Data Sheet

ISM14585-L35 Specification
DOC-DS-14585-201807-3.0
Confidential Inventek Systems
Page 38
that this is the last byte. The slave-transmitter relinquishes the SDA line after detecting
the No Acknowledge (NACK) so that the master can issue a STOP condition.
When a master does not want to relinquish the bus with a STOP condition, the master
can issue a RESTART condition. This is identical to a START condition except it occurs
after the ACK pulse. The master can then communicate with the same slave or a
different slave.
Figure 16 Master-Receiver Protocol
START BYTE Transfer Protocol
The START BYTE transfer protocol is set up for systems that do not have an on-board
dedicated I2C hardware module. When the I2C Controller is addressed as a slave, it
always samples the I2C bus at the highest speed supported so that it never requires a
START BYTE transfer. However, when I2C Controller is a master, it supports the
generation of START BYTE transfers at the beginning of every transfer in case a slave
device requires it. This protocol consists of seven zeros being transmitted followed by a
1, as illustrated in Figure 17. This allows the processor that is polling the bus to under-
sample the address phase until 0 is detected. Once the microcontroller detects a 0, it
switches from the under sampling rate to the correct rate of the master.