TMPM330 - Keil

Under development
10.5.6 Configuring the SBI as a Transmitter or a Receiver
TMPM330 (rev 0.4) 10-15
TMPM330
Setting SBIxCR2 to “1” configures the SBI as a transmitter. Setting to “0”
configures the SBI as a receiver.
At the slave mode, the SBI receives the direction bit ( R/ W ) from the master device on the
following occasions:
• when data is transmitted in the addressing format
• when the received slave address matches the value specified at I2CCR
• when a general-call address is received; i.e., the eight bits following the start
condition are all zeros
If the value of the direction bit ( R/ W ) is “1,” is set to “1” by the hardware. If the bit is
“0,” is set to “0”.
As a master device, the SBI receives acknowledgement from a slave device. If the direction
bit of “1” is transmitted, is set to “0” by the hardware. If the direction bit is “0,”
changes to “1.” If the SBI does not receive acknowledgement, retains the previous
value.
is cleared to “0” by the hardware when it detects the stop condition on the bus or the
arbitration lost.
10.5.7 Generating Start and Stop Conditions
SCL line
SDA line
Start condition
When SBIxSR is “0,” writing “1” to SBIxCR2 causes the SBI to
generate the start condition on the bus and output 8-bit data. must be set to “1” in
advance.
1
A6
Fig. 10-10 Generating the Start Condition and a Slave Address
When is “1,” writing “1” to and “0” to causes the SBI to start
a sequence for generating the stop condition on the bus. The contents of should not be altered until the stop condition appears on the bus.
SCL line
SDA line
2 3 4 5 6 7 8 9
A5 A4 A3 A2 A1 A0 R/W
Slave address and direction bit
Stop condition
Fig. 10-11 Generating the Stop Condition
Acknowledgement
signal
SBIxSR can be read to check the bus state. is set to “1” when the start
condition is detected on the bus (the bus is busy), and set to “0” when the stop condition is
detected (the bus is free).
Serial Bus Interface (SBI)