MSPM0G3507: Exception occurs when PWM duty cycle is set to 0

Torris Yin

Part Number: MSPM0G3507
Other Parts Discussed in Thread: SYSCONFIG

Tool/software:

Hi, I noticed a problem when I used Sysconfig to configure the PWM module.

We have to configure "PWM Period Count", which determines the PWM frequency. Also, the "Counter Compare Value" of each channel is related to PWM channel duty. The Sysconfig tool can help us calculate the "Counter Compare Value" if we change the "Desired Duty Cycle (%)". If I set "Desired Duty Cycle (%)" to 0, Sysconfig will set "Counter Compare Value" to the same value as "PWM Period Count". However, the value set to the TIMx.LOAD register is "PWM Period Count" - 1, but the value of TIMx.CC is "Counter Compare Value". As a result, TIMx.LOAD is smaller than TIMx.CC, and this will result in a duty of 100% even if we set the duty to 0%.

24 days ago

0 Torris Yin 24 days ago

Prodigy 30 points

+1 Janz Bai 23 days ago in reply to Torris Yin

TI__Expert 4040 points

Hello Torris,

Because the timer will count from "Load" value to "0" value, so the actual completed counting cycle is the "PWM Period count" + 1. For getting the accurate PWM frequency, Sysconfig will use the "PWM Period count" -1 into LOAD register, so we recommend that if you want to generate the PWM whose duty cycle is 0, the max value of the CC is "PWM Period count" -1.

Best Regards,

Janz Bai

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MSPM0G3507: Exception occurs when PWM duty cycle is set to 0