M16C6K9 Datasheet, PDF (201/292 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6K9 Group
MULTI-MASTER I²C-BUS Interface
STOP Condition Generation Method
When the ES0 bit of the I²C control register is “1”, writing “1” to the MST and TRX bits, and “0” to the BB, PIN
and low-order bits of the I²C status register simultaneously enters the standby status to generate the stop
condition. The stop condition is generated after writing dummy data to the I²C data shift register. The STOP
condition generation timing is different in the standard clock mode and the high-speed clock mode. Refer to
Fig.GC-18, the STOP condition generation timing diagram, and Table GC-9, the STOP condition generation
timing table. Do not write data to I²C status register and I²C data shift register, before BB flag becomes to “0”
after the instruction to generate the stop condition to avoid the influence on generating STOP condition wave-
form.
I2C data shift register
write signal
SCL
SDA
Setup
time
Hold
time
Fig.GC-17 Start condition generation timing diagram
I2C data shift register
write signal
SCL
SDA
Setup
time
Hold
time
Fig.GC-18 Stop condition generation timing diagram
Table.GC-9 Start/Stop generation timing table
Item Start/Stop condition generation
selection bit
Setup
“0”
time
“1”
hold
“0”
time
“1”
Note: VIIC = 4MHz
Standard clock mode
5.0µs (20 cycle)
13.0µs (52 cycle)
5.0µs (20 cycle)
13.0µs (52 cycle)
High-speed clock mode
2.5µs (10 cycle)
6.5µs (26 cycle)
2.5µs (10 cycle)
6.5µs (26 cycle)
As mentioned above, Writing “1” to MST and TRX bits.
Writing “1” or “0” to BB bit, writing “0” to PIN and low-order 4 bits, simultaneously sets up the START or STOP
condition standby. It releases SDA in START condition standby, makes SDA to “L” in STOP condition
standby. The signal of writing to data shift register triggers the generation of START/STOP condition. In the
case of setting MST, and TRX to “1” but do not want to generate a START/STOP condition. Write “1” to the
low-order 4 bits simultaneously. Fig.GC-10 illustrates the function of writing to status register.
Table.GC-10 The function of writing to status register
The value of the data writing to status register
Function
MST TRX BB PIN AL AAS AS0 LRB
1 11 00 0
00
Setting up the START condition stand by in master transmission mode
1 10 00 0
00
Setting up the STOP condition stand by in master transmission mode
0/1 0/1 -
01 1
1
1
Setting up the communication mode (refer to the description on I²C status register)
Rev.1.00 Jun 06, 2003 page 201 of 290