spi Oleds(2) transfert errors with 60cm wires !


I use TX2 SPI + 2 GPIO pins to send image to both RGB oled screens.
My connections are as follow :

  • Spidev3.0 :

  • GPIO :
    GPIO298 as DC
    GPIO 388 as Reset

  • Power :
    TX2 Ground
    TX2 5v

  • frequency :

All wires are 60cm : the last 10 cm are Y form.

Both Oled screens are used as robot color eyes, and they share same wires.

When using 20cm Y wires (Card of experiment wires), both oleds screens are perfect !

When using 60cm (thin servo wires) they don’t work !

(If i only connect 1 eye, it works. But not when Both screens are connected at same time)

What could be the cause ?

Thanks a lot.

Are they twisted pair and shielded? If not, then at least try twisted pair…preferably with an outer shield.

Note that in twisted pair where more than one pair is used in a single cable (such as ethernet cable) you will find the twist pitch different between the pairs…twisted pairs running parallel to each other and using the same twist pitch will be more or less straight wires so far as the two pairs are concerned. Try ethernet cable.

Hey, Thanks for quick reply. You was right !!!

With ethernet wires, and a maximum cutting, I’m able to contact my 2 oleds at a rate of 8Mhz !

Very good !! Thanks again.