can i share one On-Chip Crystal Oscillator for two piccolos

Pradeep,

Are you asking if you can clock the second Piccolo device with the internal oscillator of the first Piccolo device?  This is not possible that I'm aware of because our output buffers can only handle up to 15-20 MHz on this device.  After the PLL, I assume your system is running at 60 MHz.  You can not output the clock prior to going through the PLL.

However, our PWM does have many schemes built in to synchronize with external devices.  I recommend reading the ePWM user's guide found at:

http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=spruge9e&fileType=pdf

Synchronization schemes begin at pg 26.

Kris

thanks for reply,

i read that pdf and i got a idea is it good or bad i don't know but if share the crystal  for both piccolo so my both piccolo will start at same time so by this also i can achieve Synchronization and  my require is to use 3 ewpms (1a,1b,2a,2b,3a,3b) from each piccolo up to 4 piccolo or more so that i can generate up to 36 ewpms with same Synchronization.

more over i m working on concerto also but i m not clear with concerto like code exceed so right now i m working on piccolo and my device is running at 80Mhz

If you had an external crystal this may be possible, but I would be concerned about the load on the line.  If this were the case I would have to speak to some others before saying this would or would not work.  However, I can say you will certainly not want to use an internal oscillator for this scheme.

Spend some time reading the guide I linked to.  The sync schemes provided by the ePWM are very flexible.  I'm confident you can find one to work for your application.

thanks for reply, 

yaap i will........

waiting for reply hope to be +ve news...

thanks and regards,

pradeep  

Internal oscillators from two difference devices cannot be sync'd.

I do not think it would be wise to drive two difference devices with a single external crystal.  The oscillation of the crystal is caused by feedback from the X1/X2 circuitry.  I'm not sure how well it would work to have these two circuits in parallel.

You might be able to sync two devices by driving them with a single external canned oscillator, however you may still have jitter between the device SYSCLOCKs due to the PLL.

If you want to sync PWM modules between devices, your best option is probably to use the EPWMSYNCx signals.

It is not enough to just use the same crystal or oscillator.

You may be able take care of your situation by using

EPWMxSYNCI  and EPWMxSYNCO  -  these are detailed in the SPRUGE9 document: TMS320x2802x, 2803x Piccolo Enhanced Pulse Width Modulator (ePWM) Module  Reference Guide.

See section 2.2 - Time-Base (TB) Submodule

I am not sure if there exists example code to do what you want, but I remember from the 28x workshops that PWM modules could be synchronized.

Hopefully this helps,