R01UH0092EJ0110 Rev.1.10
Page 561 of 807
Jul 31, 2012
M16C/64C Group
25. Multi-master I
2
C-bus Interface
25.3.2
Generating a Start Condition
Follow the procedure below when the ES0 bit in the S1D0 register is 1 (I
2
C interface enabled) and the
BB bit in the S10 register is set to 0 (bus free). Figure 25.6 shows the Procedure to Generate a Start
Condition.
(1) Write E0h to the S10 register.
The I
2
C interface enters the start condition standby state and the SDAMM pin is released.
(2) Write a slave address to the S00 register.
A start condition is generated. Then, the bit counter becomes 000b, the SCL clock signal is output
for 1 byte, and the slave address is transmitted.
After a stop condition is generated and the BB bit becomes 0 (bus free), a write to the S10 register is
disabled for 1.5 fVIIC cycles. Therefore, even if the S00 register is subsequently written to, a start
condition is not generated. When generating a start condition shortly after changing the BB bit from 1 to
0, confirm that both bits TRX and MST are 1 after executing step (1), then execute step (2).
Figure 25.6
Procedure to Generate a Start Condition
Yes (Bus free)
BB bit in the S10 register = 0?
Interrupt disabled
Set E0h to the S10 register
Set slave address to the S00 register
Interrupt enabled
No (Bus busy)
Bus status checked
Start condition standby
Start condition trigger generated
Start condition generated
Completed
Summary of Contents for M16C Series
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