I wanted to make a breakout board for my ATTiny85 that was similar to the the Arduino.
The goal was to make a simple circuit that I could plug an ATTiny85 in to and then attach jumpers to a breadboard in the same way that you can with an Arduino Uno (or it's ilk). This, coupled with an AVRISP, would make prototyping easier. Yeah, there are boards that you can buy on eBay for tuppence-ha'penny, but I didn't make any of them :)
Part of the fun of the whole Arduino/Open Hardware Platform is that you are encouraged to do things yourself ... so I did.
As yet, I haven't connected the SPI headers, but I'll get to that.
The parts for this are very simple, and pretty cheap:
Item Price Qty Cost
Total cost of parts = $1.66 (AUD) with all parts bought from eBay
In terms of the time that it took from concept to completed (so far) is about 4 hours including waiting for glue to dry, acid to etch, iron to warm up, testing and general time wasting.
Step 1: Design the Board
I used Fritzing to design the board. I use Fritzing a lot.
The attached PDF are ready to print.
I have updated the images and PDF on this page as I've made some adjustments to the circuit. The fine traces for the SPI are now gone from the design ... they have to be wired using jumpers now. I'll probably come back to this using a double sided PCB instead of my usual single sided, or just keep going with the jumpers. When I've done that, I'll post another page into this instructable with pictures and a better description.
Step 2: Etch the Board
Well ... this could have gone better ... the fine traces kinda failed, but they are really not thoroughly needed. I plan to replace the failed traces with solid core wire, this will complete the ISP block. At the moment, I need to plug the AVRISP into the breakout sockets that I have supplied ... my main problem is that I didn't break out the Reset pin, but that trace DID work.
I've marked the area that failed to transfer properly and was, consequently, etched away.
Step 3: Populate the board
I trial fitted all of the components so that I would be able to simply sit down and solder.
The order of soldering that I used was:
This worked pretty well for me.
Step 4: Test
Testing is a very practical part of any project.
When testing, I like to break things down into simple steps:
BEFORE YOU INSERT ANY SOCKETS
Now that you have satisfied yourself that the circuit is correctly connected and adequately powered, you can start running your circuit tests (such as LED lights up, chip performs correctly ... and in the case of this circuit, that your IDE can connect to the ATTiny85).
Step 5: Power Up
Now it's time to plan what I'm going to do with my 85Duino ... probably nothing yet ... I'm waiting for my new AVRISP from Adafruit.
I will probably try using the circuit with a blank (but boot loaded) ATTiny85 and connect the circuit to my Arduino and upload a simple (blinky) sketch and then run the sketch with only the power connected to the circuit.
At the moment, the circuit is powered by a 9V battery, I haven't given it a USB connection, but I do have a USB to barrel jack connector that I could use.
Anyway, the circuit is "complete" and tested, all I really need to do now is to connect the SPI block and I'll be away.
Step 6: Jumpers for AVRISP and more testing
Finally, connecting the ATTiny85 to the AVRISP break-out so that I can connect the Adafruit AVRISP to the ATTiny85 for easy uploading of sketches from ATMEL AVRStudio and/or Arduino IDE.
In the pin-out diagram that I've provided, the grey pins on the ATTiny85 are not connected. Each of the coloured pins are the same colour as the jumpers in the photograph.
The hardest part of this was bending the ends of the copper core into little eye hooks to wrap around the underside of the female pin headers ... and it wasn't that hard.
All I can say for this process is that it is a little fiddly because you want to make sure that none of your jumpers make contact with each other.
This is another opportunity to get out your multimeter and do some testing. Once again, you want to test for continuity from the appropriate pins of the ATTiny85 and the pin header for the AVRISP, you ALSO want to then test each of the other pin headers to make sure that there isn't any continuity. Use the following truth table to help ... if you want./ PB5 PB3 PB4 GND PB0 PB1 PB2 VCC MI -- -- -- -- -- Y -- -- SC -- -- -- -- -- -- Y -- RS Y -- -- -- -- -- -- -- GND -- -- -- Y -- -- -- -- MO -- -- -- -- Y -- -- -- 5V -- -- -- -- -- -- -- Y
So you would test MI to each of the pins on the ATTiny85 and ONLY get a continuity positive where you see a Y in the table, you want to get a continuity negative for all other pins.
Well, that concludes this article.
I'm hoping to receive my AVRISP from Adafruit soon ... so that I can use this circuit in anger ;)