Can FreeRTOS software timer generate PWM?

[HMSEdinburge]

Hello, i am using F446 and i am contemplating using FreeRTOS CMSIS V2 software timer to generate PWM to control motors via motor drivers (IC  chipset). Is this possible? Or must I use the hardware timer, TIM1~7 ?

[mƎALLEm]

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@HMSEdinburge wrote:

These are the motors i m using, BLDC, stepper, servo actuators, stepper motor need 1/32 steps, BLDC needs PWM, and their various motor drivers, gate drivers etc. Total 63 motors. 

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Already said that's not possible.

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• Software PWM is limited in frequency/resolution. If you want 0-100 steps and use a 1 ms tick your frequency will be 10 Hz. 
• You can share timers and handle things in software. But this results in dither as interrupt latency is not always predictable. Also can be a high load to CPU
• Best is to use hardware timer
• second best is to use external PWM IC. For example a SPI or I2C PWM IC. Such as the 16 channel PCA9685. Note that the PCA9685 is optimized for LEDs, but you can can connect it to a transistor switching a DC motor. Or to the enable pin of an H-bridge and use software to switch direction.

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@HMSEdinburge wrote:

These are the motors i m using, BLDC, stepper, servo actuators, stepper motor need 1/32 steps, BLDC needs PWM, and their various motor drivers, gate drivers etc. Total 63 motors.

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• BLDC needs 3 phase control synchronized with back-emf detection. An MCU is not powerful enough to do several of these. Get a dedicated motor control IC/complete motor driver for each BLDC motor.
• Get a dedicated motor control IC/complete motor driver for each stepper motor.
• If they are RC servos you can use the PCA9685 for the 1-2ms pulse

63 motors seems like a lot. If the MCU has to do additional processing it may be underpowered. It's also rather ambitious for a beginner such as yourself. What is the application?