From 3ce6ddcdb2a7d55f117a188ced77bc5e2f1d425b Mon Sep 17 00:00:00 2001 From: Benjamin Valentin Date: Mon, 11 Nov 2019 18:07:09 +0100 Subject: [PATCH] cpu/atmega_common: cpuid: add a word of warning The CPU ID only differs in byte 4 (RC calibration) between devices. Add a word of warning to the documentation that this may not be very unique. --- cpu/atmega_common/periph/cpuid.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/cpu/atmega_common/periph/cpuid.c b/cpu/atmega_common/periph/cpuid.c index 9ae3673a8a..c892967b04 100644 --- a/cpu/atmega_common/periph/cpuid.c +++ b/cpu/atmega_common/periph/cpuid.c @@ -21,6 +21,10 @@ #include #include "avr/boot.h" +/* + * This uses the RC calibration byte as CPU ID, so it may not be very unique. + * The first three bytes are constant across different MCUs of the same series. + */ void cpuid_get(void *id) { uint8_t *out = id;