AM2634: Synchronize two EPWM with different frequency

Hello Oleg,

1. Please use EPWM_CLKSYNC register to start the clock(Time Base clock TBCLK) of multiple EPWM instances simultaneously.

Address is 0x502F 0010 which can be obtained from CSL_CONTROLSS_CTRL_U_BASE + CSL_CONTROLSS_CTRL_EPWM_CLKSYNC

Please refer to SOC_setEpwmTbClk API for programming this register. 

\mcu_plus_sdk\source\drivers\soc\am263x\soc.c (Note that SOC_setEpwmTbClk API starts the clock of EPWM instances one by one, not multiple instances simultaneously)

For example:

If PWM1 freq required is a=25KHz (40us period) and PWM2 freq required is 100KHz (10us period)

then program PWMs as follows,

• Make  EPWM_CLKSYNC as 0. This disables TBCLK for all EPWMs
• Make TBCTL[CTRMODE]= 3 in PWM1 and PWM2. This freezes the TBCTR (time base counters)
• Write TBCTR=0 in PWM1 and PWM2. This initializes counters to 0
• Configure PWM parameters, specifically the period as follows:
  • TBPRD for PWM1 is 7999 ((7999+1)*5ns=40us).
  • TBPRD for PWM2 is 1999 ((1999+1)*5ns=10us).
• Make TBCTL[CTRMODE]= 0 or 1 or 2 (depending on your use case) in PWM1 and PWM2. This starts the TBCTR (time base counters), and waits till clocks are enabled
• Write EPWM_CLKSYNC with bit mask to enable required PWMs (2 bits in your use case).  This enables TBCLK for the chosen EPWMs

Observe the PWMs

Please note that this is a one time synchronization of PWMs

2. Please use same steps above, but configure the initial TBCTR value as 40000 (40000*5ns = 200000ns) for a delay of 200us in one PWM

If the period (PWM frequency) is constant for the use case (no frequency modulation is required), then use above method of one-time synchronization of PWMs. If frequency modulation is required, the use EPWMxSYNCI, EPWMxSYNCO and TBPHS (sync in, sync out and phase shift) feature of EPWM.

Thanks

K.Sanjeev