Is it possible to use the internal OPAMP from the STM32G4 series with only the VINPx pin assigned to a physical pin? Configured as non-inverting, negative feedback with a gain.

MWält.2 · ‎2021-08-16

I would like to implement a current sensing using a grounded shunt resistor. Therefore I would like to use the build-in OPAMP from the STM32G491 Series. But I'm not satisfied with the CubeMX configuration.

In AN5306 I found a configuration under 4.4.1. But within CubeMX I'm not able to configure the OPAMP using only one pin.

I would like to use the VINPx pin, connect the output intern to the ADC and use the feedback loop internally with a gain of 64.

Further, is it possible to use VINPx as input with the output connected internally and externally with a "static" configuration?

Again, not using the VINMx pin.

Igor Cesko · ‎2021-08-19

Hi MWält.2 ,

You are right - this combination is missing in CubeMX (I will report it to include this useful configuration). This OPAMP config is possible to set.

For your today setting: In CubeMX select OPAMP mode "Follower Internally connected" and then in code change the mode from follower to PGA. So - thios must be done manually now. We will try to improve this.

Your second configuration: The OPAMP uses as output external pin and on the same pin is also ADC input. This feature is possible to perform also in CubeMX - select more functions on the same pin - manually (like on PA2: OPAMP1_VOUT and ADC1_IN3).

Regards

Igor

MWält.2 · ‎2021-08-30

Hi Igor Cesko,

Thanks for your reply. I'm gonna try it manually for now and looking forward to the CubeMX integration.

Regards

Matthias

Igor Cesko · ‎2021-09-02

Hi MWält.2 ,

There was put request to change / improve this OPAMP modes selection in CubeMX. So - in next CubeMX versions this should be corrected.

Regards

Igor