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IMX6UL doubts on ecspi w/o pull-up / pull-down

Question asked by joseph Stewart on Jun 9, 2017
Latest reply on Jun 11, 2017 by igorpadykov

I'm using the IMX6UL in a new board we've built. This board uses ecspi1-4.


On ecspi1 and ecspi2, I have pull-ups on CS and pull-downs on CLK and MOSI and have no problem talking to the devices connected there.


On ecspi3 and ecspi4, I do not have pull-ups or pull-downs and talk to a different type of devices (the reason why is b/c I didn't review the schematic and catch this until very recently).


Anyway, I cannot talk to my SPI device on on ecspi3 or ecspi4. I believe this is due to the lack of pull-up/down, but I'm not sure. I will bread-board this change ASAP, but wanted to ask here if the pull-up/down resistors are necessary, or if there's a GPIO/SPI controller setting on the IMX6UL that can accomodate this.


Thanks in advance for any suggestions.