How do I synchronize the PWM signals on a c2833xx DSP?
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ePWM modules use different timers, therefore you can see a phase delay between modules. However, the ePWM blocks have synchronization capabilities, as there is a synchronization signal that goes along each PWM block.
Each ePWM block has "sync in" and "sync out" settings. ePWM1 can receive a "sync in" signal from an external pin. Its "sync out" signal can be connected to the ePWM2 "sync in", and likewise, ePWM2's "sync out" signal is connected to the ePWM3 "sync in". By doing this, you can synchronize ePWM 1, 2, and 3.
Attached is a model that demonstrates synchronization. In this model, ePWM2 and ePWM3 are synced based on ePWM1. It was arbitrarily decided that ePWM1 would send a sync signal to ePWM2 every time the counter reaches 0. ePWM2 resets its counter to 0 when receiving the sync signal and passes the sync signal to ePWM3 that resets its counter to 0 as well. This method is very robust as there is a guarantee that the timers will not shift along the way since they are resynchronized at every period of ePWM1.
More Answers (2)
Vivek on 21 Dec 2013
I have a couple of confusions. I would glad to get answer Related to synchronizing 1) I saw that Sync output of ePWM1 was selected to be CTR=0 ePWM2 was selected to be EPWMxSYNCI or SWFSNYC ePWM3 was selected to be disabled I see no sign that ePWM1 was synced to some external input and ePWM1 input is connected to ePWM1 sync output and ePWM2 sync input is connected to ePWM2 sync output. Am I missing something? Can you explain me further.
Pouriya Boostani on 31 Jul 2017
In ePWM syncing the ePWM1 is the master and the other ePWMs are the slaves. If you want to synchronize all the ePWMs you must set the ePWM1 and the other ePWMs must be set on EPWMxSYNCI.
For more information see the figure 7,8,9,49,51,53,55,59 and 61 of sprug04a.pdf.
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