Low-side current sensing – correct ADC trigger timing on IHM07M1?

[Esakkimuthu]

Hi everyone,

I am using the IHM07M1 inverter board to run a PMSM motor, and I need to measure the phase current using the low-side shunt resistor. Currently, I configured the ADC in injected mode and trigger it from a timer event on the falling edge of the PWM.

I have a few doubts:

1. Is triggering the ADC on the PWM falling edge the correct method for accurate low-side current sampling?

2. Since current flows through the low-side shunt only when the low-side MOSFET is ON, should I trigger the ADC only during the low-side ON time, or is it valid to sample at any moment in the PWM cycle?

3. I am using Timer1 with 3 channels for PWM generation, and Channel 4 (CH4) as a compare channel to trigger the injected ADC.
   What value should I assign to OCxREF4 for correct sampling timing?
   I’m confused about how to choose the right compare value inside the PWM period. 

If anyone has experience with this setup, please share your guidance. Thanks!