Philips CEM2100/00, Service Manual

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Page 206
16. Serial Bus Interface(I2C Bus) Ver.-D (SBI)
16.6 Data Transfer of I2C Bus
T
5CL8
16.6.3.1 When the MST is “1” (Master mode)
Check the TRX and determine whether the mode is a transmitter or receiver.
(1) When the TRX is “1” (Transmitter mode)
Test the LRB. When the LRB is “1”, a receiver does not request data. Implement the process to
generate a stop condition (Described later) and terminate data transfer.
When the LRB is “0”, the receiver requests next data. When the next transmitted data is other than
8 bits, set the BC, set the ACK to “1”, and write the transmitted data to the SBIDBR. After writing
the data, the PIN becomes “1”, a serial clock pulse is generated for transferring a next 1 word of data
from the SCL pin, and then the 1 word of data is transmitted. After the data is transmitted, and an
INTSBI interrupt request occurs. The PIN become “0” and the SCL pin is set to low level. If the data
to be transferred is more than one word in length, repeat the procedure from the LRB test above.
Figure 16-10 Example of when BC = “000”, ACK = “1”
(2) When the TRX is “0” (Receiver mode)
When the next transmitted data is other than of 8 bits, set the BC again. Set the ACK to “1” and
read the received data from the SBIDBR (Reading data is undefined immediately after a slave
address is sent). After the data is read, the PIN becomes “1”. A serial bus interface circuit outputs a
serial clock pulse to the SCL pin to transfer next 1-word of data and sets the SDA pin to “0” at the
acknowledge signal timing.
An INTSBI interrupt request occurs and the PIN becomes “0”. Then a serial bus interface circuit
outputs a clock pulse for 1-word of data transfer and the acknowledge signal each time that received
data is read from the SBIDBR.
Figure 16-11 Example of when BC = “000”, ACK = “1”
D7 D6
2 3 4 5 6 7 8 9
D5 D4 D3 D2 D1 D0
1
Acknowledge
signal from a
receiver
SCL pin
SDA pin
PIN
INTSBI
interrupt request
Write to SBIDBR
D7 D6
2 3 4 5 6 7 8 9
D5 D4 D3 D2 D1
New D7
D0
1
Acknowledge
signal to a
transmitter
SCL pin
SDA pin
PIN
INTSBI
interrupt request
Read SBIDBR