TMS320F28P550SJ: CLBXBAR Output not working

Hi Dennis,

Can you provide us with the .syscfg file used her for XBAR configuration?

I don't see anything specifically wrong with your expected configuration details.

Can you confirm the EPWM[1:3][A:B] signals are acting as expected before being fed to the CLB?

Have you properly configured the GPIO Pinmux to enable the correct XBAR output mux mode?

Best Regards,

Zackary Fleenor

Zackary,

Attached is my .syscfg file.

Test1053.syscfg.zip

The EPWM signals for EPWM1 and EPWM2 worked fine when using the override function of the CLB. The override was not available for EPWM3 which is why I ended up using the XBAR output. I believe that I configured the GPIO Pinmux correctly but you should be able to check the SysConfig file.

Is there problems with the SysConfig? I have another ticket where I can't add a DCL Controller using SysConfig when I have CLA modules.

Thanks

Dennis

Hi Dennis,

Thank you for sharing this file. I am reviewing it now.

Can you confirm the exact expected outcome for the EPWM3 signal flow you want to implement from your original thread? A block diagram of some sort may help clarify.

Best Regards,

Zackary Fleenor

Zackary,

The CLB takes the ePWM output and converts it into a pulse train which starts with a 120uSec pulse followed by a 15kHz pulse train. 

Thanks

Dennis

Hi Dennis,

Can you provide scope shots of the valid and invalid signals for reference?

Is there any application code that you can share to show the current working implementation?

Best Regards,

Zackary Fleenor

Zackary,

Here is the output of the simulation that was done for the CLB. The three inputs are the ePWM gate signals with the FSM Output being the pulse train. 

Here is a copy of the latest test code.

3482.test1053_13.zip

Let me know if you need anything else.

Thanks

Dennis

Zackary,

Any progress on understanding the problem??

Thanks

Dennis

Hey Dennis,

Apologies for the delayed response. I've been swamped catching up after the Thanksgiving break.

Can you provide the details from the prior ticket where you were suggested to use the CLBXBAR and XBAR Output to just output the state machine?

This all seems valid, I need to loop in the CLB expert to provide additional insight into the CLB configuration.

Best Regards,

Zackary Fleenor

Zachary,

Here is the link to the previous question.

 TMS320F28P550SJ: CLB program to override EPWM 

Thanks

Dennis

Hi Dennis,

I am going through the files you shared. Thanks for sharing them. In the Sysconfig file, I can see ePWM modules 2,3,4,5,6,7 are configured. And inputs to CLB are from ePWMs 1,2,3. Please correct me if I am wrong. 
Meanwhile I will try to find if there is any problem with the configuration.

Thank you,
Praneeth

Praneeth,

The ePWM that are used by the CLB are ePWM 1, 2, and 3. The CLB is used to make a gate pules train of 120uSec first pulse with 15kHz pulse train. I looked at using the Chopper module in the ePWM but could not get the frequency down low enough. Right now, I originally was using the CLB override function which works for ePWM1 and ePWM2. I could not get it to work for ePWM3 so it was suggested to use XBar outputs to send the CLB output to the ePWM pins. That is where the output never turns on so there are no gate pulses generated. 

Hope this helps explain the problem. If we can get ePWM1 working, I'm sure the others will work also since the XBar outputs were available to go to the ePWM1, 2, and 3 pins.

Thanks

Dennis

Dennis,

Thank you for briefing me the problem you are facing. I request you to clarify one thing, in the sysconfig file you have shared, ePWM1 module is not configured. But, as you have described, ePWM1 will be used by CLB. So, is it configured later? 

Thanks
Praneeth

Praneeth,

Attached is the latest software that I am testing. It uses the CLB override rather than the XBAR output. The ePWM1 and ePWM2 are configured as SCR1_2. I would like to convert that to using the XBAR output.

test1053.zip

Thanks

Dennis

HI Dennis, 

I have configured a simple CLB tile which takes input from PWM1A and outputs to a GPIO using CLB_OUTPUTXBAR. Both the pins, PWM output pins and CLB_OUTPUTXBAR Gpio pins are giving pulses. Now, I am looking at your code and trying to find differences in the configurations, if any. I will get back to you in a day or two.

Thanks
Praneeth

Praneeth,

The latest code that I sent you does not have the XBAR output but just the CLB override. I tried to add an XBAR output instead of the CLB override to test PWM1A but get a resource conflict when I try to assign the XBAR to GPIO00.

Please explain the correct way to add the XBAR.

Thanks

Dennis

Praneeth,

That allowed me to use the CLB XBAR output to connect to the pins. It did cause another problem. ePWM is synced to the zero crossover of the AC line using XBAR INput5. When I use the CLB for the output rather than the override, I loose my sync. The sync is done by generating a zero cross using the PPB of the ADC that monitors the AC line. A GPIO pin is turned on and off to confirm the zero cross is working. That GPIO pin is connected to XBAR Input5 which is used to sync ePWM1.

Is there another way to sync ePWM to eliminate the problem. I did generate a ePwm Trip based on the ADC Event using the ePWM XBAR but could not get it to sync the ePWM.

Thanks

Dennis

Hi Dennis,

As we are using crossbars instead of override, delay is possible. In other words, it is not the fastest way to do this. Unfortunately, apart from using overrides or through XBARs, I do not think any other way is feasible.

Thanks
Praneeth

Praneeth,

Initially, I could use overrides on ePWM1A/B using CLB1 and ePWM2A/B using CLB2 but could not use overrides on ePWM3A/B. Is there a way to do an override on ePWM3A using CLB1 and ePWM3B using CLB2?

Thanks

Dennis

Dennis,

Unfortunately, override function is available only for ePWM1 and ePWM2 modules in this device. It is not available for ePWM3 module. 

Thanks
Praneeth

Praneeth,

The CLB generates the correct gate pulse train when using the CLB override function. I need to sync the signal to the ADC zero crossing which I have done both by using INPUT XBAR5  or EPWMXBAR Trip 10. I can use the CLB XBAR output to generate the gate pulse train in order to eliminate having to use the CLB override. The gate pulse train is correct but the ePWM sync is lost when I use the CLB XBAR output. I have tested both the INPUT XBAR5 and EPWMXBAR Trip 10 methods but neither works. The CLB output is the state output which is (s0 & boundary input 0) where boundary input 0 is the ePWM signal. Shouldn't the ePWM boundary input be synced to the zero cross and therefore the s0 output would also be synced? If I can get the sync to work with the CLB XBAR output, I am not limited by the ePWM1 and ePWM2 overrides.

Thanks

Dennis

Dennis,

There will be some delay from input to the state output of CLB, adding to the delay due to CLBXBAR. These delays could be the reason for syncing issues you are facing. Overriding will eliminate the significant XBAR delays. 

Thanks 
Praneeth

Praneeth,

I understand that there will be some delays but I think they will be so small not to cause a problem. The delays I’m seeing can be in milliseconds. The sync is to a power line and the CLB output basically slides compared to the power line.

Thanks

Dennis

Dennis,

Milliseconds of delay is something I have not heard before. Let me check internally if anyone has faced this kind of delay.

Thanks
Praneeth

Dennis,

Can you please share the details like how you measured delay? A scope shot would be very helpful. 

Thanks 
Praneeth

Dennis

That is great! I am closing the thread now.

Thanks
Praneeth