This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCA9554 Issue

Other Parts Discussed in Thread: TCA9554

Hi,

Customer report below issue of TCA9554. Please help comment. Thanks!

1:Register 0x01,0x03 default value be read out is 0x00,not 0xff

2:Write value 0xff to register 0x01,But the data be read out is 0x4a(not 0xff) and the IO status also is 0x4a

3:I2C clock is 100Khz,Device addr is 0x20!

regards

david

  • Hello David,

    A common issue I find when debugging these issues is that often times there is another I2C slave on the bus that happens to have the same i2C address.

    The reason why I also think this is because all the values you would expect to get are masked by 0's, which are the dominate bit in I2C. for example, if 2 devices ever try to communicate, and 1 transmits a 1, the other transmits a 0, a 0 will be what is seen on the bus every time.

    I would review your schematic in detail and double check the I2C address of every slave device on the bus.

    Or try changing the address of the TCA9554 and see if this problem goes away.