Pi AVR Programmer HAT Hookup Guide

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QCPete

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Board Overview

Before we get into using our Pi AVR Programmer HAT, let’s quickly overview what components fill the board out:

2x20 Raspi Header -- This female header will connect down to the GPIO pins on your Raspberry Pi. When pushed all the way down into the GPIO pins, the HAT will sit flush with the top of your enclosure.
Target VCC Select -- Jumpers to choose what logic level you’d like to talk to your target. Options include "TARGET", 3.3V, and 5V.

Note: The "TARGET" option means that the target IC will provide the logic level reference voltage. "TARGET" is the default setting for this jumper. Also note that the 3.3V and 5V options are provided from those voltages on the Raspi 2x20 headers. Please only close one of these jumpers at a time. Closing more than one jumper will damage your Raspi.

Isolation Switch IC -- The multiplexer IC that disconnects the SPI lines from your Pi to the Target.
SPI Interface (1x6 header) -- These headers provide optional direct access to the SPI lines. This is in a 1x6 straight header format, so it will mate nicely with your 6-pin Jumper wire. Most programmers use ribbon cables, which will fail after so many insertions. This 1x6 cable and adapter solution is much more robust. You can also opt to remove the supplied jumper cable, and wire up to your target with your own jumper wires or custom adapter.
SPI Interface Adapter (2x3 header) -- This adapter mates easily with the standard ISP header found on most AVR boards.
Shutdown Button -- Hold this down for 6 seconds to shut down your Pi.

Note: This is simply a momentary button on a GPIO pin. It could be used for other things, but the Python module running the Pi AVR Programmer HAT (test.py) is watching this line to engage a full shutdown of the Pi. After you engage a shut down, please watch the “active” LED on the Raspberry Pi. It is located inside the enclosure next to the power LED. Wait for it to stop blinking, then you can remove power.

Capsense Pad -- Use this to engage programming. Simply tap with your finger and that will trigger the onboard capsense ATQ421010 IC which is connected to a GPIO on the Pi.
Status LEDS -- Used for indicating power, success and/or fail for various stages of programming.
Label Boxes -- These blank white silk-screen boxes are handy for labeling your Pi with a project name and version of your loaded hex file.

AVR ISP Pinouts

AVRs are programmed through an SPI interface. There are six unique signals required for communication between ISP and AVR:

VCC
GND
Reset
MOSI
MISO
SCK

To route those signals between devices, there are two standardized connectors -- one 10-pin, 2x5 connector and another 6-pin, 2x3 connector:

AVR ISP Pinouts -- Top View.

The Pi AVR Programmer HAT includes a 1x6 jumper cable and adapter which terminates with a 2x3 connector. There are labels on the bottom side near each leg on the SMD header:

ISP Adapter -- Top and Bottom View.

If your target device has the 2x5 pinout option, then you could use some of our F/F jumper cables to connect directly from the right-angled 1x6 male header on the HAT PCB to your target.