ihsan kehribar from the Little Wire project informs us of his recent work entitled “Printf style debugging over AVR-ISP pins.” He writes, “if you are breadboarding an AVR chip, you are already using the SPI pins for programming the device; therefore it would be nice to use that cable for low-level debugging also. I wrote an Arduino library for that purpose and it is working! That means, you can set up an Arduino on a breadboard and use the Little Wire as programmer and also console interface for printf style debugging! But, you should tie down the SS pin to the ground as well.”
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