topic Controlling WS2812B LED Strip From IMX6SL over PWM in i.MX Processors

Controlling WS2812B LED Strip From IMX6SL over PWM

sandeepajesh — Tue, 13 Sep 2016 07:08:05 GMT

Hi NXP,

We want to control WS2812B Led Strip from IMX6SL SOC over PWM . I am planning to use the EPDC_SDCE2/I2C3_SCL/PWM1OUT line of iMX6 to do this job. We have also made the necessary changes to the DTS file to use this pin as PWM. Linux driver currently being loaded is pwm-imx.

To drive this LED strip we need to send 24-Bit patterns at 800kHz with a delay of 50us for each LED on the strip.

My queries below:-

1) Can you please let us know that imx6sl pwm output would be able to drive this LED strip?

2) Can you please let us know which user mode driver in kernel is responsible for controlling brightness of the LED's over pwm. Had this tried before?

3) Is Hardware DMA mandate to drive this LED strip?

4) Can you please Let us know the clock configuration to drive this LED over pwm?

References:-

1) LED:- https://acrobotic.com/datasheets/WS2812B.pdf

Regards

Sandeep S

Re: Controlling WS2812B LED Strip From IMX6SL over PWM

igorpadykov — Tue, 13 Sep 2016 10:20:03 GMT

Hi Sandeep

I am not aware of use cases with that LED strip, seems one can try

pwm-backlight i.MX6SL EVK driver

linux-2.6-imx.git - Freescale i.MX Linux Tree

please refer to description in Chapter 47 Pulse-Width Modulator (PWM) Driver

attached Linux Manual.

Best regards
igor
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Re: Controlling WS2812B LED Strip From IMX6SL over PWM

sandeepajesh — Thu, 15 Sep 2016 12:15:03 GMT

Hi Igor

Thanks for the reference.

We need to generate 800Khz on PWM2 out. Can you please help us in configuring this. I mean PWM register configuration.

Regards

Sandeep S