TMS320 F28335 16 PWM Signals needed

Bhanu Angirekula

Other Parts Discussed in Thread: CONTROLSUITE

Hello All,

I know that I can generate a maximum of 12 PWM signals using ePWM predefined function. Can I generate a PWM signals using other pins. If so how can I do it? I would be grateful If someone posts the code with reply.

Thank you

Manideep

over 14 years ago

0 Brett Larimore over 14 years ago

TI__Guru 57255 points

Manideep,

The F28335 can output up to 18 PWM outputs.

There are 6 PWM modules on the F28335. Each module allows two PWM outputs. So, the PWM modules can generate 12 PWM outputs total.

Each of the 6 eCAP modules on the F28335 can also be configured to output a PWM waveform. To figure out how to generate a PWM with the eCAP peripheral, I would recommend looking at the following example in controlSUITE:
C:\TI\controlSUITE\device_support\f2833x\v132\DSP2833x_examples_ccsv4\ecap_apwm\

Thank you,
Brett

0 Bhanu Angirekula over 14 years ago in reply to Brett Larimore

Prodigy 200 points

Thank You So much Brett Larimore.That was so kind of you.

0 Brett Larimore over 14 years ago in reply to Brett Larimore

TI__Guru 57255 points

I edited the above post. There are 6 eCAP modules on the F28335.

Thanks,
Brett

0 Bhanu Angirekula over 14 years ago in reply to Brett Larimore

Prodigy 200 points

Hey Brett Larimore,

I couldn't find any example in the link you gave me.Can you please check once again.

0 Brett Larimore over 14 years ago in reply to Bhanu Angirekula

TI__Guru 57255 points

Manideep,

You'll need to download controlSUITE to have access to these examples:
http://www.ti.com/controlsuite

Thank you,
Brett

0 Rosmadi Abdullah over 12 years ago in reply to Brett Larimore

Prodigy 60 points

Hi,

If I need 24 pwm output? how can I do it using F28335?

0 Brett Larimore over 12 years ago in reply to Rosmadi Abdullah

TI__Guru 57255 points

Hi Rosmadi,

As described above, the F28335 can generate 12 PWMs from its six ePWM modules and 6 from the eCAP modules for a total of 18.

To generate more than 18 PWMs on the F28335, you'll need to generate the extra PWMs via software. (perhaps toggling GPIOs that are configured as outputs. Because they would be generated like this, these PWMs would not be able to run at high speed because it would eat into your available CPU bandwidth for control/communication stacks/etc.

The F28M36x series of C2000 Concerto MCUs has twelve ePWM modules and can therefore generate 24 PWM outputs directly. This may be of interest to you if bandwidth is a concern.

Thank you,
Brett

0 Rosmadi Abdullah over 12 years ago in reply to Brett Larimore

Prodigy 60 points

Thank you Brett for your response..

I have done the first method proposed by you by toggling the GPIO and you are correct. Pwm generated using GPIO suffer delay. I'm trying to reduce the coding hopefully it will help. If not successful in two weeks I need to buy the F28M36X..

Thank you,

Rosmadi

0 Brett Larimore over 12 years ago in reply to Rosmadi Abdullah

TI__Guru 57255 points

Rosmadi,

The following link may be useful:
http://processors.wiki.ti.com/index.php/General_Purpose_IO_%28GPIO%29_FAQ_for_C2000#Q:_How_can_I_toggle_a_GPIO_pin_as_fast_as_possible_in_C.3F

Thank you,
Brett

0 Shambhu Sau over 11 years ago in reply to Brett Larimore

Prodigy 200 points

Hi Brett,
6 eCAP module can be used as PWM module, however in eCAP module only count up option is available. Is there any way to get count up and down mode such that the carrier signal would be symmetrical?

I need total 18 independent PWM signals which should be generated by comparing phase shifted symmetrical triangular carrier waveform with sinusoidal reference waveform. I can use TMDSDOCK28346 docking station with TMDSCNCD28346 control card. But there is nothing about ADC in pinout mapping in the file ~controlSUITE\Development Tools\ControlCards\controlCard Hardware files\Delfino C2834x DIM168 controlCard\C28345-168 Control Card Pinout [R11].pdf , though I belief the ADCs are there.

I can use also TMDXDOCK28377D docking station with TMDXCNCD28377D control card. However ~controlSUITE\Development Tools\ControlCards\controlCard Hardware files\Delfino C2834x DIM168 controlCard\TMDSCNCD28377D_180cCARD_pinout_R1_1.pdf only gives mapping for 8 PWM modules.

Thanks
Shambhu

0 Brett Larimore over 11 years ago in reply to Shambhu Sau

TI__Guru 57255 points

Hi,

The C28346 chip does not have an on-chip ADC.

The eCAP module can only do asymmetric PWM waveforms (count-up mode in ePWM speak).

Thank you,
Brett

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TMS320 F28335 16 PWM Signals needed