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M16C/5L Group, M16C/56 Group
22.3.10.2 Master Transmission
Master transmission is described in this section. The initial settings described in 22.3.10.1 "Initial
Settings" are assumed to be completed. Figure 21.17 shows master transmission operation.
The following programs (A) to (C) are executed at (A) to (C) in Figure 22.17, respectively.
SCLMM
SDAMM
IR bit in the IICIC
register
Figure 22.17 Example of Master Transmission
(A) Slave address transmission
(1) The BB bit in the S10 register must be 0 (bus free).
(2) Write E0h to the S10 register. (start condition standby)
(3) Write a slave address to the upper 7 bits and set the least significant bit (LSB) to 0. (start
condition generated, then slave address transmitted)
(B) Data transmission
2
(in I
C-bus interrupt routine)
(1) Write transmit data to the S00 register. (data transmission)
(C) Completion of Master transmission
2
(in I
C-bus interrupt routine)
(1) Write C0h to the S10 register. (Stop condition standby state)
(2) Write dummy data to the S00 register. (stop condition generated)
When transmission is completed or ACK is not returned from a slave device (NACK returned), master
transmission should be completed as shown in the example above.
R01UH0127EJ0110 Rev.1.10
Sep 01, 2011
S: Start condition
P: Stop condition
m
Slave address
S
W
(7 bits)
(A) Slave address transmission
A: ACK
R: Read
A: NACK
W: Write
s
m
s
Data
A
A
(8 bits)
Set to 0 by interrupt request acceptance or by program
(B) Data transmission
2
22. Multi-master I
C-bus Interface
m: Master outputs to SDA
s: Slave outputs to SDA
m
s
m
Data
A/A
P
(8 bits)
(C) Completion of master
transmission
Stop condition
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