HD64F2145 Datasheet, PDF (471/829 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

The reception procedure and operations using the HNDS function, by which the data reception
process is provided in 1-byte units with SCL fixed low at each data reception, are described below.
1. Clear the TRS bit in ICCR to 0 to switch from transmit mode to receive mode.
Clear the ACKB bit in ICSR to 0 (acknowledge data setting).
Set the HNDS bit in ICXR to 1.
Clear the IRIC flag to 0 to determine the end of reception.
Go to step [6] to halt reception operation if the first frame is the last receive data.
2. When ICDR is read (dummy data read), reception is started, the receive clock is output in
synchronization with the internal clock, and data is received. (Data from the SDA pin is
sequentially transferred to ICDRS in synchronization with the rise of the receive clock pulses.)
3. The master device drives SDA low to return the acknowledge data at the 9th receive clock
pulse. The receive data is transferred from ICDRS to ICDRR at the rise of the 9th clock pulse,
setting the ICDRF, IRIC, and IRTR flags to 1. If the IEIC bit has been set to 1, an interrupt
request is sent to the CPU.
The master device drives SCL low from the fall of the 9th receive clock pulse to the ICDR data
reading.
4. Clear the IRIC flag to clear the wait state.
Go to step [6] to halt reception operation if the next frame is the last receive data.
5. Read ICDR receive data. This clears the ICDRF flag to 0. The master device outputs the
receive clock continuously to receive the next data.
Data can be received continuously by repeating steps [3] to [5].
6. Set the ACKB bit to 1 so as to return the acknowledge data for the last reception.
7. Read ICDR receive data. This clears the ICDRF flag to 0. The master device outputs the
receive clock to receive data.
8. When one frame of data has been received, the ICDRF, IRIC, and IRTR flags are set to 1 at the
rise of the 9th receive clock pulse.
9. Clear the IRIC flag to 0.
10. Read ICDR receive data after setting the TRS bit. This clears the ICDRF flag to 0.
11. Clear the BBSY bit and SCP bit to 0 in ICCR. This changes SDA from low to high when SCL
is high, and generates the stop condition.
Rev. 2.0, 08/02, page 431 of 788