As I said in the project information, this project has three phases. First, redesign the circuit to work with the Raspberry Pi. Second, make a PCB design for the new circuit. Third, modify the original BattMan II software to work on the Pi.

These tasks could be done sequentially, but I have been working on all of them at various times.

I have kept the modifications of the original circuit to a minimum, because it is simple, elegant, and it works. I have replaced the logic chips with 74HCT versions as they run at 5V but can accept 3.3V signals as input. The CD4050 hex buffer is not available as an HCT part, so I am using a 74HCT125 quad buffer instead. I have built this part of the circuit to test it and it works.

The PCB design is ready but I have not exhaustively inspected it. I used KiCAD to draw the schematic, and I haven't had any problems using it for the PCB layout. I chose to build the circuit with through-hole parts, like the original, but the board size is the same as the Raspberry Pi HAT specification (but without the EEPROM). I intend that the board will fit on top of the Pi, with the heatsink and fan on top of the USB socket area. I also included a jumper to allow the Pi to power the 5V devices in the circuit, or for the 7805 regulator to power the Pi (in case you want to use a Pi Zero).

The software is a little tricky. It is written in Borland C++ for Windows, but I want to convert it to Python. I have chosen TKinter for the GUI, and I have written code for the three windows (main, setup and start), and a module which controls the hardware attached to the GPIO pins. I am converting each module slowly from the original code, and changing things to be a little more Pythonic, and to fit in with the TKinter architecture.

Everything will be put on my github for playing or collaboration. Thanks for reading.