As Joerg Wunsch wrote: > I think I've got the connections wired correctly: > > RPi ISP Name > > 19 4 MOSI > 21 1 MISO > 23 3 SCK > 24 5 /RESET > 25 6 GND
I finally understood it. Pin 24 (GPIO8) cannot be used since it belongs to the standard SPI feature set of Linux, where the select signal is deasserted rather quickly, so we would leave ISP mode on the AVR. Thus, an independent GPIO pin needs to be used. Pin 22 (GPIO25) is an obvious option, being quite close to the SPI pins on J8 on the Raspberry Pi. I added an example pinout to the doc/avrdude.texi file. Also, the driver abused the -b <baudrate> option to set the bit clock for ISP operation. This option was meant for (older) RS232-attached programmers as the communication baud rate. I changed it to use -B <bitclock> instead (with a fallback to the -b value), which has the additional benefit that kHz and MHz suffix units are being understood. Also, I changed the default clock from 400 kHz to 200 kHz, as this is IMHO a much more sane default since most AVRs ship with 1 MHz CPU clock by default. Bottom line, I got it working on my Raspberry Pi now. -- cheers, Joerg .-.-. --... ...-- -.. . DL8DTL http://www.sax.de/~joerg/ Never trust an operating system you don't have sources for. ;-)
