TCA6424A not responding with ACK

The address listed in the datasheet (0x22) is often referred to as a "7-bit address", in other words drop the R/W bit and add a '0' at the front, or right shift and divide by 2.

It is possible that your software needs a 8-bit address as the input.

Read = 0x45

Write = 0x44

Since you have ADDR grounded, the "7-bit address" of 0x23 is not relevant for your application. 0x23 is equivalent to the 8-bit addresses 0x46 (Write) and 0x47 (Read).

I have tried that with no success more then that I wrote a code that send messages to all the addresses in that BUS. the TCA6424A is the only component that connected to that BUS.

There was no respond ACK to my messages.

If that's the case then I will have to see a scope shot showing SCL and SDA clearly during the communication sequence.

If you have an I²C enabled scope that would be great. If not, then I will be able to count the bits if the scope shot is clear enough.

Hi at you both,
I have the same problem with I²C. I use the Adress 0x44 (8bit), then send the command byte 0x84 (all Ports as Output) then 3 bytes 0x00 (0 Volt at each Port Pin). I get all Acknowledges, but I do not have 0 Volt at the Port Pins.
My difference in the schematic is, that VCCP is +5V and VCCI is +3,3V.
Could you help me? If I have missed something?
Best regards
Marco

Hi,
I found my solution.
I forgot to set the configuration register.