Not an original WARC project but something members discussed on a recent zoom meeting with a view to construction some time over the winter 2020.
Project information available https://github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards/issues/7
Possible kit purchase
If you want to change the programming of your ATU, you need an in circuit programmer. There are many choices, of which the obvious ones are either to but a PicKit3 (there are many clones available on ebay or you can lash out and buy a pucker one) or you can get creative. Remember the old WARC DSP project “WarPIC”? You can read about it here:
Well, part of that project was an In Circuit programmed and debugger called “ICD2”. If you have one of those it will work, but you will need to change its programming voltage and you need the right version of the software. Specifically you need MP Lab version 8. Download version 8.92 from here:
Now, when you connect ICD2, DO NOT INITIALLY CONNECT THE ATU. The PIC on the ATU (PIC16F1938) requires a programming voltage (Vpp) of 8-9V whereas the ICD2 will deliver 12V. Microchip recomment fitting a voltage limiter but there is an easier solution. The ICD2 from the WarPIC project has an preset pot on it that sets the programming voltage, and MPLAB has a test function that reads the voltage and tells you what it is. SO just set it to about 8.5V. Job done.