2009-12-27
USBtinyISP Programmer
The recent blinkenlight projects have giving me a need for a AVR programmer that will work with my Win32 based laptop so I can fiddle with their scripting in place (especially the larger tree project which just won't fit in the attic lab). I've been meaning to play with WinAVR anyway, it is handy to have a Win32 setup for working with AVRs, especially on the road.
The project is a simple doughnut board implementation of a variant of the USBtinyISP and USBtiny projects.
The wiring pencil made quick work of assembling the circuit. I used my current parallel port programmer to program the Atmel ATtiny2313. I left out the 3v3 clamping zeners as I did not have them in the junkbox, but put 100 Ω resistors in series with D+/D-, this seems to work with my USB ports. I'll likely add them when I get some to keep the signal lines in-spec.
I did not bother to implement the "programmer programming" header option via the ISP header that the USBtinyISP has. I did implement the power control jumpers, letting the programmer run off the external circuit or vice versa. I added protection resistors to all the ISP lines for robustness. Mine also has a 8-pin DIP socket on the board for my current programming ZIF socket adapter (or direct connection of smaller devices) in addition to the standard 6-pin and 10-pin ISP headers. Unlike the original USBtiny project I did not implement a full parallel port D25 (although that is quite tempting as I have many parallel port projects that are deprecated now due to the obsolescence of the parallel port).
Naturally the device works fine under Linux too. In fact it was easier to get working under Linux than Windows.
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