TS-7970 Push Button

From embeddedTS Manuals

The push switch is accessed by reading FPGA registers:

tshwctl --addr 31 --peek

With no press bit 2 will be set so it will return "addr31=0x4". If there is a press it will be cleared, so "addr31=0x0".

This pin is sampled in u-boot to detect if it should stop in u-boot and look for usb updates. If this interferes with your intended usage you can boot to u-boot and disable this by running:

env delete preboot;
env set bootdelay 1;
env save;

After this change u-boot will wait 1 second on every boot for the user to press ctrl+c to break into u-boot on startup.