13.3.3 Master Receive Operation
In master receive mode, the master device outputs the receive clock, receives data, and returns an
acknowledge signal. The slave device transmits the data. The receive procedure and operations in
master receive mode are described below. See also figure 13.7.
1. Clear TRS to 0 in ICCR to switch from transmit mode to receive mode.
2. Read ICDR to start receiving. When ICDR is read, a receive clock is output in synchronization
with the internal clock, and data is received. At the ninth clock pulse the master device drives
SDA low to acknowledge the data.
3. When one byte of data has been received, IRIC is set to 1 in ICSR at the rise of the ninth
receive clock pulse. If IEIC is set to 1 in ICCR, a CPU interrupt is requested. After one frame
has been transferred, SCL is automatically brought to the low level in synchronization with the
internal clock and held low.
4. Software clears IRIC to 0 in ICSR.
5. When ICDR is read, receiving of the next data starts in synchronization with the internal clock.
Steps 3 to 5 can be repeated to receive data continuously. To stop receiving, set TRS to 1, read
ICDR, then write write 0 in BBSY and 0 in SCP in ICSR. This generates a stop condition by
causing a low-to-high transition of SDA while SCL is high. If it is not necessary to acknowledge
each byte of data, set ACKB to 1 in ICSR before receiving starts.
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HITACHI [ HITACHI SEMICONDUCTOR ]
