Or for $10, you could get the TI MSP430 LaunchPad [1]. You can then pop off the DIP chip and mount it however you want. It is nice since the chips themselves are about $1 or so each (depending on which one you get).
I rather like the new board but since we're talking low-cost alternatives one thing to consider is buying Arduino-compatible boards directly from China.
My personal experience with boards roughly the size of the Trinket has been as follows: I have purchased a Pro Micro [1] compatible with an ATmega32U4 chip and an on-board MicroUSB port from a Chinese seller on eBay for under $9 as well as two no-name Arduino Pro Mini variants with ATmega328 chips from two different eBay sellers for around $4 each, all fully working. At their price point the latter can compete with ATtiny85 chips directly despite being noticeably more powerful and more convenient to use in many cases. I can't say much about the long-term reliability of those boards (my guess is that if you buy enough of them you'll notice that on average it isn't that great compared to that of boards with officially sourced MCUs) but the ones I got for myself and acquaintances (different models, six total) work as specified for now. The oldest one is over a year old and has been used in several different projects including one that ran continuously for 160+ hours.
My experience with the launchpad has been mixed. The chips are definitely aimed at the low power, low requirements side of things; I had a project where the MSP430g2231's inability to clock from an external high-frequency crystal was a dealbreaker. There's also a wider breadth of hobbyist software targeting the AVR.
If you're a hobbyist, it's definitely not worth saving a few bucks if you're only making a few of them and you account for the value of your time. YMMV.
While it can't use an external xtal, it still has an internal crystal oscillator which can clock it at some MHz, up 16 MHz I think. It's not as accurate but cheaper and more flexible. I did a port of the Contiki OS to the Launchpad, which now comes with the msp430g2452 (16kB flash/256 B RAM) and the 'g2553 (16/512). At home I have them using cc2500-radios (2$ modules from aliexpress) and a radio duty cycling protocol I wrote, with plenty of flash space left for user applications.
I was under the impression that the newer chips are able to clock from an external crystal. My 2553 certainly came with one, though I have had no need to use it yet.
This has 8 more pins than the LaunchPad and is a bit cheaper: https://analog10.com/store/BOB-G2553-28.html You can drive motors from those pins while keeping your P1 free for comm peripherals.
Looks somewhat inspired by the teensy 2.0 (mini USB -- not micro!, bootloader button). This has a lower price point and an ATTiny instead of atmega32u4. I have a few teensys and find them to be really practical.
Does the ATTiny implement USB or is it bit-banged?
Good question. The type USB implementation is important. There are lots of things you can't do well if the CPU is managing the USB connection in firmware at the same time as running the implementation.
Limor (and the company she built) has been producing microcontroller and Arduino kits & boards like this for a long time. Digispark reflects a lot of her original work. This is a good thing!
Many people don't find this exciting. But I am excited indeed. You know why? Because to program an Atmel Microcontroller, you need a 'programmer' whose selection itself is fairly confusing for newbies (USB/Serial/etc) and costs as much as $20 for a good one. This one instead is just plug and play, and that's awesome :)
The Arduino platform has already largely solved that, though. Almost all of their products (besides a few "Pro" models which are TTL-serial only) have USB ports on board.
Yes, but (at least in New Zealand) they're more than the $20 threshold mentioned above. So you're effectively buying a microcontroller plus a programmer.
Why didn't they use the ATmega 8u2 with native USB? The small version is no bigger than the chip on this trinket. Eating 3 kB for the tinyUSB stack is annoying.
Also, they claim is has "hardware I2C" which is stretching the truth IMO. The USI doesn't let you write a fully interrupt driven I2C slave, it is a polled implementation leaving lots of support logic to software.
Well the interesting things probably involve using the SPI port to talk to some memory expansion.
At Google, Henner Zeller built a circuit pretty much like this that drove an RGB LED and was used for Test status 'orbs'. Basically with a bit of code your orb would turn red if your tests started failing in the continuous build.
I used one to add a foot 'key' to my setup when playing World of Warcraft (it was my push to talk switch) but it could have been anything, it pretended to be a USB keyboard with one key :-).
I've seen them used to pretend to be a mouse and move the mouse around (a 'jiggler') so that a machine wouldn't kick in the screen saver.
All various sorts of things you might want to do with a bit of compute.
Head over to http://hackaday.com or http://makezine.com and search for Arduino or ATMega or microcontroller -- you should have a ton of hits describing various projects.
Probably not very. The Arduino uses hardware serial and a USB-to-serial chip to communicate with the PC, whereas this has no hardware serial or USB-to-serial at all and is missing various peripherals.
Compared to an Arduino, this is smaller, consumes less power and has a "standard" layout and costs about 1/3rd of an "official" Arduino. The downsides are that there's less memory and less cpu perf, there are less I/O pins, but a lot of (practical, non-beginner) projects don't need that many pins. A highlight would be hardware SPI and I2C support, which are communication protocols for small gadgets (the AVR chip in Arduino has I2C/SPI but you can't use it from Arduino code, you need to write C) and PWM (pulse width modulation) which is a pseudo-analog output signal used to control things like servos.
So what could it be used for? Get a bunch of sensors and actuators that communicate with SPI/I2C/PWM. Think about things like accelerometers, gyroscopes, proximity sensors, liquid crystal displays, motor controllers, servo motors. Now plug them together and build just about any gadget you can imagine.
It's better than an Arduino if you're short on space, weight or power consumption. Things like tiny flying machines or wearable gadgets.
If you're a beginner looking for your first microcontroller platform, the Arduino will probably be easier to approach.
The ATtiny series do not have USB capability, which is why they are cheaper. The underlying bitbang implementation comes from V-USB [1], which is commonly used to add USB capability in software. Another implementation which may be of interest is LUFA [2].
This board is pretty minimalistic. It has five general-purpose I/O pins that you can use to read and write logic-level signals (either 0V or your supply voltage, usually either 3.3V or 5V). Three of those also have analog-to-digital converters, so you can use them to measure voltages in that whole range. Two of these pins have hardware for generating PWM signals, making them useful for motor control. Three of these can be used for an SPI or I2C bus.
By itself at can't do those. If you connect it to a WiFi or Zigbee module using SPI it can, but for WiFi you'll probably want to buy a more powerful microcontroller board anyway.
No one seems to have mentioned the Minimus[1] as an arduino compatible[2] alternative -they we're costing us £3 and have a lot more GPIO pins to play with[3]. The new version is powered by a ATMEGA 32U2 so it's got some grunt (and lets you play USB too).
One obvious advantage is that it's cheap enough to use as-is. One of the things that keeps me from caring much about Arduino is that it's too expensive to use for anything but experimentation: if I'm building more than a one-off, I'll always do a custom PCB.
For reasonable volumes that's still probably the best approach, but at $8 a pop this is perfect for throwing together some quick project.
By way of analogy: to me, an Arduino is a breadboard. If I use one at all, it's to play with a first concept, and certainly not for any kind of permanent use. If that's true, then this is kind of like solderable perfboard: not optimal, but good enough for many things.
It's a relatively huge amount of power in a tiny package, ready to roll. Many digital logic tasks that used to take a number of TTL/CMOS logic chips, or other devices can now be done in one inexpensive package.
A simple example: every week it seems, on the electronics forums, someone will ask how to do a simple, or a complex timing task and they will be pointed at various logic, or 555 timer chip designs.
Using something like this not only makes those projects simple, it provides a common frame of reference. If I can say to someone "go buy a Trinket from Adafruit and load this code into it and it will work cause I already tested it on my workbench" that provides a tremendous value because both I and the person I'm talking to online are working from a common platform.
I got excited about this thinking I could use it to quickly prototype controlling a toaster oven over USB, but I'd have to add another software USB implementation like the bootloader's.
They're really cheap, which makes them really easy to just put into things. It's also a great way of getting people to think-outside-the-arduino.