gz_arduino waveform

This core is programmed in a straight through configuration.

When sel is low, it passes the arduino programming signals, miso, mosi, sclk and rst straight through from the equivalent pins on the Raspberry Pi. When sel is high, rst is high and the miso, mosi and sclk signals are tri-stated.

From the perspective of the Raspberry Pi, this design works exactly the same way as programming the ATMega chip on a Gertboard. See Gordon Henderson's most excellent tutorials here.

This core was tested using what is called a bare bones arduino. The diavolino is less than $12. It has no power supply, and no USB interface. Neither of these is a problem for this design. You can take 5 volt power from the GuzuntyPI board and the ATMega328P is programmed through the in circuit programming interface (ICSP). Communication with it is possible through SPI using the same core by moving just one wire from pin 5 of the ICSP to pin 3 of J3 on the arduino board. Serial communication is also possible but would require some reconfiguration of the Guzunty; connect JP32 and JP34 (also recommend disconnecting JP29 and JP30 if you want to keep all Pi signals off the Guzunty connectors).