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TCA9555: Status not correct as real I/O level while configured as INPUT

Benjamin Zhou
Expert 4000 points

Part Number: TCA9555

Hi Team,

  My customer used TCA9555 as I2C I/O expander, they reported an issue that:

   --The IO0_0 configured as INPUT,  which connect with 3.3V pull up resister and the key pad,   while the Key is pressed down, the IO0_0 is turn to low level, after hours run, the IO0_0 was always to low level but actually there is no Key pressed down.  

   --Reset the MCU, the IO0_0 is still in low level state;

   --Reset the I2C, the IO0_0 is still in low level state; 

   --The other 4 IO configured as Input exist the same issue;   the other IO configured as output worked as normal.

   --Powered off the system, and powered on the system,  the issue can't be reproduced. 

Support Need:

  Which steps are correct to initialize the TCA9555 and which should be pay attention for the IO configuration?  Which command can be used to reset the TCA9555?

  Expect for your reply, thanks.

Best Regards

Benjamin

  • 0
    TI__Guru* 78531 points

    Hey Benjamin,

    Are you able to post a schematic of the TCA9555? (If not online we can do it via Email)

    "   --Powered off the system, and powered on the system,  the issue can't be reproduced. "

    - How many times have you seen this issue happen? Is it just one device doing this?

    "  Which steps are correct to initialize the TCA9555 and which should be pay attention for the IO configuration? Which command can be used to reset the TCA9555?"

    -Doing a power cycle should work to reset our device. The device should be set as an input after the power cycle. One thing you can do if you see this issue again is to read the registers of the device and check to see if the configuration registers have changed. (Maybe it is possible that the mcu configured the device to be an output low sometime while you let the device sit for hours)

    Thanks,

    -Bobby