Hello ST Team and Community,
I’m working with the X-NUCLEO-IHM07M1 board for 6-step sensorless BLDC control, and I need some clarification regarding the purpose and correct use of the GPIO_BEMF pin.
In this ST Community answer, it is mentioned:
"The GPIO_BEMF pin is provided to manage the BEMF sampling during the PWM ON state for 6-Step control only."
I understand that this refers to enabling the BEMF voltage divider (e.g., 10k/2.2k) to bring phase voltage into the ADC range during PWM ON time. However, on the X-NUCLEO-IHM07M1, it seems that even during the PWM OFF time, if GPIO_BEMF is not pulled LOW, the voltage divider is disconnected (floating bottom resistor), and the BEMFx signal becomes unreliable or unusable for ADC reading.
So my question is:
Do we also need to pull GPIO_BEMF LOW when sampling BEMF during the PWM OFF-state (e.g., mid-off-time) in order to enable the voltage divider and get a proper ADC reading?
If not, how is the ADC expected to receive a reliable voltage at BEMFx without a complete divider path?
Thanks in advance for your clarification!
Best regards,
Duc Le
