Controlling WS2812 device on Omega2 board
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Re: Controlling WS2812 device (RGB LED strip)
I have ported the above mentioned ws2812 driver in to latest SDK running kernel 4.14.
Driver source: https://github.com/jnweiger/ws2812_sprites/tree/master/carambola2/package/ws2812_draiveris/src
I haven't modified anything in the driver except #include <asm/uaccess.h> to #inlclude <linux/uaccess.h> as the asm/uaccess.h was throwing error of incompatibility.After compiling it successfully for omega2, i am able to insert it successfully via insmod, the dmesg shows appropriate logs as well.
But when I try to write to glow LEDs(echo "}!!!}!!!}" > /dev/ws2812) it does not show any effect on the specified GPIO pin.I am using GPIO 18 and my LED has 5 leds in it; I am following below sequence,
insmod ws2812_driveris.ko gpios=18 leds_per_gpio=5
echo "}!!!}!!!}" > /dev/ws2812This does not have any effect on LEDs, LEDs are in Off state.
I am suspecting that the low level GPIO registers which are being written/read in the driver are not for Omega2.
Help me to understand this better!Thanks in advance.
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However I am able to access the GPIO 18 with sysfs interface, to make it hgh-low.
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Hi @dixit,
the
ws2812_draiverisdriver is for the AR9331 SoC. This was used in the first Omega(1), that's what we've had at the time, and that's what I portedws2812_draiverisfor back in 2016.Today's Omega2 family however are all based on MediaTek's MT7688 SoC, which is quite different hardware. So you ws2812_draiveris will never work on a Omega2.
But no worries - a much better solution than
ws2812_draiverisexists since 2017 for the Omega2, and has in fact become part of the official firmware -p44-ledchain. It uses MT7688 PWM to generate the WS281x data without blocking IRQs. See this thread for the history how it came into existence.The p44-ledchain README explains how to use it, and there are also a few other threads in this forum with some Q&A about WS281x and
p44-ledchain.happy LED hacking
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@luz I got it from there only, Thanks.
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p44-lechain is amaaaaazing! Makes using LEDs really easy. Thank you @luz
