p2125vps20 Renesas Electronics Corporation., p2125vps20 Datasheet - Page 436

• Manufacturer Part Number: p2125vps20
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 16 I
The transmission procedure and operation, by which data is sequentially transmitted in
synchronization with ICDR (ICDRT) write operations, are described below.
1. Initialize the IIC as described in section 16.4.2, Initialization.
2. Read the BBSY flag in ICCR to confirm that the bus is free.
3. Set bits MST and TRS to 1 in ICCR to select master transmit mode.
4. Write 1 to BBSY and 0 to SCP in ICCR. This changes SDA from high to low when SCL is
5. Then the IRIC and IRTR flags are set to 1. If the IEIC bit in ICCR has been set to 1, an
6. Write the data (slave address + R/W) to ICDR.
7. When one frame of data has been transmitted, the IRIC flag is set to 1 at the rise of the 9th
8. Read the ACKB bit in ICSR to confirm that ACKB is cleared to 0. When the slave device has
9. Write the transmit data to ICDR.
10. When one frame of data has been transmitted, the IRIC flag is set to 1 at the rise of the 9th
11. Read the ACKB bit in ICSR.
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high, and generates the start condition.
interrupt request is sent to the CPU.
With the I
data following the start condition indicates the 7-bit slave address and transmit/receive
direction (R/W).
To determine the end of the transfer, the IRIC flag is cleared to 0. After writing to ICDR, clear
IRIC continuously so no other interrupt handling routine is executed. If the time for
transmission of one frame of data has passed before the IRIC clearing, the end of transmission
cannot be determined. The master device sequentially sends the transmission clock and the
data written to ICDR. The selected slave device (i.e. the slave device with the matching slave
address) drives SDA low at the 9th transmit clock pulse and returns an acknowledge signal.
transmit clock pulse. After one frame has been transmitted, SCL is automatically fixed low in
synchronization with the internal clock until the next transmit data is written.
not acknowledged (ACKB bit is 1), operate step [12] to end transmission, and retry the
transmit operation.
As indicating the end of the transfer, the IRIC flag is cleared to 0. Perform the ICDR write and
the IRIC flag clearing sequentially, just as in step [6]. Transmission of the next frame is
performed in synchronization with the internal clock.
transmit clock pulse. After one frame has been transmitted, SCL is automatically fixed low in
synchronization with the internal clock until the next transmit data is written.
Confirm that the slave device has been acknowledged (ACKB bit is 0). When there is still data
to be transmitted, go to step [9] to continue the next transmission operation. When the slave
device has not acknowledged (ACKB bit is set to 1), operate step [12] to end transmission.
2
C Bus Interface (IIC)
2
C bus format (when the FS bit in SAR or the FSX bit in SARX is 0), the first frame