DC bias on STM32L using internal OP-AMP and DAC

[djd53]

Hi there,

I have a signal which is in the range +600mV. I want to read this using the internal ADC on the STM32L475 uC. To do so, I know I have to shift the signal so it is fully above 0V and I want to do this by connecting the internal DAC to the non-inverting input of one of the internal opamps and then the output of said opamp to the ADC. According to this document, section 3.4.3,  it's possible to do with the STM32G series but can it be done with the STM32L series? 

Additionally, if I had more signals (say 3 for example), do the opamps have a multiplexed input to allow this as there are only 2 opamps present. Again, according to that document, the STM32G series has this but I can't see anything about the STM32L series.

Thank you in advance for any help!!

[TDK]

Inputs on the OPAMP are limited to 0 to VDDA. If you want to shift a signal with a range below that, you'll need an external op-amp.

You could use a resistor divider to shift it into the 0-VDDA range and input to an ADC, if your signal can handle a small resistive load. Could also AC couple it, if you're not interested in DC content.