How are VDDA, AGND and VREFP connected to the MCU-Pins on NucleoH723ZG?

[DFehr.1]

Hello everyone,

I am using the NucleoH723ZG board and I'd like to use the internal reference voltage for ADC-purposes. Initialising the VREFBUF...

VREFBUF->CSR &= ~VREFBUF_CSR_VRS_Msk; //Voltage Reference set to 2.5V

VREFBUF->CSR &= ~VREFBUF_CSR_HIZ_Msk; //VREF+ pin is internally connected to the voltage reference buffer output

VREFBUF->CSR |= VREFBUF_CSR_ENVR; //Enable Voltage Reference

while(!((VREFBUF->CSR) & VREFBUF_CSR_VRR)) //Wait for voltage reference ready

{

;

}

...the code gets stuck in the while-loop. (The clock is also enabled for VREF) Is it possible that this is not intended using the Nucleo Board? I wonder how the VREFP signal on the Nucleo board is connected to the Microcontroller (respectively to the VDD?). Unfortunately I couldn't found the answer in the user manual of the nucleo board.

Thank you for your help.

Dietmar

[TDK · Accepted solution]

Schematics for all boards are available as well.

https://www.st.com/en/evaluation-tools/nucleo-h723zg.html#cad-resources

 

Connecting 2.5V to 3.3V clearly isn't going to work.

[DFehr.1]

Thank you TDK! I didn't know the schematics are available online...

Removing R36 should be enough, am I right? Would it cause any trouble?

[TDK]

Seems like it would work. Looks like there are already external caps on that line as well, which are required.