I have this suspicion that as android phones drop in price, they will become a valuable experimentation platform. For example, a scientist could take a $80 android phone, root it, plug in a solar panel, put it in a glass box, and use it as a data acquisitions platform sending data home on the cell network (or nearby wifi if appropriate).
Forgive my ignorance for I am no board designer, but what is stopping me from dumping all disparate connectors and leaving only 6 USB3 connectors? Wouldn't that simplify board manufacturing?
Everytime I see a laptop or netbook with a modem port or an ethernet port I cry a little.
Another silly question (I am a SW developer not HW) but, can the display port be universally replaced by an USB3 port?
Why yes or why not. Feel free to call me names, I rather take it and learn than surf the waves of ignorance.
I have the opposite experience. I work extensively with SBCs both as a user and a software developer. It is a pain in my butt when there is no ethernet port.
There are a lot of applications where wifi is not a better solution than ethernet. I work on robotics and wifi doesn't make sense. We are pushing a lot of data around in near real time and the SBCs are permanently mounted close together. Why use wifi there? We see better performance (network and power consumption wise) and simpler setup with ethernet. We usually will have a half dozen SBCs on a switch and then in some cases a wifi access point that is optional. When we are debugging in the field we turn on the AP and stream data back to a tablet or netbook to observe, but otherwise it is off.
The other problem with not having connectors on the board is dongle and price creep. If I have 6 SBCs, and each one needs some kind of networking adapter external to it, all of sudden my nice neat solution is a mess of wires. And the price jumps from $89 to $139, multiplied by however many I am using.
Ethernet is cheap and ubiquitous and works well if you need wired networking an ethernet network goes about 300'. There is a signal propagation limit in the usb protocol that makes it unable to go over ~16feet without adding repeaters and there is a max of 5 repeaters.
Q2: Why can't I use a cable longer than 3 or 5m?
A2: USB's electrical design doesn't allow it. When USB was designed, a decision was made to handle the propagation of electromagnetic fields on USB data lines in a way that limited the maximum length of a USB cable to something in the range of 4m. This method has a number of advantages and, since USB is intended for a desktop environment, the range limitations were deemed acceptable. If you're familiar with transmission line theory and want more detail on this topic, take a look at the USB signals section of the developers FAQ.
Q3: How far away from a PC can I put a USB device?
A3: With the maximum of 5 hubs connected with 5m cables and a 5m cable going to your full speed device, this will give you 30m of cable (see section 7.1.19 for details). With a low speed device, you will be able to get a range up to 27m, depending on how long the device's cable is. With a straightforward cable route, you will probably be able to reach out 25m or so from the PC.
All of these different ports you don't want serve a specific purpose. Designing a universal electrical interface and connector that satisfy every purpose would be difficult to impossible, not to mention that having separate interfaces for separate purposes reduces confusion. I'll agree it could be potentially awesome, though. Each design in use has tradeoffs between latency, throughput, distance, resilience to interference, etc.
Ethernet is designed for low-ish latency, moderate bandwidth, and long distances. It does not have enough bandwidth to replace HDMI, and Ethernet routing and addressing is not well-suited to the problems solved by USB. My own testing has shown that 802.11g will not often exceed ~15mbit/s, even with a device sitting right next to the access point. All devices on a wireless network have to share the same 54mbit/s with each other and with any other noise that happens to interfere. Switched Ethernet gives the full bandwidth to all devices, all the time.
HDMI and DVI are designed for direct, zero-latency, high-bandwidth links over medium distances. The current iteration of HDMI specifies a bit rate of 10.2 gigabits per second, over distances up to ~50 feet. It's a one-way interface (for now). Since it's mostly unidirectional, and doesn't have any kind of routing, it could not replace USB. If you added USB-like bus features, it would likely not be fast enough for displays.
USB is designed with a simple master/slave hierarchical bus topology, which is ideal for desktop peripherals. Even USB3 at 5gbit/s isn't enough to replace HDMI, and that 5gbit/s is used for control as well as data, and shared across all devices on a particular interface. Plus, USB cannot exceed 15 feet without repeaters.
USB is also not well-suited to replace PCI(e) for graphics adapters, because PCI(e) allows for very-low-latency communication, DMA, etc.
I think the intent of a board like this is to serve as a means of prototyping devices. The designer doesn't know what the Hawkboard customers will try to build in the long run, so he provides multiple different ports to maximize the utility of the board for prototyping.
In regard to USB3 specifically, it's plenty fast, but it has the major distinction versus Ethernet that it's not bus-addressable, i.e. it has no provisions for network routing. Also, I suspect (but I'm not certain) that its latency is relatively high compared to something like DisplayPort.
Check out also the FOX board that's actually built of a core module (cpu, flash and ram) plus a daughter board that brings out all common interfaces for prototyping (ethernet, usb, rtc, gpio, etc.).
When you've finished prototyping and have your own board you can drop their daughter board and buy just the core for 69 euros.
SoC processors have several built in controllers on the CPU. For instance, you'll typically see: a flash controller, an ethernet controller, one or more UARTs, i2c controller, DRAM controller, etc. Development boards break out all of these controllers to external interfaces.
The OMAP-L138 Processor only supports usb 1.1 and usb 2.0. In general, a fair number of low power processors in the PDA/netbook realm only support usb 1.1. It may be possible to use an external usb 3.0 controller but that would dramatically complicate your board design.
> Forgive my ignorance for I am no board designer, but what is stopping me from dumping all disparate connectors and leaving only 6 USB3 connectors? Wouldn't that simplify board manufacturing?
Industrial, hobby and embedded control are usually a generation or two behind 'mainstream' when it comes to io, also there is usually a need to interface to older devices.
So, yes, board manufacturing would be easier but it would be harder to sell the boards, because those are exactly the markets that these boards are targeted at. They're not 'mainstream' devices, or at least, not until they've been packaged as some kind of appliance.
> Everytime I see a laptop or netbook with a modem port or an ethernet port I cry a little.
An ethernet port ? Those are pretty useful, not all connections to the internet for laptops are using wireless, for instance, many companies will not allow the use of WI-FI on their premises for security reasons, so wiring the laptops is the only option there.
> Another silly question (I am a SW developer not HW) but, can the display port be universally replaced by an USB3 port?
Not yet, but that may happen at some point in the future.
There are a number of competing solutions for the permanent replacement of the display connectors with something more bus like, USB is only one of those.
There are actually plenty of graphics solutions for USB(2). They all use low-key GPUs with not much power in the 3D department, but the ones I have tested have had no problems with true 3D payloads (accelerated, not SW rendering) of the "simpler" kind such as f.e. Quake 1, and of course no problems at all with any normal desktop usage - if it's just software-framebuffer action (which covers like 95% of anything commonly "desktop/office" with the exception of fullscreen video which can stutter at higher framerates and resolutions) they are a pretty cheap and efficient choice for expanding your desktop or laptop with another screen, without giving any notable burden on the CPU for slinging data.
What I meant was for dumping every different kind of connector and use a universal connector for everything. I am not talking about the usefulness or not of ethernet or wifi, both have their places, but I've used usb-to-ethernet adapters and they work well. It is all about the plug size, not the architecture.
Take a look at your mackbook on the side, the two biggest holes are for the modem and ethernet ports. Time to downsize them, not to get rid of them.
So, how difficult is it for manufacturers to get together and join efforts to find solutions for the benefit of all? wait, I have to stop daydreaming about utopia again.
PS.
What I meant again, if you can plug a mouse, printer, camera, mic, etc into a usb port, why not a monitor, ethernet or any other rogue device? I want answers like 'displays use flux-capacitors u dumbass' or 'ethernet uses quantum waves u fucktard therefore blah blah' or is it just manufacturers being dickheads?
Seriously though, USB just doesn't have the right features for certain applications. Not enough bandwidth for good graphics, for one.
Finally, there's the issue of size. Yes, you could have a board with a bunch of USB ports and Ethernet adapters, etc. hanging off that. But you get a smaller device if you integrate your peripherals. On this board the video controller is in the OMAP chip, along with an Ethernet MAC. The board itself is just bringing these out to a physical interface.
We are at a point where throwing more transistors onto a chip and making a built-in Ethernet module is much, much cheaper than manufacturing an extra board and putting it together.
Lately I've been trying to find a low cost (<$50) Linux device to use in a project. My only requirements are Wifi, USB (host), and a small form factor. Don't need a lot of ram/flash/etc or any video output. I've been really surprised by the lack of options. The ASUS WL-520gU is around USD$30 but is a bit too large. The Fonera 2.0g (€35) would be perfect, but it's not available in the US.
Another really cool (tiny!) looking device is the Ubiquiti Ministation, but unfortunately it doesn't have USB and therefore isn't a choice for this project.
This is a nice board, though of course Europeans pay more than Americans, as usual.
Incidentally, LinuxJournal has quite a few advertisers with small Linux boards.
Has anyone found a good source for suitable screens for these small boards? I am not talking about USB2 based displays(which tend to be quite pricey), but precisely screens using more specific ports(DVI-D on Beagle) and VGA here on Hawk.
That is, I am looking for a screen suitable for putting in enclosure with the board.
