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OPAMP2 -> ADC, no signal

Question asked by kledtke.steve.002 on Oct 9, 2015
Latest reply on Oct 12, 2015 by kledtke.steve.002
Hey there,

using a STM32L476 board, I configured opamps1 and 2 chained, using opamp1 in conjunction with DAC to Change the DC Offset, and opamp2 in PGA mode. The Input signal gets passed through, we measure it on the output pin of OPAMP2 with oscilloscope, it Looks as expected.

But I don't get a Signal on the ADC - which as such is configured correctly (clocks etc), as when I configure an Input pin as ADC control and Input a Signal, it is sampled corectly.

I use ADC1 Channel 15, which goes on PB0, and from what I understand of the manual, should be connected to opamp2.out when configured as ANALOG.
But all I "receive" is noise of ~ -56dB, although the signal level at the opamp output pin looks good.

Is there more to do?
What exactly is necessary to connect the output of OPAMP2 to an ADC channel to sample the signal?
Are there constraints, e.g. if some hardware blocks are used in a certain mode, the opamp + ADC does not work, or something like that?

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