This is the PSU used on the LoRa/GPS Hat to allow switching the units on/off. The signal EnGPS connects to a GPIO pin and the MCU must pull it high for GPS to switch on – very simple.
One of the functions of a modern EDA is to check schematics and PCB. This works excellent and have saved me lot of work in the past, but I guess it would work even better if I remembered to switch in on. In this case I have somehow managed to switch checking for signal Logic off.
The error here is that I have forgotten to connect these signals on the PCB, so the PSU’s are constantly off. The automatic check would have warned me about this, but as I somehow have switched “signal logic” check off it did not. I made and ordered a lot of PCB’s at the same time and was obviously in a bit of a hurry. The cost of the PCB’s is no worry, but it takes 6 weeks to get them. I obviously need to double check this before ordering PCB’s, but as I have said before – I always expect 2-3 rounds with corrections.