I've got a custom board using SAMC21 and am comparing results across boards.
On different copies of the same exact design, I see a variation in the AtoD readings as I go from board to board.
I'm using an external reference (2.048V reference zener), which appears to be right on the money.
On some boards, the SAMC21 measures within a few millivolts.
On other boards, I'm seeing ~15mV error: with 2.048 VRef, 12 bits, that's 15 LSB counts off as I see it.
Is this normal? I'm struggling to understand the accuracy specs in the datasheet...
PS: I'm using standard ASF3 code, which appears to me to load the factory calibration values during initialization.