In an attempt to reduce power for a critical battery powered system, I tried, without success, to make the chip run in the power range 3 (1.2V). Here is what I do:
At power up, with the chip running from the MSI clock divided by 2 (1Mhz), whatever I write to the 2 VOS bits in the PWR_CR register, I always read back 0X1000 (range 2). Resetting power with the PWRRST bit before, or after setting VOS, doesn't help. What am I missing?
