527
Table 16.8
I
2
C Bus Timing (with Maximum Influence of t
Sr
/t
Sf
)
Time Indication (at Maximum Transfer Rate) [ns]
Item
t
Indication
t
/t
Influence
(Max.)
I
2
C Bus
Specification
(Min.)
=
5 MHz
=
8 MHz
=
10 MHz
t
SCLHO
0.5t
SCLO
(–t
Sr
)
Standard mode
–1000
4000
4000
4000
4000
High-speed mode –300
600
950
950
950
t
SCLLO
0.5t
SCLO
(–t
Sf
)
Standard mode
–250
4700
4750
4750
4750
High-speed mode –250
1300
1000
*
1
1000
*
1
1000
*
1
t
BUFO
0.5t
SCLO
–
1t
cyc
( –t
Sr
)
Standard mode
–1000
4700
3800
*
1
3875
*
1
3900
*
1
High-speed mode –300
1300
750
*
1
825
*
1
850
*
1
t
STAHO
0.5t
SCLO
–
1t
cyc
(–t
Sf
)
Standard mode
–250
4000
4550
4625
4650
High-speed mode –250
600
800
875
900
t
STASO
1t
SCLO
(–t
Sr
)
Standard mode
–1000
4700
9000
9000
9000
High-speed mode –300
600
2200
2200
2200
t
STOSO
0.5t
SCLO
+
2t
cyc
(–t
Sr
)
Standard mode
–1000
4000
4400
4250
4200
High-speed mode –300
600
1350
1200
1150
t
SDASO
(master)
1t
SCLLO
*
3
–
3t
cyc
(–t
Sr
)
Standard mode
–1000
250
3100
3325
3400
High-speed mode –300
100
400
625
700
t
SDASO
(slave)
1t
SCLL
*
3
–
12t
cyc
*
2
(–t
Sr
)
Standard mode
–1000
250
1300
2200
2500
High-speed mode –300
100
–1400
*
1
–500
*
1
–200
*
1
t
SDAHO
3t
cyc
Standard mode
0
0
600
375
300
High-speed mode 0
0
600
375
300
Notes: The maximum operating frequency for the H8S/2169 and H8S/2149 is 10 MHz.
1. Does not meet the I
2
C bus interface specification. Remedial action such as the following
is necessary: (a) secure a start/stop condition issuance interval; (b) adjust the rise and
fall times by means of a pull-up resistor and capacitive load; (c) reduce the transfer rate;
(d) select slave devices whose input timing permits this output timing.
The values in the above table will vary depending on the settings of the IICX bit and bits
CKS0 to CKS2. Depending on the frequency it may not be possible to achieve the
maximum transfer rate; therefore, whether or not the I
2
C bus interface specifications are
met must be determined in accordance with the actual setting conditions.
2. Value when the IICX bit is set to 1. When the IICX bit is cleared to 0, the value is (t
SCLL
–
6t
cyc
).
3. Calculated using the I
2
C bus specification values (standard mode: 4700 ns min.; high-
speed mode: 1300 ns min.).