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PWM (Pulse Width Modulation) in DM8168 platforn

Muhammad Salih
Expert 2725 points

HI,

I am using the latest EZSDK, 5_05_02_00 for DM8168 board. I want to know whether the PWM support is available in this SDK. If so, what is the procedure to enable PWM and test it.

Thanks in advance.

Regards,

Salih

  • 0
    TI__Guru**** 170625 points

    Salih,

    From the hardware side, DM816x supports PWM on the 32-bit GP Timers (4 to 7) output pins/signals. See DM816x datasheet and TRM:

    9.19 Timers
    Dedicated input trigger for capture mode and dedicated output trigger or pulse width modulation (PWM) signal

    4.2.16 Timer Signals

    TIM4_OUT - PINCTRL203 - Timer4 capture event input or PWM output

    TIM5_OUT - PINCTRL204 - Timer5 capture event input or PWM output

    TIM6_OUT - PINCTRL205 - Timer6 capture event input or PWM output

    TIM7_OUT - PINCTRL206 - Timer7 capture event input or PWM output

    chapter 21 Timers

    From the software side, we do not have support for Timer4 to Timer7 in linux kernel:

    http://processors.wiki.ti.com/index.php/TI81XX_PSP_04.04.00.01_Release_Notes#What.27s_Supported

    http://processors.wiki.ti.com/index.php/TI81XX_PSP_04.04.00.01_Feature_Performance_Guide#TI81XX

    See also the below e2e threads:

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/214722.aspx

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/227956.aspx

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/717/t/131529.aspx

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/128795.aspx

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/168671.aspx

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/717/t/254719.aspx

    Regards,
    Pavel

  • 0 in reply to Marvin Woo
    Expert 2725 points

    Hi,

    Is there any driver is available to test this PWM?. I want to adjust my LCD brightness in the sysfs entry using command line. Should I need to write any separate driver for the same?. I am not seeing any pwm device driver added in the platform side?. What are the things needs to be done to make it work?..

    Thanks in advance,

    Regards,

    Salih

  • 0 in reply to Muhammad Salih
    Intellectual 560 points

    Hi Salih,

    There is NO pwm driver available in your SDK. You have to insert the pwm module in your linux kernel by yourself. 

    #insmod dm8168_pwm.ko

    dm8168_pwm.c and Makefile are available at  http://blog.csdn.net/wu20093346/article/details/30247597

    you will get dm8168_pwm.ko if you put dm8168_pwm.c and Makefile in the same folder and #make.