
M37221EF-XXXSP,M37221EFSP
MITSUBISHI MICROCOMPUTERS
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER
with ON-SCREEN DISPLAY CONTROLLER
25
(7) STOP Condition Generating Method
When the ES0 bit of the I2C control register (address 00DA16) is “1,”
execute a write instruction to the I2C status register (address 00D916)
for setting the MST bit and the TRX bit to “1” and the BB bit to “0”.
Then a STOP condition occurs. The STOP condition generating tim-
ing and the BB flag reset timing are different in the standard clock
mode and the high-speed clock mode. Refer to Figure 22, the STOP
condition generating timing diagram, and Table 4, the START condi-
tion/STOP condition generating timing table.
Table 4. START condition/STOP condition generating timing table
Item
Setup time
Hold time
Set/reset time
for BB flag
Standard clock mode
5.0
s (20 cycles)
5.0
s (20 cycles)
3.0
s (12 cycles)
High-speed clock mode
2.5
s (10 cycles)
2.5
s (10 cycles)
1.5
s (6 cycles)
Note: Absolute time at
φ = 4 MHz. The value in parentheses de-
notes the number of
φ cycles.
Fig. 21. START condition generating timing diagram
Fig. 22. STOP condition generating timing diagram
Fig. 20. Interrupt request signal generating timing
Fig. 19. Structure of I2C status register
7
MST
0
I2C status register
(S1 : address 00D916)
Last receive bit (Note)
0 : Last bit = “0”
1 : Last bit = “1”
General call detecting flag
(Note)
0 : No general call detected
1 : General call detected
Slave address comparison
flag (Note)
0 : Address disagreement
1 : Address agreement
Arbitration lost detecting flag
(Note)
0 : Not detected
1 : Detected
I2C-BUS interface interrupt
request bit
0 : Interrupt request issued
1 : No interrupt request
issued
Bus busy flag
0 : Bus free
1 : Bus busy
Communication mode
specification bits
00 : Slave receive mode
01 : Slave transmit mode
10 : Master receive mode
11 : Master transmit mode
TRX BB PIN AL AAS AD0 LRB
Note: These bit and flags can be read out but cannot
be written.
SCL
PIN
IICIRQ
I2C status register
write signal
Reset time for
BB flag
Hold time
Setup
time
SCL
SDA
BB flag
I2C status register
write signal
Set time for
BB flag
Hold time
Setup
time
SCL
SDA
BB flag
Setup
time
(6) START Condition Generating Method
When the ES0 bit of the I2C control register (address 00DA16) is “1,”
execute a write instruction to the I2C status register (address 00D916)
for setting the MST, TRX and BB bits to “1.” Then a START condition
occurs. After that, the bit counter becomes “0002” and an SCL for 1
byte is output. The START condition generating timing and BB bit set
timing are different in the standard clock mode and the high-speed
clock mode. Refer to Figure 21, the START condition generating tim-
ing diagram, and Table 4, the START condition/STOP condition gen-
erating timing table.