nRF51 and nRF52 ADC calibration information

[Masahiro Kondo]

Hello. I have read a topic about ADC calibration (gain and offset error in 0x10000024) of nRF51822 here but I can't find the document describing it. Could anyone point me where the description of this register is (is it part of FICR?)? And also, does nRF52832 have the same register that I can use to adjust gain and offset inside firmware?

Thank you for the help.

[Stefan Birnir Sverrisson]

Hi Masahiro

The calibration values at address 0x10000024 only apply to nRF51 third revision chips. For nRF52, there are no calibration values that I know of. You need instead to periodically calibrate the SAADC by calling the TASKS_CALIBRATEOFFSET task.

[Masahiro Kondo]

I am not sure if I understood you correctly. Do you mean +-2% "after" calibration method applied? I guess +-2% is "before" calibration otherwise it doesn't make sense that Rev2 chips which don't have calibration coefficients also has +-2% as ADC error. It sounds like it will be much better for 25C (my application is pretty close to 25C) after calibration done but you don't have any spec like it will be +-0.5% or something like that? Thank you for your help.