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TMP92CM22
2007-02-16
92CM22-174
3.10.4 I
2
C Bus Mode Control Register
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.
Serial Bus Interface Control Register 1
7 6 5 4 3 2 1 0
Bit symbol BC2 BC1 BC0 ACK SCK2 SCK1
SCK0/
SWRMON
SBI0CR1
(1240H)
Read/Write W R/W W R/W
After reset 0 0 0 0 0 0 0/1 (Note 3)
Read-
modify-write
instruction is
prohibited.
Function Select number of transferred bits
(Note 1)
Acknowledge
mode
specification
0: Not
generate
1: Generate
Internal serial clock selection and
software reset monitor
(Note 2)
000 n = 5 − kHz (Note4)
001 n = 6 − kHz (Note4)
010 n = 7 − kHz (Note4) System clock: f
SYS
011 n = 8 75.8 kHz
100 n = 9 38.5 kHz
101 n = 10 19.4 kHz
110 n = 11 9.73 kHz
f
SYS
= 20 MHz (output to
SCL pin)
Frequency = [Hz]
111 (Reserved) (Reserved)
0 During software reset
1 Initial data
0 Not generate clock pulse for acknowledge signal
1 Generate clock for acknowledge signal
<ACK> = 0 <ACK> = 1
<BC2:0>
Number of
clock
pulses
Data length Number of
clock
pulses
Data length
000 8 8 9 8
001 1 1 2 1
010 2 2 3 2
011 3 3 4 3
100 4 4 5 4
101 5 5 6 5
110 6 6 7 6
111 7 7 8 7
Note 1: Set the <BC2:0> to “000” before switching to a clocked-synchronous 8-bit SIO mode.
Note 2: For the frequency of the SCL line clock, see section 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 100 kbps, the compliance with the I
2
C specification is not
guaranteed in that case.
Figure 3.10.3 Register for I
2
C Bus Mode
Internal serial clock selection <SCK2:0> at write
Software reset state monitor <SWRMON> at read
Acknowledge mode selection
Select number of bits transferred
f
SYS
2
n
+ 8