TMS320F28375S: TMS320F28375S

Hi Muzammil,

Keep in mind that the frequency of your TBCLK (f_TBCLK) is a scaled version of the frequency of your EPWM clock (not your system clock which is 200MHz). The EPWM clock should be 100MHz max as defined by the device datasheet section 7.11.2.2.1 ePWM Timing Requirements. There is also a note in the datasheet there that states " For SYSCLK above 100 MHz, the EPWMCLK must be half of SYSCLK." meaning that your EPWMCLK should be 100MHz (there is a divider (EPWMCLKDIV) of the system clock that defaults to EPWMCLK = SYSCLKOUT/2).

With the CLKDIV and HSPCLKDIV dividers set to 1, the TBCLK frequency should be100MHz. So if your target PWM frequency is10kHz, you should indeed be using a TBPRD of 5000 as you have currently set for up-down count mode correctly.

Could you please double check that the clock divider bits are correctly set during debug? If one of these is set to /2 that would explain the 5kHz (HSPCLKDIV specifically is set to /2 by default).

Best Regards,

Allison

Hello Allison,

Thanks for correcting me.

F_tbclk is actually 100 MHz. even though I have set true value in TBPRD (5000). still i am not getting 10KHz frequency.

Allison Nguyen said:

Could you please double check that the clock divider bits are correctly set during debug? If one of these is set to /2 that would explain the 5kHz (HSPCLKDIV specifically is set to /2 by default).

Secondly, can you please help me with my second issue related to delay in vTaskDelay function in FreeRTOS which i have mentioned earlier?

thanks for your support.

Hello Allison,

After checking, my all peripherals are working on half the frequency from which i have set.

means they are working on 100 MHz instead of 200 MHz.

I am using Launchpad F28379D because i come to know that i can run my f28375s code in launchpad (considering the peripheral / device differences).is there any settings on launchpad that i am missing??

Hi Muzammil,

Could you check the clocktree in SysConfig so we can trace the clock source back and see what dividers/multipliers are being used for SYSCLK --> PLL --> EPWMCLK...?

• There is a new video on using the clocktree tool here: https://www.youtube.com/watch?v=SJlegD-S89o 

Regarding the Free RTOS question - I am speculating this may be resolved when we figure out the half-frequency clocking issue. If not, I will loop in a Free RTOS expert for some help with that

Best Regards,

Allison

Hello Allison,

here is the screenshot of my clock tree. Please guide me if anything is wrong in this clock source.

Allison Nguyen said:

Regarding the Free RTOS question - I am speculating this may be resolved when we figure out the half-frequency clocking issue.

Yes, I am also assuming that.

thanks and regards

Hi Muzammil,

The clocktree looks good to me so far, so I will try to test this on my end. In the meantime you can also scope out the clocks (e.g. PLL, SYSCLK, etc) by using the sysctrl module. There is not a C2000Ware example to do this for this specific device, but there is an example for another device you can reference ({C2000Ware}\driverlib\f28p65x\examples\c28x\sysctl\sysctl_ex2_xclkout_config.c) and select which clock to route out to a GPIO.

By using an oscilloscope with this, you can check that the frequencies indeed match what is expected based upon your clock multipliers/dividers.

Best Regards,

Allison

Hello Allison,

for some reason, there is not showing the reply option on your thread. i don't know why so i am reply to this.

coming to my question, i show that the clocking functions in Device.c file are not taking parameters from clocktree.h file but instead of that they are taking parameters from Device.h file. can this be the source of errors???

thanks and regsrds

Hi Muzammil,

Thanks for the note about it going to Device.h. I've been trying to test out some of our examples and I see the same behavior on this single core and the dual-core version of the device at the moment. I also did triple check that the device.h files share the same configurations for the clock settings between the 2 devices, but I want to look more into some of the clock dividers and will get back to you with an update tomorrow. 

Best Regards,

Allison

Hi Muzammil, 

Please allow for another day for me to look into this. Thanks for the patience!

Best Regards,

Allison

Hello Allison,

Not a problem

thanks for support.

Hi Muzammil,

Apologies again for some delay but I will try to find more clarity on if it's in device.h by end of Monday. I also wanted to be sure I asked if you are using our C2000Ware EPWM examples or your own code? If you haven't already, you could try out one of our examples and see if you get a similar result based on the TBPRD? Another question- if you switch count modes to asymmetric (e.g. up-count) do you still see half the expected frequency?

Best Regards,

Allison

Hello Allison,

Allison Nguyen said:

you could try out one of our examples and see if you get a similar result based on the TBPRD?

I have already checked the example (epwm_ex2_updown_aq) and other like this, and it is working fine in this case. but i think that the the EPWM module is not configured by sysconfig tool in that projects. but it is configured manually by making initEPWM1(); functions like this. so the change in Ftbclk by syscongif does not effect to epwm frequency in this case.

Allison Nguyen said:

if you switch count modes to asymmetric (e.g. up-count) do you still see half the expected frequency?

for up/down case the formula is,

but for only up-count the formula is,

so it is obvious that the frequency will change.

please correct me if i am wrong.

thanks and regards.

Hi Muzammil,

Muzammil Qureshi said:

I have already checked the example (epwm_ex2_updown_aq) and other like this, and it is working fine in this case. but i think that the the EPWM module is not configured by sysconfig tool in that projects.

Thanks for letting me know. I will look into other sysconfig based projects for this. Would you also be able to attach your code? Or if it is based on a specific sysconfig project, let me know.

As for changing the count modes, what I meant was that you could change to up-count and alter the TBPRD accordingly with that second equation (so you would use TBPRD = 10000) to see if you are able to get the desired 10kHz frequency or if you still see 5kHz. That was just a thought to be sure that it wasn't dependent on your EPWM counter settings and was a project-level issue

Best Regards,

Allison

Hello Allison,

Allison Nguyen said:

Or if it is based on a specific sysconfig project, let me know.

I have made my project form existing project "cla_ex1_asin" and modified it according to my use.

Allison Nguyen said:

That was just a thought to be sure that it wasn't dependent on your EPWM counter settings and was a project-level issue

as i have mentioned previously that, After checking, not only EPWM but all peripherals are working on half the frequency from which i have set. e.g. timers, freertos etc.

I am attaching my code here,

2577.motor-controller-ti.zip

please note that, i have included the clocktree.h file in Device.c and i have commented the necessory clock function in Device.h file so that it can take that arguments from clocktree.h file. at this stage the code is working fine but as i remove the clocktree.h file from Device.c, the clock functions take the arguments from Device.h and the issue begins. i just want to find the root cause so that this problem do not occur afterwards.

thanks and regards

Hi Muzammil,

Thanks for the info. Can you please send a screenshot of the SYSPLLMULT and SYSCLKDIVSEL register values while running? I want to check exactly what these are set to during run time.

Best Regards,

Allison

Hello Allison,

I don't know exactly what you are asking for but i have sent my whole project in previous message. can you please check it from there for me?

btw i am using launchpad F28379D for now.

thanks for your support.

the frequency problem will occur when you will remove the "CPU1_RAM/syscfg/clocktree.h" file from device.c and include device.h file.

Hello Allison,

Thank you for your continuous support, i really appreciate it.

Allison Nguyen said:

Looking at the device.h file, the project must accidentally be pulling in the F2837xS ControlCard default configurations, which uses a 20MHz OSC source and IMULT of 20. The F2837xS LaunchPad has a 10MHz OSC source and should hence be using an IMULT of 40. I believe this is what was causing the issue - so while the device.h is correct, the wrong board-specific configurations were being pulled into the project.

So all this clocking issue was because of using the Launchpad F28379D (which i am using currently but with TMS320F28375S based project). that is what you are trying to say??

Allison Nguyen said:

• When you see an ifdef symbol like “_LAUNCHXL_F28377S” AND that is the board you are using for your tests, you will need to add a pre-defined symbol to your project so that it can recognize the board you are using and implement any changes accordingly
• To add the pre-defined symbo

I have selected TMS320F28375S for my project but as i come to know that there is no any board related to this controller(please suggest if any), so i am using the Launchpad F28379D till my actual PCB of TMS320F28375S gets ready which is in R&D stage at this time. (please note that i am not using 77S but i am using 75S).so which predefined symbol should i use for that??

Allison Nguyen said:

Please note that this frequency change and difference in board-specific configurations are not a concern with newer devices and with SysConfig support.

overall, the issue was not in clock selection but in the controller selection and in the symbols. that is what you are trying to say??

thanks and regards