I’m very happy to announce that I managed to get the Automatic Magnetic Loop Tuner project code running on a Teensy 4.0. So far it seams everything still works, but extensive test are still needed.
The biggest hurdles that needed to be taken were the different way the serial port of the Teensy 4.0 works and the ADC who has only 10 bit available (instead of 12). Tests will need to prove if this loss in precision (from 4096 samples to 1024 samples is a reduction of 4:1) is an issue or not, and if it can be tackled rewriting the code, or making better use of the more advanced hardware the Teensy 4.0 is over the Teensy 3.2
Also the analogue pins on the back of the Teensy 4.0 are SMD pads. Although A10 and A11 are available, these are both ADC0. To be able to measure the SWR correctly, I needed both ADC0 and ADC1. Hence I switched to A12. Don’t mind the residual blob of solder on A11 😉
Next item on the to-do list is to create a new version of the PCB to have a better connection of both A10 and A12 pads. I’m still figuring out whether to use pogo-pins, SMD header-pins, or just as I did here, solder a short piece of wire.