interest", so one is effectively saying "this stimulates my interest".
If we then consult Oxford Language's definition of pique, we find:
> stimulate (interest or curiosity). "you have piqued my curiosity about the man"
The word "piqued" in "this piqued my curiosity" serves as something along the lines of:
stimulated, aroused, provoked
This is aligned with the French word "piquer", as a "prick" or "sting" (much like a tickle) would stimulate/arouse/provoke.
Right, but that meaning isn’t quite right. To pique your interest is to arouse it, leaving open the possibility that you become even more interested, a possibility which peaking of your interest does not leave open.
However, in the case where someone means "This interested me so much that I stopped what I was doing and looked up more information," peaked is almost more correct, depending on how one defines "interest" in this context (eg. "capacity for interest"? probably no; "current attention"? probably yes).
>I have been developing a brushless motor driver based on the RP2040
Can I ask why? There's dedicated MCU for BLDC motor control out there that have the dedicated peripherals to get the best and easiest sensored/sensorless BLDC motor control plus the supporting application notes and code samples. The RP2040 is not equipped to be good at this task.
During the chip shortage, specialized chips like this were very hard to find. Meanwhile the RP2040 was the highest stocked MCU at digikey and most other places that carried it. The farm robot drive motors don't need high speed control loops or anything. We just needed a low cost flexible system we could have fabbed at JLCPCB. The RP2040 also has very nice documentation and in general is just very lovely to work with.
Also SimpleFOC was already ported to the RP2040, so we had example code etc too. Honestly the CPU was the easy part. As we expected, getting a solid mosfet bridge design was the challenging part.
Hah thats right. I did get some parts to try to update the other one you are referring to, but given all my projects it has not made it near the top of the queue yet.
i am not a engineer type of person but to even thing that someone is trying to create a motor is really impressive. When i was a kid , i used t break my toy cars and would get motors from it and felt like i really did something. good ol' days.
The motor controller is impressive, but it sounds like a motor controller (as it says), rather than a motor. That is, it's not mechanical, it's electrical, it sends inputs to the motor telling it when to turn the individual magnets on and off. That is a nontrivial challenge since it has to monitor the motor speeds under varying loads and send pulses at exactly the right time, but it's software and electronics, not machinery.
I can't imagine someone using an RP2040 in a real product, but the RP2350 fixes enough of my complaints that I'd be really excited to give it a shot.
There's a lot going for the 2040, don't get me wrong. TBMAN is a really cool concept. It overclocks like crazy. PIO is truly innovative, and it's super valuable for boatloads of companies looking to replace their 8051s/whatever with a daughterboard-adapted ARM core.
But, for every cool thing about the RP2040, there was a bad thing. DSP-level clock speeds but no FPU, and no hardware integer division. A USB DFU function embedded in boot ROM is flatly undesirable in an MCU with no memory protection. PIO support is extremely limited in third-party SDKs like Zephyr, which puts a low ceiling on its usefulness in large-scale projects.
The RP2350 fixes nearly all of my complaints, and that's really exciting.
PIO is a really cool concept, but relying on it to implement garden-variety peripherals like CAN or SDMMC immediately puts RP2350 at a disadvantage. The flexibility is very cool, but if I need to get a product up and running, the last thing I want to do is fiddle around with a special-purpose assembly language. My hope is that they'll eventually provide a library of ready-made "soft peripherals" for common things like SD/MMC, MII, Bluetooth HCI, etc. That would make integration into Zephyr (and friends) easier, and it would massively expand the potential use cases for the chip.
These examples are cute, but this isn't a comprehensive collection. Not even close.
Given that PIO's most compelling use case is replacing legacy MCUs, I find it disappointing that they haven't provided PIO boilerplate for the peripherals that keep those archaic architectures relevant. Namely: Ethernet MII and CANbus.
Also, if RP2xxx is ever going to play ball in the wireless space, then they need an out-of-box Bluetooth HCI implementation, and it needs sample code, and integration into Zephyr.
I speak as someone living in this industry: the only reason Nordic has such a firm grip on BLE product dev is because they're the only company providing a bullshit-free Bluetooth stack out of the box. Everything else about nRF sucks. If I could strap a CYW4343 to an RP2350 with some example code as easily as I can get a BT stack up and running on an nRF52840, I'd dump Nordic overnight.
Well open source CAN and MII implementations do exist. Perhaps you can help provide a pull request to the official repo that checks in appropriate versions of that code, or file an issue requesting them to do it.
My biggest issue with their wireless implementation is that I get my boards made at JLCPCB and Raspberry Pi chose a specialty wireless chip for the Pico W which is not widely available, and is not available at JLCPCB.
I feel like the PIO is just slightly too limited for that. You can already do some absolute magic with it, but it's quite easy to run into scenarios where it becomes really awkward to use due to the limited instruction count, lack of memory, and absence of a direct clock input.
Sure, you can work around it, but that often means making significant sacrifices. Good enough for some hacking, not quite there yet to fully replace hard peripherals.
You run into issues if you try to implement something like RMII, which requires an incoming 50MHz clock.
There's an implementation out there which feeds the clock to a GPIO clock input - but because it can't feed the PLL from it and the PIO is driven from the system clock that means your entire chip runs at 50MHz. This has some nasty implications, such as being unable to transmit at 100meg and having to do a lot of postprocessing.
There's another implementation which oversamples the signal instead. This requires overclocking the Pico to 250MHz. That's nearly double the design speed, and close to some peripherals no longer working.
A third implementation feeds the 50MHz clock into the XIN input, allowing the PLL to generate the right clock. This works, except that you've now completely broken the bootloader as it assumes a 12MHz clock when setting up USB. It's also not complete, as the 10meg half duplex mode is broken due to there not being enough space for the necessary PIO instructions.
Almost correct - the third implementation does generate the clock, but it isn't necessary to drive the clock directly from the system clock, as there are m/n clock dividers available. I use a 300 MHz system clock, and divide down to 50 MHz which works well. (I've also addressed a few other shortcomings of this library, but am not done yet...) Haven't looked at the 10 MHz half duplex mode, though.
Do you have your code publicly available? I was just discussing with a friend it would be nice to add an optional Ethernet mode to my motor controller, but the limitations of this library or other approaches limit the appeal.
Also, are there any other approaches that might be better and would offer 100meg or even gigabit links with the RP2350? Thanks!
I'm still working on it - hopefully will be on the DECstation2040 github soon. The interface uses the LAN8720/8740 MAC chips, which provide 10/100 Mbit. (I haven't tried 10 Mbit, so no idea if it works or not). FYI, here's a test result:
ping -q -i 0.005 192.168.1.6
PING 192.168.1.6 (192.168.1.6) 56(84) bytes of data.
229501/229501 packets, 0% loss, min/avg/ewma/max = 0.063/76.725/88.698/160.145 ms
295393/295987 packets, 0% loss, min/avg/ewma/max = 0.063/76.792/37.003/160.171 ms
295393/296278 packets, 0% loss, min/avg/ewma/max = 0.063/76.792/37.003/160.171 ms
(Above is with killall -s QUIT ping)
As you can see, it eventually hangs, and CMSIS reports:
target halted due to breakpoint, current mode: Handler HardFault
xPSR: 0x61000003 pc: 0x200001c4 msp: 0x20040f40
As far as I understood the explanation, the incoming ("external") 50Mhz clock signal is a core requirement of the spec: all of those workarounds are just what is required to meet that spec, and be able to TX/RX using the protocol at all.
Oh, I'm sure it's great for industrial, as long as you can live with the hardware security issues. In college, my first serious task as an intern was to take a Cortex-M0+ and make it pretend to be an 8051 MCU that was being obsoleted. Unsurprisingly, this was for an industrial automation firm.
I mimicked the 16-bit data bus using hand-written assembly to make sure the timings were as close as possible to the real chip. It was a pain in the ass. It would have been amazing to have a chip that was designed specifically to mimic peripherals like that.
It's great that there's a community growing around the RPi microcontrollers! That's a really good sign for the long-term health of the ecosystem they're trying to build.
What I'm looking for is a comprehensive library of PIO drivers that are maintained by RPi themselves. There would be a lot of benefits to that as a firmware developer: I would know the drivers have gone through some kind of QA. If I'm having issues, I could shoot a message to my vendor/RPi and they'll be able to provide support. If I find a bug, I could file that bug and know that someone is going to receive it and fix it.
>>> extremely limited in third-party SDKs like Zephyr
So is almost any non-trivial peripheral feature. Autonomous peripheral operation, op-amps, comparators, capture/compare timers…
Zephyr tries to provide a common interface like desktop OSes do and this doesn't really work. On desktop having just the least common denominator is often enough. On embedded you choose your platform because you want the uncommon features.
I haven’t dug into the RP2xxx but I presumed there would be a library of PIO implementations of the standard protocols from RP themselves. There really isn’t?
Edit: I see, there are “examples”. I’d rather have those be first-class supported things.
> I can't imagine someone using an RP2040 in a real product
Why not? It's a great chip, even if it has some limitations. I use it in several of my pro audio products (a midi controller, a Eurorack module, and a series of guitar pedals). they are absolutely perfect as utility chips, the USB stack is good, the USB bootloader makes it incredibly easy for customers to update the firmware without me having to write a custom bootloader.
I've shipped at least a thousand "real" products with an RP2040 in them.
Given the way the RP2040 is set up, I cannot conceive of a proper secure boot chain for it. So, for basically everything I work on professionally, it's a non-starter. I think the key in your use case is that "hackability" is a feature, not a potentially life-threatening risk.
Not only that, the single FP and double FP were provided as optimized subroutines. I was never hampered by inadequate FP performance for simple control tasks.
It's certainly useful, but having it embedded within the hardware with no way to properly secure it makes the RP2040 a non-starter for any product I've ever written firmware for.
For my work, the lack of flash memory integration on the 2040 is a deal breaker. You cannot secure your code. Not sure that has changed with the new device.
It has: you can encrypt your code, store a decryption key in OTP, and decrypt into RAM. Or if your code is small and unchanging enough, store it directly in OTP.
I guess you are very serious about competing with industrial MCU’s.
We had to use a 2040 shortly after it came out because it was impossible to get STM32’s. Our customer accepted the compromise provided we replaced all the boards (nearly 1000) with STM32 boards as soon as the supply chain normalized.
I hope to also learn that you now have proper support for development under Windows. Back then your support engineers were somewhat hostile towards Windows-based development (just learn Linux, etc.). The problem I don’t think they understood was that it wasn’t a case of not knowing Linux (using Unix before Linux existed). A product isn’t just the code inside a small embedded MCU. The other elements that comprise the full product design are just as important, if not more. Because of this and other reasons, it can make sense to unify development under a single platform. I can’t store and maintain VM’s for 10 years because one of the 200 chips in the design does not have good support for Windows, where all the other tools live.
Anyhow, I explained this to your engineers a few years ago. Not sure they understood.
I have a project that I could fit these new chips into, so long as we don’t have to turn our workflow upside down to do it.
I will when I get a break. I'll bring-up our old RP2040 project and see what has changed.
I remember we had to use either VSC or PyCharm (can't remember which) in conjunction with Thonny to get a workable process. Again, it has been a few years and we switched the product to STM32, forgive me if I don't recall details. I think the issue was that debug communications did not work unless we used Thonny (which nobody was interested in touching for anything other than a downloader).
BTW, that project used MicroPython. That did not go very well. We had to replace portions of the code with ARM assembler for performance reasons, we simply could not get efficient communications with MicroPython.
Thanks again. Very much a fan. I mentored our local FRC robotics high school team for a few years. Lots of learning by the kids using your products. Incredibly valuable.
I was reading in I believe the Register article that yes, that's one of the protections they've tested... will be interesting to see if anyone can break it this month!
You can certainly do that, sure, but any Cortex-M MCU can do that, and plenty of others have hardware AES acceleration that would make the process much less asinine.
Also, 520K of RAM wouldn't be enough to fit a the whole application + working memory for any ARM embedded firmware I've worked on in the last 5 years.
To my recollection, every piece of Cortex-M firmware I've worked on professionally in the last 5 years has had at least 300K in .text on debug builds, with some going as high as 800K. I wouldn't call anything I've worked on in that time "atypical." Note that these numbers don't include the bootloader - its size isn't relevant here because we're ramloading.
If you're ram-loading encrypted firmware, the code and data have to share RAM. If your firmware is 250K, that leaves you with 270K left. That seems pretty good, but remember that the 2040 and 2350 are dual-core chips. So there's probably a second image you're loading into RAM too. Let's be generous and imagine that the second core is running something relatively small - perhaps a state machine for a timing-sensitive wireless protocol. Maybe that's another 20K of code, and 60K in data. These aren't numbers I pulled out out of my ass, by the way - they're the actual .text and .data regions used by the off-the-shelf Bluetooth firmware that runs on the secondary core of an nRF5340.
So now you're down to 190K in RAM available for your 250K application. I'd call that "normal," not huge at all. And again, this assumes that whatever you're running is smaller than anything I've worked on in years.
> Also, 520K of RAM wouldn't be enough to fit a the whole application + working memory for any ARM embedded firmware I've worked on in the last 5 years.
what are you smoking? I have an entire decstation3100 system emulator that fits into 4K of code and 384bytes of ram. I boot palmos in 400KB of RAM. if you cannot fit your "application" into half a meg, maybe time to take up javascript and let someone else do embedded?
I'm smoking multiprotocol wireless systems for industrial, medical, and military applications. To my recollection, the very smallest of those was around 280K in .text, and 180K in .data. Others have been 2-3x larger in both areas.
I would sure hope a decstation3100 emulator is small. After all, it's worthless unless you actually run something within the emulator, and that will inevitably be much larger than the emulator itself. I wouldn't know, though. Believe it or not, nobody pays me to emulate computers from 1978.
So you make hardware costing dozens of thousands of dollars and brag about memory on 5$ chip?
That explains a lot why so many medical and industrial (I haven’t touch military hardware) are so badly designed, with some sad proprietary protocols and dead few months after warranty passes. Today I’ve learned!
Not sure why this is downvoted but the sleep and dormant pico examples have quite some issues, they are still in "extras" and not in "core", so while documentation of features is my personal favorite aspect of the pico, there is room for improvement here still.
It is downvoted because it is a low effort sarcastic comment which provides no real contribution to the discussion. Your comment actually provides real feedback as to where there are currently issues.
Even if it does I'm suspicious. The open source RISC-V verification systems are not very good at the moment:
* riscv-arch-tests: ok, but a very low bar. They don't even test combinations of instructions so no hazards etc.
* riscv-test: decent but they're hand-written directed tests so they aren't going to get great coverage
* TestRig: this is better - random instructions directly compared against the Sail model, but it's still fairly basic - the instructions are completely random so you're unlikely to cover lots of things. Also it requires some setup so they may not have ran it.
The commercial options are much better but I doubt they paid for them.
Be careful with assumptions though. Being 5V tolerant doesn't mean that your 3V output can sufficiently drive an input that expects 0-5V levels correctly.
I ran into this problem using an ESP32 to drive a Broadcom 5V LED dot-matrix display. On paper everything looked fine; in reality it was unreliable until I inserted an LS245 between the ESP and the display.
> Being 5V tolerant doesn't mean that your 3V output can sufficiently drive an input that expects 0-5V levels correctly.
It's fine for TTL (like your 74LS245 is), which registers voltages as low as 2V as a logical 1. Being able to directly interface with TTL eases up so many retrocomputing applications.
A better question might be why anyone is using a MAX7219 on a new design in 2024. There are so many other choices for displays than a 20 year-old IC from a company that's gone through two changes of ownership since.
Anyway, a 74LS245 isn't a level shifter, it's an octal buffer. It just happened to be the right choice for my needs. In your application, I'd suggest an actual level shifter. You can find level shift breakout boards at Sparkfun and Adafruit.
I'm having trouble seeing where the datasheet actually says the GPIO pins are 5V tolerant.
EDIT: okay, section 14.8.2.1 mentions two types of digital pins: "Standard Digital" and "Fault Tolerant Digital", and the FT Digital pins might be 5V tolerant, it looks like.
Yep, I edited a few minutes ago to mention a reference I found in the datasheet. It's cool, but the reality seems a little more nuanced than that quote would indicate, since that only appears to work for GPIO-only pins, not just pins being used as GPIO. (So, if a pin supports analog input, for example, it will not be 5V tolerant.)
You're right, after re-reading the Power section on the datasheet it seems connecting 5V to the VREG_VIN should suffice to power the digital domains, but if you want to use the ADC, you still need a external 3.3V source.
The chip needs a) 1.1V to power the cores, b) 1.8V-3.3V to power IO, and c) 3.3V to properly operate USB and ADC.
The chip has one onboard voltage regulator, which can operate from 2.7V-5.5V. Usually it'll be used to output 1.1V for the cores, but it can be used to output anything from 0.55V to 3.3V. The regulator requires a 3.3V reference input to operate properly.
So yeah, you could feed the regulator with 4-5V, but you're still going to need an external 5V->3.3V converter to make the chip actually operate...
I'd rather have it run on the lower voltage - generally easier to step down than buck up. Either way, the modules are pretty cheap, small, and easy to find.
The regulator can take that, but as far as I can see it's only for DVDD, the core voltage of 1.1 V. You also need at least IOVDD, which should be between 1.8 V and 3.3 V. So you'll need to supply some lower voltage externally anyway.
I suppose the main draw of the regulator is that the DVDD rail will consume the most power. 1.1 V is also much more exotic than 3.3 V.
Big day for my team (Pigweed)! Some of our work got mentioned in the main RP2350/Pico2 announcement [1] but for many months we've been working on a new end-to-end SDK [2] built on top of Bazel [3] with support for both RP2040 and RP2350, including upstreaming Bazel support to the Pico SDK. Our new "Tour of Pigweed" [4] shows a bunch of Pigweed features working together in a single codebase, e.g. hermetic builds, on-device unit tests, RPC-centric comms, factory-at-your-desk testing, etc. We're over in our Discord [5] if you've got any questions
Pretty awesome. I love Bazel and it seems you're making good use of it. It's such a difference seeing everything hermetically integrated with all workflows boiling down to a Bazel command.
We realize Bazel is not the right build system for every embedded project. The "Bazel for Embedded" post that came out today (we co-authored it) talks more about why we find Bazel so compelling: https://blog.bazel.build/2024/08/08/bazel-for-embedded.html
In my experience, Bazel is great if you are a Google-sized company that can afford to have an entire team of at least 5-10 engineers doing nothing but working on your build system full time.
But I've watched it be insanely detrimental to the productivity of smaller companies and teams who don't understand the mountain of incidental complexity they're signing up for when adopting it. It's usually because a startup hires an ex-Googler who raves about how great Blaze is without understanding how much effort is spent internally to make it great.
Thanks for the discussion. What was the timeframe of your work in these Bazel codebases (or maybe it's ongoing)? And were they embedded systems or something else?
I have to admit, Bazel as a build system would mean it wouldnt even be considered by me, it has to fit in with everything else which typically means Makefiles, like it or not.
TBH, Java + Bazel + Discord makes it seem like its out of step with the embedded world.
You can pick either ARM cores or RISC-V cores on the same die? Never saw design like this before. Will this impact price and power consumption?
"The Hazard3 cores are optional: Users can at boot time select a pair of included Arm Cortex-M33 cores to run, or the pair of Hazard3 cores. Both options run at 150 MHz. The more bold could try running one RV and one Arm core together rather than two RV or two Arm.
Hazard3 is an open source design, and all the materials for it are here. It's a lightweight three-stage in-order RV32IMACZb* machine, which means it supports the base 32-bit RISC-V ISA with support for multiplication and division in hardware, atomic instructions, bit manipulation, and more."
Apparently (this is news to me), you can also choose to run 1+1 Arm/RISC-V, you don't have to switch both cores either/or.
Eben Upton: "They're selectable at boot time: Each port into the bus fabric can be connected either to an M33 or a Hazard3 via a mux. You can even, if you're feeling obtuse, run with one of each."
yeah lockstep requires a whole bunch of things to verify and break deadlocks. I suspect you need three processors to do that as well (so you know which one has fucked up.)
It is not necessary that there is triple modular redundancy with lockstep, I know of microcontrollers with two processors, who throw an error when the results from instructions don't match.
We did look at this, but the AHB A-phase cost of putting a true arbiter (rather than a static mux) on each fabric port was excessive. Also, there's a surprising amount of impact elsewhere in the system design (esp debug).
Yea, i was hoping for 2+2 myself but I suspect it's because the setup doesn't have the ability to mediate peripherals between the cores in a way that'd let that work. I.e. trying to turn on both Risc-v and arm #1 cores means that there'd be bus conflicts. It'd be cool if you could disable the io on the risc-v cores and do all hardware io through arm (or vice versa) so you can use the unconnected ones for just pure compute tasks (say run ws2812b led strips with the arm cores but run python/javascript/lua on the risc-v cores to generate frames to display without interrupting the hardware io).
This "switchable cores" thing has been appearing in some products for a few years now, for example Sipeed SG2002 (LicheeRV). The area occupied by the actual instruction core is usually pretty small compared to peripherals and internal memories.
This seems like a great way to test the waters before a potential full-on transition to RISC-V. It allows to validate both technically and market reception, for a much lower cost than taping out a additional chip.
I really hope people don't do this. Or at least not try to sell it as ARM vs RISC-V tests.
Because what you are really testing is the Cortex-M33 vs the Hazard 3, and they aren't equivalent.
They might both be 3 stage in-order RISC pipelines, but Cortex-M33 is technically superscalar, as it can dual-issue two 16bit instructions in certain situations. Also, the Cortex-M33 has a faster divider, 11 cycles with early termination vs 18 or 19 cycles on the Hazard 3.
If you ignore the FPU (I think it can be power gated off) the two cores should be roughly the same size and power consumption.
Dual issue sounds like it would add a bunch of complexity, but ARM describe it as "limited" (and that's about all I can say, I couldn't find any documentation). The impression I get is that it's really simple.
Something along the line of "if two 16 bit instructions are 32bit aligned, and they go down different pipelines, and they aren't dependant on each other" then execute both. It might be limitations that the second instruction can't access registers at all (for example, a branch instruction) or that it must only access registers from seperate register file bank, meaning you don't even have to add extra read/write ports to the register file.
If the feature is limited enough, you could get it down to just a few hundred gates in the instruction decode stage, taking advantage of resources in later stages that would have otherwise been idle.
According to ARM's specs, the Cortex-M33 takes the exact same area as the Cortex-M4 (the rough older equivalent without dual-issue, and arguably equal to the Hazard3), uses 2.5% less power and gets 17% more performance in the CoreMark benchmark.
That is exactly what the "limited dual issue" is - two non-conflicting pre-decoded instructions (either 16b+16b or if a stall has occurred) can be sent down the execution pipe at the same time. I believe that must be a memory op and an ALU op.
I do wonder if the unavailability of some of the security features and -- possibly a big deal for some applications -- the accelerated floating point on the RISC-V cores would skew that experiment, though.
Indeed, though I'm curious about the rationale behind it. It is a 'plan B' in case their relationship with ARM sours? It is aiming for cost-cutting in the future (I can't imagine the ARM licences are costing them much given the price of the RP2040, but maybe they're absorbing it to get marketshare)
I think it's cool as a cucumber that we can choose fully open-source RISC-V if we want. My guess is the RV cores are slower clock-per-clock than the M33 cores; that is benchmark scores for M33's will be better, as Hazard3 is only 3-stage pipeline - but so is M33. Can't wait for the benchmarks.
Of course I did. If you also did, you would know that they do in fact have 64 megabyte PSRAMs as I stated. So a helpful comment would have been "they're not compatible, though". Your reply as it stands just makes it sound like you maybe assumed that I don't know the difference between megabits and megabytes.
A USB-C port that only supports USB2 data and power only needs a few resistors across some pins to trigger legacy modes and disable high current/voltage operation. All the extra bits are the things that jack up the cost.
USB3 and altmodes require extra signal lines and tolerances in the cable.
High-voltage/current requires PD negotiation (over the CC pins AFAIK)
Data and power role swaps require muxes and dual-role controllers.
That's all the stuff that makes USB-C a pain in the ass, and it's all the sort of thing RPi Nanos don't support.
You're confusing USB C and USB 3.1+. USB C is just the physical spec. You can design a cheap device that will only support USB 2 if you just connect ground, Vbus, D+ and D- and gasp add two resistors. It will work just as well as the micro-usb plug.
completely valid, but i would like to think the org is still designing for accessibility for newbies in mind.
like you said, the connector does not have to follow the standards. i have seen hdmi ports being used to carry pcie signal (not a good like but here is one such device https://pipci.jeffgeerling.com/cards_adapter/pce164p-no6-ver...) amgon other things. it is still non-standard behaviour.
How about connections not becoming flaky after you've plugged in the cable a few times. Micro USB was horribly unreliable. USB-C isn't great either, but it's an improvement. Maybe they will get it right some day.
I always hear that but I never had a micro usb fully fail on me but my phone's usb-c are lint magnets and get super loose and refuse to work. When that happened on micro it was usually the cable tabs a bit worn but the cable always worked.
FWIW the Pimoroni Tiny 2040 and Tiny 2350 use usb-c, but as mentioned by other commenters, the cost for these usb-c boards is higher.
I love having usb-c on all my modern products, but with so many micro-usb cords sitting around, I don't mind that the official Pico and Pico 2 are micro-usb. At least there are options for whichever port you prefer for the project you're using it in.
USB-C is way more complicated, even if you're not trying to push 4K video or 100W power through it. The interface chip ought to be more complex, and thus likely more expensive.
You can still find a number of cheap gadgets with micro-USB on Aliexpress. Likely there's some demand, so yes, you can build a consumer product directly on the dev board, depending on your customer base.
Yes, indeed, I've checked, and apparently you don't need anything beyond this if you don't want super speed or power delivery (past 5V 3A).
I did not realize how many pins in a USB-C socket are duplicated to make this possible. (For advanced features, you apparently still need to consider the orientation of the inserted cable.)
For the microcontroller however, the use in commercial products is encouraged.
There are one-time programmable registers for Vendor, Product, Device and Language IDs that the bootloader would use instead of the default.
It would be interesting to see if those are fused on the Pico 2.
USB-C doesn't require anything special USB wise as it's decoupled from the versioned standard. It just has more pins and works with all modern cables. Ideally the cables won't wear out like Mini and Micro and get loosey goosey in the ports.
Yep, a USB-C connector is more or less a drop in replacement for MicroUSB if you don’t need USB3 or USB-PD. With one aggravating exception: it requires adding two 5.1kΩ pulldown resistors to be compatible with C-C cables. Thus signaling to a charger that the sink is a legacy non-PD device requesting 5V.
Which is apparently an impossible ask for manufacturers of dev boards or cheap devices in general. It’s slightly more understandable for a tried and true dev board that’s just been connector swapped to USB-C (and I’ll happily take it over dealing with Micro) but inexcusable for a new design.
My hope is Apple going USB-C only on all their charging bricks and now even C-C cables for the iPhone will eventually force Chinese OEMs to build standard compliant designs. Or deal with a 50% Amazon return rate for “broken no power won’t charge”.
For a device, USB-C requires two resistors that older USB ports don't.
Declaring yourself as a host/device is also a bit different: USB-C hardware can switch. Micro USB has a "On-the-go" (OTG) indicator pin to indicate host/device.
The USB PHY in RP2040 and the RP2350 is actually capable of being a USB host but the Micro USB port's OTG pin is not connected to anything.
Hm, I've used mine as a USB host with an adapter? Not sure of the details, I suppose OTG is the online/runtime switching and I was just running as fixed host?
It's a bit surprising that they put so much effort into security for the second microcontroller from a young consumer-oriented* company. My first instinct was to distrust it's security, simply due to lack of experience. However, the "experienced" vendors' secure micros have lots of known security bugs and, more crucially, a demonstrated desire to sweep them under the rug. Two security architecture audits, a $10k bug bounty, and designing a board for glitching as the DEF CON badge shows a pretty big commitment to security. I'm curious about how the Redundancy Coprocessor works. I still wouldn't be surprised if someone breaks it, at least partially.
* By perception at least. They have been prioritizing industrial users from a revenue and supply standpoint, it seems.
Can’t find an official announcement or datasheet yet, but according to this post:
* 2x Cortex-M33F
* improved DMA
* more and improved PIO
* external PSRAM support
* variants with internal flash (2MB) and 80 pins (!)
* 512KiB ram (double)
* some RISC-V cores? Low power maybe?
Only $1 more than the original Pico, that's an absolute steal. Although the Pico2 doesn't have PSRAM onboard so there's room for higher end RP235x boards above it.
Make one in an Arduino Uno form factor and double the price and they'd make a killing :-)
I try to dissuade n00bs from starting their arduino journey with the ancient AVR-based devices, but a lot of the peripherals expect to plug into an Uno.
Well there's the UNO-R4 Renasas I suppose, but this would be much cooler indeed. There's also the 2040 Connect in the Nano form factor with the extra IMU.
Downside is it occupies a CS on the QSPI controller, presumably bonding to the same pads as the QSPI pins on the package, so now you only have one external memory IC. It's a very small tradeoff all things considered, but is still technically a tiny disadvantage over highly integrated MCUs.
A potential alternative would have been a directly memory-mapped NOR flash die, but that would have required more bond wires, more dedicated pads on the die, a port on the bus, and on top of that the memory die would have been more expensive too.
An older (and often impractical) alternative is to use a single die with both flash and SoC on, in the same process. This usually forces a larger-than-desired process node to match the flash technology, making the SoC take up more space. The result requires no extra bond wires or pads, but now you're really manufacturing a flash chip with an MCU attached.
Can someone explain the benefit of having essentially 4 cores (2 ARM + 2 RISC-V) on the chip but only having 2 able to run simultaneously? Does this take significantly less die space than having all 4 available at all times?
I see a business decision here.
Arm cores have licensing fees attached to them.
Arm is becoming more restrictive with licensing and wants to capture more value [1]:
> The Financial Times has a report on Arm's "radical shake-up" of its business model. The new plan is to raise prices across the board and charge "several times more" than it currently does for chip licenses. According to the report, Arm wants to stop charging chip vendors to make Arm chips, and instead wants to charge device makers—especially smartphone manufacturers—a fee based on the overall price of the final product.
Even if the particular cores in the RP2350 aren't affected, the general trend is unfavorable to Arm licensees.
Raspberry Pi has come up with a clever design that allows it to start commoditizing its complement [2]:
make the cores a commodity that is open-source or available from any suitable RISC-V chip designer instead of something you must go to Arm for.
Raspberry Pi can get its users accustomed to using the RISC-V cores—for example, by eventually offering better specs and more features on RISC-V than Arm.
In the meantime, software that supports the Raspberry Pi Pico will be ported to RISC-V with no disruption.
If Arm acts up and RISC-V support is good enough or when it becomes clear users prefer RISC-V, Raspberry Pi can drop the Arm cores.
Coordinating access to the memory bus and peripherals is probably not easy to do when the cores weren’t ever designed to work together. Doing so could require a power/performance penalty at all times, even though most users are unlikely to want to deal with two completely different architectures across four cores on one microcontroller.
Having both architectures available is a cool touch. I believe I criticized the original RP2040 for not being bold enough to go RISC-V, but now they’re offering users the choice. I’ll be very curious to see how the two cores compare… I suspect the ARM cores will probably be noticeably better in this case.
They actually let you choose one Cortex-M33 and one RISC-V RV32 as an option (probably not going to be a very common use case) and support atomic instructions from both cores.
All of the public mentions of this feature that I've seen indicated it is an either/or scenario, except the datasheet confirms what you're saying:
> The ARCHSEL register has one bit for each processor socket, so it is possible to request mixed combinations of Arm and RISC-V processors: either Arm core 0 and RISC-V core 1, or RISC-V core 0 and Arm core 1. Practical applications for this are limited, since this requires two separate program images.
Beyond the technical reasons for the limit, it provides for a relatively painless way to begin to build out/for RISC-V[1] without an uncomfortable transition. For those who just want a better next iteration of the controller, they have it. For those who build tools, want to A/B test the architectures, or just do whatever with RISC-V, they have that too. All without necessarily setting the expectation that both will continue to coexist long term.
[1] While it's possible they are envisioning dual architecture indefinitely, it's hard to imagine why this would be desirable long term esp. when one architecture can be royalty free and the other not, power efficiency, paying for dark silicon etc.
cores are high bandwidth bus masters. Making a crossbar that supports 5 high bandwidth masters (4x core + dma) is likely harder, larger, and higher power than one that supports 3.
It's actually 10 masters (I+D for 4 cores + DMA read + DMA write) versus 6 masters. Or you could pre-arbitrate each pair of I and each pair of D ports. But even there the timing impact is unpalatable.
Each arm/riscv set likely share cache and register space (which takes most of the die space by far), resulting in being unable to use them both simultaneously.
Considering that these are off-the-shelf Cortex-M designs I doubt that Raspi was able or would be allowed to do that. I'd expect most of the die to be the 512K SRAM, some of the analog and power stuff and a lot of it just bond pads.
Lots of nice improvements here. The RISC-V RV32I option is nice -- so many RV32 MCUs have absurdly tiny amounts of SRAM and very limited peripherals. The Cortex M33s are a biiig upgrade from the M0+s in the RP2040. Real atomic operations. An FPU. I'm exited.
Many people seem excited about the FPU. Could you help me understand what hardware floating point support is needed in a MCU for? I remember DSPs using (awkward word-size) fixed point arithmetic.
I think you highlight the exact issue rather well... fixed-point DSP instructions are awkward to use. The FPU and the double-precision hardware with its baked operations work with IEEE floats out of the box, so the programmer can be "lazy." A thousand new programmers can write something like `* 0.7` in C++ inside a tight loop without it stealing 200 instructions from the timing of the rest of the program.
4 variants? "A" and "B" variants in QFN60 and QFN80, "2350" and "2354" variants with and without 2MB Flash. CPU can be switched between dual RISC-V @ 150MHz or dual Cortex-M33 @ 300MHz by software or in one-time programming memory(=permanently).
Datasheet, core switching details, most of docs are 404 as of now; I guess they didn't have embargo date actually written in `crontab`.
I'm most excited for the partition and address translation support - partitions can be mapped to the same address for A/B boot slots (and it supports "try before you buy" to boot into a slot temporarily). No more compiling two copies for the A and B slots (at different addresses)!
Of course it they'd used Ibex https://github.com/lowrisc/ibex the RISC-V core we develop and maintain at lowRISC that would have been even better but you can't have everything ;)
I see CMSIS definitions for the RP2040 at https://github.com/raspberrypi/CMSIS-RP2xxx-DFP but none for RP2350. Maybe they'll eventually appear in that repo, given its name is RP2xxx? I thought vendors are legally obligated to provide CMSIS definitions when they license an ARM core.
Aha, the 3 is for M33, not Cortex M3 (as some speculated based on the name). That makes a lot more sense! Integrated FPU is a big improvement over the RP2040, and M33 is a modern but proven core.
I presume the article was edited to change its headline after it was submitted to HN, but it's interesting that it doesn't match up with the HN title. It's still a subjective but positive title, but somehow feels like it has a different tone to the title on HN:
HN: "I got almost all of my wishes granted with RP2350"
Article: "Why you should fall in love with the RP2350"
Can anyone speak about plans for a Pico 2 W (or Pico W 2)? I've been playing around recently with mine and even just syncing with the current time over wifi opens up a lot of possibilities.
How difficult would be emulating an old SRAM chip with an RP2040 or an RP2350? It's an early 80s (or older) 2048 word, 200ns access time CMOS SRAM that is used to save presets on an old Casio synth. It's not a continuous memory read, it just reads when loading the preset to memory.
I did that, not just SRAM but also ROM, to fool a MC68EZ328 successfully. It works well. PIO + DMA does it well. Specifically i replaced rom & ram in an old Palm Pilot with an RP2040:
Thought I had more than this, but it's been literally decades...
I found (1) HM6116, (4) HM65256's (1) HM6264 and wonder of wonders, a Dallas battery-backed DS1220, although after 20+ years the battery is certainly dead. All in DIP packages of course.
And a couple of 2114's with a 1980 date code! that I think are DRAM's.
If any of this is useful to you, PM me an address and I'll pop them in the mail.
What is the process node used? Who is fabbing this for them? Given that the new chip is bigger, my guess is the same (old) process node is being used. RP2040 is manufactured on a 40nm process node.
Whoops, I read the fine print: RP2350 is manufactured on a 40nm process node.
Unless the USB-C connector costs $7-10, these are beyond ridiculously overpriced compared to the official dev board. At least throw in an IMU or something if you plan to sell low volumes at high prices jeez.
The cheapest one I've seen so far is the XIAO RP2350, which is $5, same as the official Pico board. I'm sure there will be more cheap options once more Chinese manufacturers get their hands on the chips, no-name USB-C RP2040 boards are ridiculously cheap.
Do you live in a universe where micro-USB cables are not available, or something? There's gonna be something or other that needs micro-USB for the next decade, so just buy a few and move on. They're not expensive.
[later edit: I bet it has to do with backwards compatibility. They don't want people to need to rework case designs to use something that is meant as a drop-in replacement for the Pi Pico 1.]
> Do you live in a universe where micro-USB cables are not available, or something? There's gonna be something or other that needs micro-USB for the next decade, so just buy a few and move on. They're not expensive.
I live in a universe where type C has been the standard interface for devices for years, offering significant advantages with no downsides other than a slightly higher cost connector, and it's reasonable to be frustrated at vendors releasing new devices using the old connector.
It's certainly not as bad as some vendors of networking equipment who still to this day release new designs with Mini-B connectors that are actually officially deprecated, but it's not good nor worthy of defending in any way.
> I bet it has to do with backwards compatibility. They don't want people to need to rework case designs to use something that is meant as a drop-in replacement for the Pi Pico 1.
Your logic is likely accurate here, but that just moves the stupid choice back a generation. It was equally dumb and annoying to have Micro-B instead of C on a newly designed and released device in 2021 as it is in 2024.
The type C connector was standardized in 2014 and became standard on phones and widely utilized on laptops starting in 2016.
IMO the only good reason to have a mini-B or micro-B connector on a device is for physical compatibility with a legacy design that existed prior to 2016. Compatibility with a previous bad decision is not a good reason, fix your mistakes.
Type A on hosts will still be a thing for a long time, and full-size type B still makes sense for large devices that are not often plugged/unplugged where the size is actually a benefit, but the mini-B connector is deprecated and the micro-B connector should be.
It's not a huge deal, but it's still a very strange choice on a product released in 2024.
Pretty much everyone has a USB-C cable lying around on their desk because they use it to charge their smartphone. I probably have a Micro-B cable lying around in a big box of cables somewhere, last used several years ago. Even cheap Chinese garbage comes with USB-C these days.
Sure, Micro-B is technically just fine, but why did Raspberry Pi go out of their way to make their latest product more cumbersome to use?
Personally I have about three dozen USB-A to USB-C cables lying around and the thought of actually spending money to acquire extra Micro USB cables in 2024 is very unappealing.
I (deliberately) haven’t bought a consumer electronic device that still uses Micro USB in years so don’t accumulate those cables for free anymore like with USB-C.
Of course ubiquitous USB-C dev boards/breakout boards without 5.1kΩ resistors for C-C power is its own frustration ... But I can tolerate that having so many extra USB-A chargers and cables. Trigger boards are great because they necessarily support PD without playing the AliExpress C-C lottery.
> I (deliberately) haven’t bought a consumer electronic device that still uses Micro USB in years so don’t accumulate those cables for free anymore like with USB-C.
I guess you’re not gonna be buying a Pi Pico 2, then. So why are you complaining about something you aren’t going to use?
Even if you interpreted that sentence right, that's not a reasonable rebuttal. If a feature stops someone from buying a product, then it makes sense to complain about the feature. Their non-purchase doesn't invalidate the complaint. It's only when someone isn't interested in the category at all that complaints lose their value.
I think you misread what I wrote: consumer electronic device
Dev boards or niche specialized hardware are about the only thing I've willingly bought with Micro USB in 4+ years. As much as I try to avoid it given my preference for USB-C, sometimes I don't have a good alternative available.
> So why are you complaining about something you aren’t going to use?
Because it looks like a great upgrade to my RP2040-Zero boards that I would like to buy but I really dislike the choice of connector? What is wrong with that?
This is fantastic news. Is there information on power consumption?
This is something that precludes a good deal of use cases for the RP2040 unfortunately and any improvements here would be good, but maybe the RP's are just not made for ultra low power?
Significant improvements to flat-out power (switcher vs LDO) and to idle power (low quiescent current LDO for retention). Still not a coin-cell device, but heading in the right direction.
> 1 × USB 1.1 controller and PHY, with host and device support
Sure, after integrating USB 2.0 HS or 1Gb-Ethernet the pico2-board will cost more than $5. So, integrated high-speed interfacing with PC was not a nice-to-have option (for special chip flavor)?
RP1 I/O chip on RPi5 has so many high-speed interfaces. I've been thinking RP2350 could be some smart I/O chip for a PC/notebook/network attached computers (with only 1 necessary high-speed connection).
> I got almost all of my wishes granted with RP2350
I got all mine, these guys really listened to the (minor) criticisms of the RP2040 on their forums and knocked them out of the ball park. Cant wait to get my hands on real hardware. Well done guys
Cortex-M33 timings aren't documented, but one of our security consultants has made a lot of progress reverse engineering them to support his work on trace stacking for differential power analysis of our AES implementation. I've asked him to write this up to go in a future rev of the datasheet.
No official 48 GPIO board, I think: this is slightly intentional because it creates market space for our partners to do something.
This has 2 of the 3 features (float support, faster clock) + more POI that was keeping me on ESP32. For projects that need wifi, and can tolerate the random interrupts, I'll stick with ESP32.
While I completely agree with the content of the post, I still think that QFN packages in general, and RP2350's in particular, are very hobbyist-averse.
Moving all GND pins to the bottom pad makes this chip usable only by people with a reflow oven. I really hoped to see at least a version released as (T)QFP.
Isn't the hobbyist solution to just build a board to which you can attach an entire pico board? That does preclude some things and adds $3, but it makes for a pretty easy prototyping path.
Hard disagree. A TQFP package this dense is still quite challenging for a hobbyist. Just use a breakout board, dev board or get the QFN assembled for you at jlcpcb
> > I was not paid or compensated for this article in any way
> However the Raspberry Pi engineer in question WAS compensated for the samples, in the form of a flight over downtown Austin in Dmitry's Cirrus SR22.
Hahah, I’ve been in that plane. Only in my case, it was a flight to a steak house in central California, and I didn’t actually do anything to get “compensated”, I was just at the right place at the right time.
Anyway, I am extremely excited about this update, RPi are knocking it out of the park. That there is a variant with flash now is a godsend by itself, but the updates to the PIO and DMA engines make me dream up all sorts of projects.
I suppose this isn't the first time a company that started out as a hobbiest board manufacturer produced really amazing micro controllers but man is it insane how far they've knocked the ball out of the park.
I wonder what other uses people will find for it. It's one-way data transfer, I wonder if it could be hooked up to a USB 2.0 or USB 3.0 peripheral, or an ethernet PHY, or something else.
Pretty sure I'm going to link it up with an FPGA at some point - as long as the data is unidirectional, this is a promise of 2400 Mbit/sec - which for a $1 microcontroller is insane. If it overclocks like the processor, you're up to 4800 MBit/sec ... stares into the distance
I can use PIO in the other direction, but this has DDR, so you'll never get the same performance. It's a real shame they didn't make it bi-directional, but maybe the use-case here is (as hinted by the fact it can do TMDS internally) for DVI out.
If they had make it bidirectional, I could see networks of these little microcontrollers transmitting/receiving at gigabit rates... Taken together with PIO, XMOS would have to sit up straight pretty quickly...
Right? Bidirectional capability at those speeds would be incredible for the price of this chip.
Either way, still looking forward to see what people cook up with it, and hopefully I'll find a use for it as well. Maybe combine it with some cheap 1920x1080 portable monitors to have some beautiful dashboards around the house or something...
1920x1080 30 Hz DVI would require running RP2350 at least at 311 MHz ((1920 * 1080 * 30Hz * 10) / 2). Probably a bit more to account for minimal horizontal and vertical blanking etc. Multiplier 10 comes from 8b10b encoding.
To fit in 520 kB of RAM, the framebuffer would need to be just 1 bpp, 2 colors (1920 * 1080 * 1bpp = 259200 bytes).
From PSRAM I guess you could achieve 4 bpp, 16 colors. 24-bit RGB full color would be achievable at 6 Hz refresh rate.
I guess you might be able to store framebuffer as YUV 4:2:0 (=12 bits per pixel) and achieve 12 Hz refresh rate? The CPU might be just fast enough to compute YUV->RGB in real time. (At 1920x1080@12Hz 12 clock cycles per pixel per core @300 MHz.)
(Not sure whether the displays can accept very low refresh rates.)
I think it's a good way to introduce these chips, and it's a great project, but the author's (frankly weird) beef with STM32H7 is detracting from the point they're trying to make:
> So, in conclusion, go replan all your STM32H7 projects with RP2350, save money, headaches, and time.
STM32H7 chips can run much faster and have a wider selection of peripherals than RP2350. RP2350 excels in some other dimensions, including the number of (heterogenous) cores. Either way, this is nowhere near apples-to-apples.
Further, they're not the only Cortex-M7 vendor, so if the conclusion is that STM32H7 sucks (it mostly doesn't), it doesn't follow that you should be instead using Cortex-M33 on RPi. You could be going with Microchip (hobbyist-friendly), NXP (preferred by many commercial buyers), or a number of lesser-known manufacturers.
1. Nobody has a wider selection of peripherals than a chip with 3 PIOs.
2. And my beef is personal - I spent months (MONTHS of my life) debugging the damn H7, only to find a set of huge bugs in the main reason I had been trying to use it (QSPI ram support), showed it to the manufacturer, and had them do nothing. Later they came back and, without admitting i was right about the bugs, said that "another customer is seeing same issues, what was the workaround you said found?" I told them that i'll share the workaround when they admit the problem. Silence since.
I fully reserve the right to be pissy at shitty companies in public on my website!
FlexIO is (I think) powerful, however... I'm not sure if it's me or the way they describe it with all the bit-serialisers/shifters interacting - but I grok the PIO assembly a damn sight easier than FlexIO.
[edit: I retract this, I see you’ve had secretly in your possession to play with for over a year. You lucky dog. ]
> I have been anti-recommending STM’s chips to everyone for a few years now due to STM’s behaviour with regards to the clearly-demonstrated-to-them hardware issues.
You certainly reserve the right. However it is unclear to me why the recommendation to complaints over a months-long period is a product that has just been released.
Trying to ask in a very unbiased way since as a hobbyist I’m looking into ST, Microchip, and RP2040. For my part I’ve had two out of four RP2040 come to me dead on arrival, as part of two separate boards from different vendors - one being Pi Pico from Digilent. Not a ton of experience with Microchip but I hear they have their own problems. Nobody’s perfect, the question is how do the options compare.
they're complaining now because they still feel the pain now. while writing the article, they're thinking of how things would have been different on previous projects if they had had this chip, and that is digging up pain and they felt it should be expressed.
I don't know what's so unclear. Have you never had a strong opinion about someone else's stuff? Man, I have.
I'm not arguing you can't be angry with them, I'm just saying that to me, it detracts from the point about the new platform. Regarding #1, I'm sure you know that peripherals in the MCU world mean more than just digital I/O. Further, even in the digital domain, the reason PIO isn't more popular is that most people don't want to DIY complex communication protocols.
ST is a zillion dollar company that should be hiring the talent capable of delivering product that match the features in their sales pamphlets.
Integration is tricky but a company with STs deep pockets should be able to root cause or at least help troubleshoot an issue, not ask for a fix like some nepotism hire.
I'm not an ST fanboy and they're not a vendor I use, but they are very popular in the 32-bit Cortex-M space, so they're clearly doing something right. Meanwhile, companies like Microchip that put effort into accessible documentation and tooling are getting table scraps.
As other posters have mentioned, this has 2 Cortex-M33 cores @ 150 MHz, not @ 300 MHz.
Cortex-M7 is in a different size class than Cortex-M33, it has a speed about 50% greater at the same clock frequency and it is also available at higher clock frequencies.
Cortex-M33 is the replacement for the older Cortex-M4 (while Cortex-M23 is the replacement for Cortex-M0+ and Cortex-M85 is the modern replacement for Cortex-M7).
While for a long time the Cortex-M MCUs had been available in 3 main sizes, Cortex-M0+, Cortex-M4 and Cortex-M7, for their modern replacements there is an additional size, Cortex-M55, which is intermediate between Cortex-M33 and Cortex-M85.
TFA states extensive 300Mhz OC with no special effort (and he's been evaluating pre-release versions for a year).
"It overclocks insanely well. I’ve been running the device at 300MHz in all of my projects with no issues at all."
Also
"Disclaimer:
I was not paid or compensated for this article in any way. I was not asked to write it. I did not seek or obtain any approval from anyone to say anything I said. My early access to the RP2350 was not conditional on me saying something positive (or anything at all) about it publicly."
The STM32H7 and other M7 chips have caches - performance is night and day between 2x300MHz smaller, cacheless cores and chips with L1 caches (and things like TCM, etc.)
The SRAM in that H7 is running at commensurately-high speeds, as well.
Comparing an overclocked 2xM33 to a non-overclocked M7 is also probably a little inaccurate - that M7 will easily make more than the rated speed (not nearly as much as the RP2040 M0+, though.)
I guess it depends whether you store to X (or Y), normalize & round (NRDD; is it really necessary after each addition?) and load X back every time.
Both X and Y have 64 bits of mantissa, 14 bits of exponent and 4 bits of flags, including sign. Some headroom compared to IEEE 754 fp64 53 mantissa and 11 bits of exponent, so I'd assume normalization might not be necessary after every step.
The addition (X = X + Y) itself presumably takes 2 cycles; running coprocessor instructions ADD0 and ADD1. 1 cycle more if normalization is always necessary. And for the simplest real world case, 1 cycle more for loading Y.
Regardless, there might be some room for hand optimizing tight fp64 loops.
Edit: This is based on my current understanding of the available documentation. I might very well be wrong.
I wish there was a way to share memory with a Pi. The PIO looks great for high speed custom IO, but 100Mb scale interface to/from it is quite hard/unsolved.
I'm assuming you've looked at the pico-rmii-ethernet library? If so, I feel your pain - I've been fixing issues, and am about halfway done. (This is for the DECstation2040 project, available on github). Look for a release in late aug/early sep. (Maybe with actual lance code? Dmitry??) The RP2350 will make RMII slightly easier - the endless DMA allows elimination of the DMA reload channel(s).
I looked at it and dismissed it as too hacky for production. I don't remember the real reason why. I would have to look through my notes. The main question is whether the RP2350 will change that. As in it actually possible to do bug free without weird hacks.
Hmm, it's really nice that they fixed so many complaints. But honestly, reading the errata sheet, I had to chuckle that Dmitry didn't tear this chip to pieces.
I mean, there's erratums about obscure edge cases, about miniscule bugs. Sure, mistakes happen. And then there's this: Internal pull-downs don't work reliably.
Workaround: Disconnect digital input and only connect while you're reading the value. Well, great! Now it takes 3 instructions to read data from a port, significantly reducing the rate at which you can read data!
I guess it's just rare to have pull-downs, so that's naturally mitigating the issue a bit.
In terms of security features, it lacks on-the-fly external memory (flash and PSRAM) encryption and decryption as ESP32 and some newer STM32s did.
Decrypting by custom OTP bootloader and running entirely in the internal SRAM maybe sometimes limited for larger firmware.
Easiest would be to wire up two chips with bidirectional links and use a fault handler to transfer small blocks of memory across. You're reimplementing a poor man's MESIF https://stackoverflow.com/questions/31876808.
says the guy with engineering samples and creme of the creme silicon parts... i expect most that will actually be available when they do to their normal schedule of scraping the literal bottom of the barrel to keep their always empty stocks that will not be the case.
My board runs SimpleFOC, and people on the forum have been talking about building a flagship design, but they need support for sensorless control as well as floating point, so if I use the new larger pinout variant of the RP2350 with 8 ADC pins, we can measure three current signals and three bridge voltages to make a nice sensorless driver! It will be a few months before I can have a design ready, but follow the git repo or my twitter profile [2] if you would like to stay up to date!
[1] https://github.com/tlalexander/rp2040-motor-controller
[2] https://twitter.com/TLAlexander