AnsweredAssumed Answered

stm32f3 ADC input conflict with opamp output?

Question asked by frackers on Nov 3, 2016
Latest reply on Jan 13, 2017 by artes.benjamin
I have a problem (I think) with PA6 in an STM32F303VCTx using it as an analog input. This pin is shared (along with other things) with opamp2_vout and even though I have not enabled any opamps, I think what I'm reading on ADC2 channel 3 is a steady level from the opamp and not my signal. It appears to operate in digital GPIO modes correctly.

The manual is very ambiguous about the opamp outputs - from the manual
"Important note: the amplifier output pin is directly connected to the output pad to minimize
the output impedance. It cannot be used as a general purpose I/O, even if the amplifier is
configured as a PGA and only connected to the ADC channel."

Is this connection present even if the opamp is not enabled (I assume the default power-up state is not enabled) or is there some specific action I have to take to use this pin other than set it as an analog input in the GPIO setup and allocate the relevant ADC channel?

Thanks

Outcomes