Computing stuff tied to the physical world

ATtiny 8-pin ISP programmer

In AVR, Hardware on May 1, 2010 at 00:01

Yesterday’s ISP programmer used a 28-pin socket wired up for ATmega328 chips (and the older 48/88/168 versions).

As it turns out there are enough unused pins available in that socket to also support the ATtiny 8-pin series (such as 25/45/85). The trick is to add a few extra wires so that the ISP programming signals have the proper setup for these smaller chips as well:

Dsc 1376

This allows placing an ATtiny in the socket at the top end, i.e. using just pins 1..4 and 25..28:

Dsc 1377

This trick works, because the I/O pins used by the ATtiny happen to be normal I/O pins for the ATmega, so it doesn’t mind having some logic signals there (pins 9..12 and 17..20 can probably also be used, but then inserting the chip becomes more error-prone).

And sure enough, avrdude can now program the ATtiny as well:

Screen Shot 2010 04 25 at 02.44.46

For other chips, you’ll need to wire up a chip-specific socket, but at least for these ATtiny chips an ATmega setup will work just fine!

  1. That is excactly what i was searching for! A board for most types of AVRs would be even better but this way i can flash at least the most common chips if use…

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