Other Parts Discussed in Thread: TCA9555
I am trying to establish communication with PCA9555 io-expander chip via I2C, I am receiving NAK and my controller stops communication as expected. I even changed the chip with assumption the chip might be bad but still no luck. The PCA9555 address is set to A0:A1:A2 = 0 which corresponds to 0x20 address according to the datasheet.
One can see the controller is initiating a communication by sending 0x20 (0b0100 0000) and WriteBit set to 0 and the chip is replying NAK as the night bit. Here is the scope signals.
I tried different addresses as well. I have 10k pullups on both lines and the communication is at 100kHz.
I have already checked my code with e2e on another forum and according to TI employee on the forum, my code has no issue. Here is the link to the thread.
Here is the snapshot of the scope. The first burst is a Write attempt to select the chip internal address 0x00 and the second is a Read attempt.
Any help will be appreciated.