Hello,
I am working on a design involving several STM32 (STM32F100 and STM32F103). The STM32F100 are in small package so Vref and VVda are internally connected. I have checked VDDA with active probe/short gnd, the ripple is extremely low.
I wrote a fairly simple test software in order to check ADC in our design. The test is :
1. read Vrefint before calibration
2. perform calibration and display calibration data
3. read vrefint after calibration
The results are somewhat disturbing to us (the software displays raw data read in the ADC register) :
0x000002AE
Cal data
0x000003A8
0x000006EC
=> 0x2AE is 0.55V and 0x6EC is 1.43V (Vrefint is between 1.16V and 1.24V and my board is running at 20°C).
I also wonder about the high offset of the calibration data. Dis you ever encounter such offset ?
Thanks for your feedback.
