I have a adafruit Ulitimate GPS Breakout attached to my rpi4B. It has a rtc built in that reads from the GPS satellites. I have gpsd installed on my rpi to run the GPS and the gpsd daemon automatically sets the rpi clock to gps time and adjusts it to local time according to the raspi-config settings for locality. I didn't have to do any special configuration to my rpi to get it to read correct gps/rtc time on OAP.
However, I can't use the hwclock utilities. I get the error message:
"hwclock: Cannot access the Hardware Clock via any known method."
Using hwclock -r --verbose, it indicates "no usable clock interface found."
I suppose that's because I did not configure one of the three rtc choices available as indicated above. Still, I get the right time displayed on OAP.
However, I can't use the hwclock utilities. I get the error message:
"hwclock: Cannot access the Hardware Clock via any known method."
Using hwclock -r --verbose, it indicates "no usable clock interface found."
I suppose that's because I did not configure one of the three rtc choices available as indicated above. Still, I get the right time displayed on OAP.