Issues driving a ws2812b from spi on a dalhia board

[fennecdjay]

Hello.

I’m using an up to date torizon distro on a dalhia board.
My goal is to drive a ws2812b led strip from the spi.
my code works fine on a raspberry pi3.
i get inconsistent result on the dalhia.
one thing especially noticeable is that past the first use of SPI the logic analyzer starts recording right away, as MOSI is still sending some signal.
the first use is also incorrect according to the analyzer, but at least the analyzer only starts recording when the spi is asked to send something.

I’ll be happy to provide any information you need as i really want to fix this.

Have a nice day,
Jérémie

[fennecdjay]

this on the raspi, sending white

this on the raspi, sending black

this on the dalhia, first use, sending white

this on the dalhia, second use, sending white

this on the dalhia, first use, sending black

this on the dalhia, second use, sending black

[josep.tx]

Hello @fennecdjay , welcome to the community
As a first step, you can have a look at a related thread from another user:

Driving LED Strip from User space using PWM or SPI

Hello. I am trying to interface a IN-PI554FCH LED with a colibri-imx8x. In order to set the appropriate color on the LED I need to send it pulses as mentioned in the table below: [image] To achieve the required timings I am hoping to use either PWM or the SPI Bus. If I were to use the SPI bus; is the a library exposed to the user space which I can use to write the values I need on the bus or do I need to write my own custom driver in the kernel space? On raspberry Pi there is a pigpio librar…

Best regards,
Josep

[fennecdjay]

thanks a lot for the quick answer.
i’m gonna study that other thread and come back to you asap.
feel free to ask more in the mean time.

kind regards, Jérémie.

[josep.tx]

Hello @fennecdjay ,
Do you have any updates on this topic? Were you able to solve your issue?

Best regards,
Josep

[fennecdjay]

Hello.
sorry for the delay, summer is keeping me busy with making concerts so i did not have too much time too work further on that issue.
i’m collecting informations on rtos and rpmsg right now, so i should be back in a few days with a better understanding.
Thanks very much for checking in

[fennecdjay]

To keep you updated.
I managed to get decent looking spi signals from rtos.
not closing yet as i may run into configuration issues.
thanks for the help so far

[fennecdjay]

can confirm spi works fine from the M core. although for reasons i need to use a logic level translator.
closing now