Philips CEM2100/00, Service Manual

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Page 195
T
5CL8
16. Serial Bus Interface(I
2
C Bus) Ver.-D (SBI)
The T
5CL8
has a serial bus interface which employs an I
2
C bus.
The serial interface is connected to an external devices through SDA and SCL.
The serial bus interface pins are also used as the port. When used as serial bus interface pins, set the output latches
of these pins to "1". When not used as serial bus interface pins, the port is used as a normal I/O port.
Note 1: The serial bus interface can be used only in NORMAL1/2 and IDLE1/2 mode. It can not be used in IDLE0,
SLOW1/2 and SLEEP0/1/2 mode.
Note 2: The serial bus interface can be used only in the Standard mode of I
2
C. The fast mode and the high-speed mode
can not be used.
Note 3: Please refer to the I/O port section about the detail of setting port.
16.1 Configuration
Figure 16-1 Serial Bus Interface (SBI)
16.2 Control
The following registers are used for control the serial bus interface and monitor the operation status.
• Serial bus interface control register A (SBICRA)
• Serial bus interface control register B (SBICRB)
• Serial bus interface data buffer register (SBIDBR)
• I
2
C bus address register (I2CAR)
• Serial bus interface status register A (SBISRA)
• Serial bus interface status register B (SBISRB)
16.3 Software Reset
A serial bus interface circuit has a software reset function, when a serial bus interface circuit is locked by an exter-
nal noise, etc.
To reset the serial bus interface circuit, write “10”, “01” into the SWRST (Bit1, 0 in SBICRB).
And a status of software reset canbe read from SWRMON (Bit0 in SBISRA).
Noise
canceller
Noise
canceller
SCL
Input/
output
control
SDA
SBI control register B/
SBI status register B
SBI control register A/
SBI status register A
I 2 C bus
address register
SBI data
buffer register
Shift
register
I
2
C bus data
control
Transfer
control
circuit
I
2
C bus
clock sysn.
Control
Divider
fc/4
SBICRB/
SBISRB
I2CAR SBIDBR
SBICRA/
SBISRA
SCL
SDA
INTSBI interrupt request