In a certain SMT production, it was found that the STM32 ADC testing was inaccurate upon return for testing.
The MCU produced in Malaysia seems to be fine, as such a large manufacturer would not likely produce counterfeit MCUs.
So, I started to look for the cause myself. I tested the power supply, voltage reference, crystal oscillator, and the sampling rate of the generated ADC project, but found no improvement.
I searched online for many possible reasons and even consulted AI, but there didn’t seem to be a clear cause.
Later, by verifying the internal reference voltage of the chip through the program, I discovered that the abnormal reference voltage was full scale = 4096, which is not the normal value we usually see; it should be around 1.2 volts to be considered normal.
