The board has an external OpAmp U3 as stuffing option. However, during testing with the external OpAmp, we realized that the microcontroller pins influence the OpAmp operation even if they are in high impedance state.
Solution: Cut the the three traces to the internal OpAmp (see following picture) with a knife if the external one should be used.
The board has an external OpAmp U3 as stuffing option. However, during testing with the external OpAmp, we realized that the microcontroller pins influence the OpAmp operation even if they are in high impedance state.
Solution: Cut the the three traces to the internal OpAmp (see following picture) with a knife if the external one should be used.