I am using the
pps-gpio dtoverlay. My
/boot/config.txt has these lines:
# Expect the GPS 1PPS pin to be connected to GPIO3 dtoverlay=pps-gpio,gpiopin=3
Problem is, that the GPS Module (SkyTraq Venus) goes into a debug mode if the PPS pin is pulled high while power is applied. According to this page, GPIO3 is pulled high by default during boot. I confirmed this on my RPI3.
When I connect PPS to GPIO18, which is pulled low during boot, it works just fine. However, I'm stuck with GPIO3, since my circuit boards are already manufactured.
sudo gpio -g mode 3 down has no effect. Is there another way to disable the internal pull-up, or even enable a pull-down, while keeping the