I'm not familiar with the TCA9548, but don't you have to give the address of the register you're reading from? I know on the MCP23017 you do something like this: // Specify register to read cmd = i2c_cmd_link_create(); i2c_master_start(cmd); i2c_master_write_byte (cmd, (addr<<1) | I2C_MASTER_WRITE, ...

Didn't you say there had to be a 5 msec delay before reading the data back from the sensor? I don't see a delay in the code you posted.

Best regards,
Pete C.

Neil, I worked on your Adafruit port a bit, and got it working pretty well. I wound up writing a generic I2C register read/write library and then changed your changes to use that instead. I wired a 23017's chips two ports together, added some LEDs, and wrote a test program which alternates between t...

Hmm... I think I should have typed

Doesn't this do the same thing?