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F28377 100PIN PWM SYNC question

Joe Zhu
Intellectual 2540 points

Hi Champion,

F28377SPZP(100pin) package just has 15ch PWM, PWM2A, PWM2B, PWM3A, PWM6A, 6B, PWM7A, 7B, PWM8A, 8B, PWM9A, 9B, PWM10A,10B, PWM11A, 11B. PWM sync scheme in TRM as below:

my question is:

1. if I want to SYNC two independent group PWM, one need HRWPM function another is EPMW, each groupo include 3xPWM channel, as 100pin package, I can just choose PWM6-PWM8 as gproup1 for HRPWM and PWM9-PWM11 for Group2, but in the scheme, problem is PWM9 just can sync with PWM8 and cannot SYNC with PWM10 directly. So can I use PWM2 to SYNC PWM6 and PWM7, is it can be implement in 100 pin package becuause 100pin package donot have PWM1 and PWM4, so I am confuse this SYNC path is work?

2. In Revc TRM, there is a additional comment for SYNC is"make sure that the longest path does not exceed four ePWM/eCAP modules", what is means? If I use PWM1 SYN with PWM4 and PWM7 and PWM 11, ECAP1, there is 5 module SYNC, is it can implement? What's the reason to add this comment, can you give me some example maybe offend this rules?

Thanks!

BR

Joe

  • 0
    TI__Genius 10820 points

    Hi Joe,

    Please find my answers below.

    1. if I want to SYNC two independent group PWM, one need HRWPM function another is EPMW, each groupo include 3xPWM channel, as 100pin package, I can just choose PWM6-PWM8 as gproup1 for HRPWM and PWM9-PWM11 for Group2, but in the scheme, problem is PWM9 just can sync with PWM8 and cannot SYNC with PWM10 directly. So can I use PWM2 to SYNC PWM6 and PWM7, is it can be implement in 100 pin package becuause 100pin package donot have PWM1 and PWM4, so I am confuse this SYNC path is work?

    HN: Even though outputs from some of the PWM modules are not brought out to the device pins on the 100 pin package, the PWM modules may still be used as a device resource. For example PWM1 can still be the master PWM and sync PWM2 on CTR = 0. 

    2. In Revc TRM, there is a additional comment for SYNC is"make sure that the longest path does not exceed four ePWM/eCAP modules", what is means? If I use PWM1 SYN with PWM4 and PWM7 and PWM 11, ECAP1, there is 5 module SYNC, is it can implement? What's the reason to add this comment, can you give me some example maybe offend this rules?

    HN: This only limits the number of PWM modules that the source sync signal can travel through to sync a PWM module. PWM 1 sync output can be directly fed through to PWM4, PWM7, and ECAP1, so there is no issue syncing these modules to PWM1. For PWM11, the PWM1 sync signal has to go through PWM10 to PWM11. This is less than the 4 PWM module limit. So it is also possible to sync PWM11 to PWM1 at the same time while syncing PWMs 4, 7,  and ECAP1. In fact you can also sync PWM10, PWM12, PWM2, etc with PWM1 as long as the PWM1 syncout signal does not have to travel through more than 4 PWM modules.

    I hope this helps.

    Hrishi