TMP91C824
91C824-156
2008-02-20
3.10.4 I
2
C Bus Mode Control
The following registers are used to control and monitor the operation status when using
the serial bus interface (SBI) in the I
2
C bus mode.
Seirial Bus Interface Conrol Register 1
7 6 5 4 3 2 1 0
Bit symbol
BC2
BC1
BC0
ACK
SCK2
SCK1
SCK0/
SWRMON
Read/Write W
R/W
W
R/W
After
reset
0 0 0 0 0 0
0/1 (Note 3)
Function
Number of transferred bits (Note 1)
Acknowledge
mode
specification
0: Not
generate
1: Generate
Internal serial clock selection and
software reset monitor (Note 2)
Internal serial clock selection <SCK2:0> at write
000
001
010
011
100
101
110
111
n
=
5
n
=
6
n
=
7
n
=
8
n
=
9
n
=
10
n
=
11
- Note
4
- Note
4
- Note
4
- Note
4
63.5 kHz
32.0 kHz
16.1 kHz
(Reserved)
System clock: fc
Clock gear: fc/1
fc
=
33 MHz
(internal SCL output)
fscl
=
[Hz]
Software reset state monitor <SWRMON> at read
0
During software reset
1 Initial
data
Acknowledge mode specification
0
Not generate clock pulse for acknowledge signal
1
Generate clock pulse for acknowledge signal
Number of bits transferred
<ACK>
=
0
<ACK>
=
1
<BC2:0>
Number of
clock pulses
Bits
Number of
clock pulses
Bits
000
001
010
011
100
101
110
111
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
9
2
3
4
5
6
7
8
8
1
2
3
4
5
6
7
Note 1: Set the <BC2:0> to 000 before switching to a clock-synchronous 8-bit SIO mode.
Note 2: For the frequency of the SCL line clock, see 3.10.5 (3) Serial clock.
Note 3: Initial data of SCK0 is “0”, SWRMON is “1”.
Note 4: This I
2
C bus circuit does not support fast mode, it supports standard mode only. Although the I
2
C bus
circuit itself allows the setting of a baud rate over 100kbps, the compliance with the I
2
C specification is not
guraranteed in that case.
Figure 3.10.3 Registers for the I
2
C Bus Mode
SBI0CR1
(0240H)
Prohibit
read-
modify-
write
fc
2
n
+ 8