Using an LTC4151IMS#TRPBF.
I'm attempting to read the SENSE, VIN, and ADIN registers from a microcontroller over I2C @ 100KHz and coming across a very strange problem I haven't seen with this part before.
We are leaving both ADR pins open, so I've got an address of 0xCC for writing and 0xCD for reading.
I send the Write Address (0xCC) to begin and get an ACK from the part. I then send the register I want to read and get another ACK from the part. I then send the Repeated Start (Sr) condition followed by the address with the read flag (0xCD) and get no longer get an ACK from the LTC4151. I get the same result for any of the registers I attempt to read (SENSE, VIN, ADIN).
Logic Analyzer capture of the transaction is below:
We've used this part before without any real issues, so I'm a little bit baffled on what could be going on here. The chip itself is obviously active since it responds to its (write) address, I just can't figure why it would NACK the read address? I did find another thread with a similar problem (here) but the solution doesn't seem to apply here, at least I don't think it does? I'm sending all the clocks I should be sending (although after receiving the NACK from the target, my firmware doesn't attempt to continue reading and aborts the transaction by sending a STOP. This is by design in the firmware).
As far as I can determine I am following the datasheet Fig. 7:
Any thoughts would be appreciated,
Thanks!
