We would like to use an STM32G4 to (sinusoidally) control 6 high-current BLDC motors, each with 3 digital Hall effect sensors, and each using 3x PWM Mode for control (in addition to monitoring the voltage across 1 or 3 shunt resistors on each motor for current sensing - we plan to use a DRV8323S driver and 3 CSD88584Q5DC dual MOSFETs for each motor). The G4 reference manual (RM0440) section 27.3.29, Interfacing with Hall sensors, suggests the use of an “interfacing timer�? to read the 3 Hall sensors, and an additional advanced-control timer (triggered by the interfacing timer) to generate 3 PWM signals to drive each motor. Thus, 12 timers, with 3 channels each, appear to be needed to drive 6 motors using STM32G4s. We are considering 2 possible solutions for this situation:
A) We are using an STM32G474VE for a related board and are considering using the same MCU for this board if possible. In order to use a single STM32G474VE to control our 6 motors, we would need to use 6 timers [either the advanced TIM1, 8, 20, or the 4-channel general purpose TIM2, 3, 4, 5] as “interface timers�?, and then some combination of (a) one of the remaining timers from the 7 previously mentioned, (b) the other general purpose timers (TIM15, 16, 17), and (c) HRTIM1, to generate the 18 PWMs necessary to drive the 6 BLDC motors using 3x PWM Mode. The concern here is that the RM specifically suggests using the advanced-control timers (TIM1, 8, 20) to generate the output PWMs. We are wondering if there is a need to use the advanced-control timers for this purpose, or if it would be possible to use some combination of channels from various other timers, such as the following combination:
TIM1, 8, 2, 3, 4, 5 - interfacing timers (using channels 1/2/3 on each)
TIM20_CH1/2/3 - PWM outputs to motor1
TIM15_CH1/2, TIM16_CH1 - PWM outputs to motor2
HRTIM1_CHA1/2, TIM17_CH1 - PWM outputs to motor3
HRTIM1_CHB1/2, HRTIM1_CHC1 - PWM outputs to motor4
HRTIM1_CHD1/2, HRTIM1_CHF1 - PWM outputs to motor5
HRTIM1_CHE1/2, HRTIM1_CHF2 - PWM outputs to motor6
In other words, can an “interfacing timer�? trigger outputs on specific timer channels (as shown above, including timers and are not TIM1, 8, or 20), rather than using one advanced timer for each motor as the RM suggests?
B) The alternative would be to use twoSTM32G4’s with at least three advanced (TIM 1, 8, 20) and three 4-channel general purpose (TIM 2, 3, 4, 5) timers on each, following more closely the setup described in the RM to control three motors with each STM32G4.
We are pretty sure solution B would work, IAW the suggestion in the RM. Would solution A also work? Are there other options or modifications that you would recommend?
