PCB changes and completed instructions

A project log for AVR Programmer for Raspberry Pi

A simple board that lets you use the SPI interface on a Raspberry Pi to program ATMEL AVR microcontrollers.

KevinKevin 01/09/2016 at 07:050 Comments

It has been a while since I last added to the project project log. I've been working on some other projects and I took a bit of a break for the Christmas holidays and new years.

I have just completed work on the instructions section for this project. There have also been additional changes to the PCB layout since I made my last project log entry.

While I was working on adding the last few items to the instructions section I thought of having an option to provide either 3.3V or 5V to external circuit but decided it was too dangerous. If the external circuit was being separately powered by 5V and the programmer board was set to provide 3.3V the external 5V power would get fed back to the 3.3V rail of the Raspberry Pi which would ruin the Pi.

The other thought that came to mind while finishing the notes for the instructions section was to make it easier to use the unused buffers in the 74LVC245. That resulted in additional changes to the PCB. I moved the resistors and the '245 to allow room for pads to allow access to the unused inputs of the '245. I then had to widen the board by 0.05" to make room for a header to be installed in the new pads and allow for the use of a socket for the '245. I think the PCB is now done and won't need any further changes, but I've thought that before while working on another PCB.

The last thing I still need to do related to this project is make my updated version of avrdude_gui available for download.