STM32F303 OPAMP Timer controlled Multiplexer mode

[Mateusz Kaskow]

I'd like to amplify two signals connected to non-inverting input of OPAMP and control which one is currently amplified by TIM1, Channel 6. This technique is described in RM0316 document, chapter 18.3.6 Timer controlled Multiplexer mode.

I've set TIM1, Channel6 to PWM Generation No Output in CubeMX, its period is 10ms, duty is 50%.

So I supposed that periodically: for 5ms VINP will be amplified, then for 5ms VINP_SEC will be amplified. But although VINP amplification looks OK, VINP_SEC is not working, it is 0 instead of 2V, like in this screenshot:

Is there any working example of OPAMP Timer controlled Multiplexer mode?

OPAMP is in PGA mode. Is Timer controlled Multiplexer mode applicable in this case?

[T J]

VINP_SEC ?

what is this signal ?

Vinn maybe ?

Vinn it is supposed to be a VRef-

so it should be ground, amplified to ground, of course...

looks like its ignoring your Vipsec pin...

indicating that you did not configure the Differential mode

or the grouping of PA6 and PB0 is not correct...

Just throwing ideas for you...

[Mateusz Kaskow]

Thanks for answer,

there is an error in the picture above: OPAMP2_VINP is at PA7, not PA6 (i'll correct it, but now have some problems with community site, it loads very long and barely works).

I think my configuration is OK, adding picture doesn't work, that's why i'm writing OPAMP configuration:

OPAMP2

Mode PGA Connected

Timer Controlled Mux Mode

Switching on Non Inverting Inputs Using Different Pins