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TCA6408A: The reg value is changed not as expected

Part Number: TCA6408A

hi all,

I have used tca6408 in my carrier board with the driver kernel-4.9/drivers/gpio/gpio-pca953x.c.

I use the GPIO Sysfs Interface in userspace and I find a strange phenomenon that I echo gpio-num of P0 to export it,

and echo 'out' to  set P0 direction, then other pins' direction are all changed which is not expected!

By the way,  the exported gpionum is p0(the base number) , is there any relationship with it? 


  • Hi Yun,

    Can you get scopeshots of SDA/SCL when you write to the device and verify the data you are writing matches with the expected write? (Post scope shot on here for us to double check)

    Do you have a schematic we can review?