ADC and DAC issue-Hardware

[Amal1]

I’m using an STM32F439VIT6 on a custom board. PA5 is used as the DAC output, and PA0/PA1 as the ADC inputs. On 1 out of 5 boards, the ADC and DAC functions stopped working, but the same pins still work correctly as GPIO.

Setup (failing board)

PA5: DAC → op-amp → 0–10 V output

PA0, PA1: ADC inputs from INA190A1 for 4–20 mA sensors

VDDA/VREF+ = 3.3 V (measured OK)

Same firmware as working boards

Pins configured in analog mode

Issue

DAC produces no valid analog output, always zero

ADC readings are invalid or stuck

GPIO input/output on the same pins works

Question

Can the STM32F4 analog (ADC/DAC) circuitry be damaged while the GPIO still works on the same pins?

How can I confirm if the ADC/DAC core is damaged (e.g., internal channels/tests)

[Andrew Neil]

Welcome to the forum.

Please see: How to write your question to maximize your chances to find a solution

In particular, as it's a custom board, please post the schematic.

[TDK]

> On 1 out of 5 boards, the ADC and DAC functions stopped working, but the same pins still work correctly as GPIO.

What did you do when it stopped working? It sounds like the board has been damaged.

> Can the STM32F4 analog (ADC/DAC) circuitry be damaged while the GPIO still works on the same pins?

Sure. If the chip is damaged, the behavior is generally undefined. It is not uncommon for one function to fail but for others to work if the board has been subjected to damage.

> How can I confirm if the ADC/DAC core is damaged (e.g., internal channels/tests)

There's no 100% test here. But using the same code as on other boards to verify internal temperature and VREFINT channels would be a good start. If those are not working correctly, and the hardware is otherwise correct (e.g. no solder bridges or cold/missing connections) then the board is damaged.

[MasterT]

https://community.st.com/t5/others-stm32-mcus-related/adc-measurement-issue/m-p/879896#M9458