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How to synchronize EVA timer1 and EVB timer3 in TMS320F2812 ?

Nguyen Hieu
Prodigy 20 points 


Hello !
I am using TMS320F2812 in my Z-source inverter project. I need generate 6 independent PWM pulses
 using both EVA and EVB ( using EVA timer1 with 3 compare registers in EVA  and EVB timer3 with 3 compare
 registers in EVB ).
PWM pulses generated by 2 EV have the same period, but the start point of PWM pulses generated by EVA don't
 meet the start point of PWM pulses generated by EVB in each period. 
How can I solve this problem ? How to synchronize 2 EV ?
Thanks !

  • 0
    Genius 5885 points

    Hi Nguyen

    I used to do it like this:

    1. have both timers in stop mode

    2. increase T3CNT value so that is a couple integers biger than T1CNT (it takes a little experimentation to figure out the correct value)

    3. start T1

    4 start T3

    You might want to write an assembly routine doing this as you'd have more precise control over instruction timing

     

    Off topic if you are using ezDsp kit I'd recommend you to switch to 2808 or even 28335 as they have much more flexible PWM unit which is more suitable for Z-source topologies and pinout is more or less the same making the migration fairly easy

    Regards, Mitja

  • 0 in reply to Mitja Nemec
    Prodigy 20 points

    thank you very much ! 

    You reminded step 3 and 4. we must start  T1, T2 at the end of the initialization subprogram .