MSP432E401Y: Create staggered pulses using the PWM TIDriver.

Timothy Carbo

Part Number: MSP432E401Y

Hi,

I would like to setup two PWM generators on the MSP432 to generate staggered pulses - that is one channel has a time delay relative to the other. See the description/diagram below. I would really like to use the TI/Drivers API since my application is RTOS. I have tried starting the PWM1 using a timer to offset its start from the PWM2 but it is not clear from my scope if that is working. Any thoughts would be greatly appreciated.

Regards,

Tim

The desired wave form produced by two pulse width modulators is shown below. Pulse Width Modulator #1 has an output pulse repetition interval of PRI₁ and a pulse width of PW₁, while Pulse Width Modulator #2 has an output pulse repetition interval of PRI₂ and a pulse width of PW₂. PRI₁ is equal to PRI₂ as is PW₁ is equal to PW₂.

Phase delay, PD, is the offset in time between the leading edge of a PWM #1 pulse and the leading edge of a subsequent PWM #2 pulse. Our intent is to control PD in 31ns steps.

over 5 years ago

0 Timothy Carbo over 5 years ago

Intellectual 505 points

Hi, the graph didn't appear to paste so I just uploaded a document that describes what I would like to do.

Regards,

Tim

Desired_PWM_waveform.pdf

0 Chris Sterzik over 5 years ago in reply to Timothy Carbo

TI__Guru 53525 points

Hello,
In order to provide the phase shift you would need to perform this at the register level since neither the TIDrivers nor the DriverLib support this.

Please refer to this post:
e2e.ti.com/.../700714

Additional discussions and examples:
e2e.ti.com/.../740544

dev.ti.com/.../

Regards,
Chris

0 Timothy Carbo over 5 years ago in reply to Chris Sterzik

Intellectual 505 points

Chris,

I read the posts and looked at the pwm_genx_syncgenerators DirverLib example in the MSP432 SimpleLink SDK and it seems like I might be able to do what I want using that code as a guide. Am I missing something? However, my application is RTOS and all the examples are NoRTOS. Is it possible to integrate NoRTOS code into my RTOS application? Are there no options in RTOS that will allow me to do this?

Regards,

Tim

0 Timothy Carbo over 5 years ago in reply to Timothy Carbo

Intellectual 505 points

Chris,

I have reviewed all the examples and discussions you provided. Unfortunately, using NoRTOS is not an option for me at this time. Is it possible to extend the TI-Drivers PWM API to get it to do what I want? Are there examples/guidelines on how to do this?. I have the source code for the PWM API, but not sure as to the best approach for extending the library and integrating it into my application. Any advice/guidance you and your team can provide would be much appreciated.

Regards,

Tim

0 Chris Sterzik over 5 years ago in reply to Timothy Carbo

TI__Guru 53525 points

Yes. You can extend the drivers, but I am not aware of any examples of how to do so. Practically, you would pull the drivers PWMMSP432E4.c/.c into the top layer of the project and CCS will give that instance precedent over the code in the library. You will need to update the includes accordingly in your files.

I think you are aware but here is the doxygen, dev.ti.com/.../_p_w_m_m_s_p432_e4_8h.html

Regards,
Chris

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MSP432E401Y: Create staggered pulses using the PWM TIDriver.