USB Arduino into AVR TPI Programmer

Turning an Arduino of virtually any sort into a simple AVR 6-pin ISP programmer is old hat. But when Atmel came out with a series of really tiny AVR chips, the ATtiny10 and friends with only six pins total, they needed a new programming standard. Enter TPI (tiny programming interface), and exit all of your previously useful DIY AVR programmers.

[Kimio Kosaka] wrote a dual-purpose TPI and ISP firmware for the ATmegaxxUn chips that are used as a USB-serial bridge on the Unos, and constitute the only chip on board a Leonardo or Micro. The catch? You’re going to have to do a little bit of fine-pitch soldering. Specifically, [Kosaka-san] wants you to get access to an otherwise obscured signal by drilling out a via. We’d do it just for that alone.

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7 LED’s, 2 Pins – beat that, Charlieplexing

[Tim]’s Dice10 is an exercise in minimalism. Building an electronic dice using an ATtiny10 with code that fits within 1kB is not too difficult. Charlieplexing the LED’s would have used three of the four available GPIO pins. [Tim] upped the game by using just two GPIO pins to drive the seven LED’s for the dice. A third GPIO is used as a touch button input. Besides the ATtiny and the LED’s, the only other component used is a capacitor across the supply inputs.

2 GPIO for 7 LED's
2 GPIO for 7 LED’s

The LED’s are grouped in three pairs of two LED’s and a single centre LED. Usually, Charlieplexed LED’s are connected across pairs of GPIO pins. But his scheme includes connections to the 5V and GND terminals, besides the two GPIO pins. Building a truth table makes it easy to figure out what’s going on.

1     Z   Z   --
2     L   Z   LED 1/2
3     H   Z   LED 3/4
4     Z   L   LED 5/6
5     Z   H   --
6     H   L   LED9
7     L   H   --
8     H   H   --
9     L   L   --

Only the logic states used are listed in the table. It’s possible to add two more LED’s between PB0 and GND and one more anti-parallel with LED9, making a total of 10 LED’s driven by two pins. That’s quite a hack. The important thing here is to have two LED’s in series in the arms that connect to either 5V or GND.

[Tim] has posted  the code and hardware source files on his Github repo, and his blog post has some additional details on how he solved the problem.

If you’re looking for more inspirations on minimal dice designs, check this “PIC powered pair of electronic dice” which uses a PIC 12F629 with five outputs driving a pair of 7 pips to make a dual dice.


If you have a cool project in mind, there is still plenty of time to enter the 1 kB Challenge! Deadline is January 5, so check it out and fire up your assemblers!

New Part Day: ATtiny102 and 104

Atmel put out some new, small microcontroller chips early this year, and we’re just now starting to think about how we’d use them. The ATtiny102 and ATtiny104 (datasheet) sell for about a buck (US) and come in manageable SOIC packages with eight and fourteen pins respectively. It’s a strange chip though, with capabilities that fit somewhere between the grain-of-rice-sized ATtiny10 and the hacker-staple ATtiny25-45-85 series.

The ATtiny104 has a bunch of pins for not much money. It’s got a real hardware USART, which none of the other low-end AVRs do, and it’s capable of SPI in master mode. It has only one counter, but it’s a 16-bit counter, and it’s got the full AVR 10-bit ADC instead of the ATtiny10’s limited 8-bit ADC. The biggest limitation, that it shares with the ATtiny10, is that it has only 1 KB of program flash memory and 32 bytes (!) of RAM. You’re probably going to want to program this beast in assembler.

Read on for more reviews, and check out [kodera2t]’s video review at the end.

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Hackaday Prize Entry: A Minimal ATtiny Voltage And Frequency Counter

Sometimes when you build something it is because you have set out with a clear idea or specification in mind, but it’s not always that way. Take [kodera2t]’s project, he set out to master the ATtiny series of microcontrollers and started with simple LED flashers, but arrived eventually at something rather useful. An ATtiny10 DVM and DFM all-in-one with an i2c LCD display and a minimum of other components.

The DFM uses the ATtiny’s internal 16 bit timer, which has the convenient property of being able to be driven by an external clock. The frequency to be measured drives the timer, and the time it returns is compared to the system clock. It’s not the finest of frequency counters, depending as it does on the ATtiny’s clock rather than a calibrated crystal reference, but it does the job.

The results are shown in the video below, and all the code has been posted in his GitHub repository. We can see that there is the basis of a handy little instrument in this circuit, though with the price of cheap multimeters being so low even a circuit this minimal would struggle to compete on cost.

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Breaking Out The ATtiny10

Atmel’s ATtiny10 is the one microcontroller in their portfolio that earns its name. It doesn’t have a lot of Flash – only 1 kilobyte. It doesn’t have a lot of RAM – only thirty two bytes. It is, however, very, very small. Atmel stuffed this tiny microcontroller into an SOT-23 package, more commonly used for surface mount transistors. It’s small, and unless your ideal application is losing this chip in your carpet, you’re going to need a breakout board. [Dan] has just the solution. He could have made this breakout board smaller, but OSHpark has a minimum size limit. Yes, this chip is very, very small.

Because this chip is so small, it doesn’t use the normal in-system programming port of its larger brethren. The ATtiny10 uses the Tiny Programming Interface, or TPI, which only requires power, ground, data, clock, and a reset pin. Connecting these pins to the proper programming header is easy enough, and with a careful layout, [Dan] fit everything into a breakout board that’s a hair smaller than a normal 8-pin DIP.

The board works perfectly, but simply soldering the ATtiny10 to a breakout board and using it as is probably isn’t the best idea. The reason you use such a small microcontroller is to put a microcontroller into something really, really small like ridiculous LED cufflinks. A breakout board is much too large for a project like this, but SOT23 test adapters exist, and they’re only $25 or so.

Either way, [Dan] now has a very, very small microcontroller board that can fit just about anywhere. There’s a lot you can do with one kilobyte of Flash, and with an easy way to program these chips, we can’t wait to see what [Dan] comes up with.

USB On The ATtiny10

Atmel’s ATtiny10 is their smallest microcontroller in terms of physical size – it’s an SOT-23-6 package, or about the same size as surface mount transistors. The hardware inside this extremely bare-bones; three I/O lines, 1kB of Flash, 32 bytes of RAM, and a reduced AVR core with 16 registers instead of 32. With such a minimal feature set, you would think the only thing this micro would be good for is blinking a LED. You’d be right, but [cpldcpu] can blink a LED with the ‘tiny10 over USB.

The V-USB interface usually requires about 1.5kB of Flash in its most minimal implementation, and uses 50 bytes of RAM. This just wouldn’t do for the ‘tiny10, and although [cpldcpu] is working on a smaller, interrupt-free V-USB, there were still some hurdles to overcome.

The biggest issue with putting code on the ‘tiny10 is its reduced AVR core – on the ‘big’ 32-register core, direct memory access is two words. On the ’10, it’s only one word. AVR-GCC doesn’t know this, and no one at Atmel seems to care. [cpldcpu] worked around this problem using defines, and further reduced the code size by completely gutting V-USB and putting it in the main loop.

It’s not much, but now [cpldcpu] can blink an LED with a ‘tiny10 over USB. If you’re wondering, 96.4% of the Flash and 93.8% of the SRAM was used for this project.

Rickrolling remote control prank

This device is a prank or gag that [Eric Heisler] came up with. It will intercept IR remote control codes and play them back after a bit of a delay. The example he shows in the video (embedded after the break) catches the television power signal from a remote, then sends it again after about thirty seconds. This shuts off the TV and would be extremely annoying if you were unable to find the device. Fortunately (for the victim), [Eric] included a piezo buzzer that Rickrolls after sending each code. Just follow that tune to find the offending hardware.

He chose to use an ATtiny10 microcontroller. It looks like it’s realizing its full potential as the six-pin package use all available I/O to control the IR receiver module, an IR led, and the buzzer. It runs from a coin cell without regulation and the circuit was free-formed on a tiny surface mount breakout board which hosts the microprocessor.