ADC issue STM32H723ZG with IHM08M1

[evanpol]

Hi all,

I'm in the process of configuring my STM32H723ZG to work with the IHM08M1 motor driver shield.

Currently I am trying to configure and validate the signals from the ADCs however I am having some issues with this. One ADC I'm trying to validate is the DC voltage bus reading. This circuit simply places the input through a voltage divider with some protection, going straight to the ADC after. I've tried configuring these ADCs in a few different ways, single channel, DMA, etc. however none of them produce the expected results. 

What I'm currently seeing is that with the stm and shield disconnected, I can read the correct stepped down voltage on the shield side by probing with a multimeter (~0.5V depending on input voltage). When the stm is disconnected to the shield the ADC reads a floating ~1.64 volts. With the two connected the ADC seems to still be reading 'garbage' values, probing with a multimeter reads ~1.75 volts. The last bit of information I have is that by grabbing on to the ADC pin directly I am able to drive the signal to either 0V with ground or 3V3 with the stm's voltage source, and successfully read this in code.

I am relatively new to STM's so i appreciate you taking the time and effort to help me, any and all feedback is welcome.

Thanks

[AScha.3]

Hi,

just ...maybe helping, if you would reveal which connections you talk about:

[evanpol]

Hi AScha.3, 

Thank you for your reply. I am seeking help with all ADCs, the specifc one I am referring to is for voltage bus measurements, configured on pin PA1. It is located in the top middle portion of the image you sent me. Attached is the assisting circuitry for the input.

Thank you for your help.

Schematic diagram

[AScha.3]

Hi,

how did you connect to the H7 board ? (because its for morpho connector on nucleo64 boards fitted.)

[evanpol]

Hi,
I soldered two sets of header pins to the nucleo board to connect the
shield, ensuring that the pins specified in the motor drivers datasheet
lined up with those on the stm. This meant that the side with the buttons
on the nucleo was covered.

[AScha.3]

Ok,

so assuming you did it correct:

...seems, your "A1" is then PC0 on the H7 /144 board. Try this as the analog Vin.

see in circuit...and check on which pins you come out on this board !

https://www.st.com/resource/en/schematic_pack/mb1364-h723zg-e01_schematic.pdf