Jinx wrote:
> No takers for my question ? - What is the purpose of a NACK ?
>
> Is it a terminating  /ACK in a data stream with an indeterminate
> number of bytes ? Which needs to be detected by the status of
> the ACKSTAT and ACKDT bits ?

I'm not sure what your question is, but the ACK bit is sent by the receiver
after receiving each byte.  It lets the transmitter know that someone was
out there and received the byte.  A IIC transfer can not continue after a
NACK.  A deliberate NACK can used to indicate the end of variable length
transfers.  The ACK or NACK response to the address byte is also used by the
master to determine whether there is any slave out there responding to that
address.

Beware of the MSSP bug where the master can see NACK even when a slave sent
ACK.


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