tmp88cs38ng TOSHIBA Semiconductor CORPORATION, tmp88cs38ng Datasheet - Page 95

• Manufacturer Part Number: tmp88cs38ng
• Description: Cmos 8-bit Microcontroller
• Manufacturer: TOSHIBA Semiconductor CORPORATION

SCL (Bus)
SDA pin (Master 1)
SDA pin (Master 2)
SDA (Bus)
(9) Serial bus interface operating mode selection
(10) Arbitration lost detection monitor
mode.
changing operation mode, confirm serial bus interface pins in a high level. And switch
a mode to port after confirming that a bus is free.
mode, a bus arbitration procedure is implemented in order to guarantee the contents of
transferred data.
devices exist simultaneously on a bus. Master 1 and master 2 output the same data
until point “a”. After master 1 outputs “1” and master 2, “0”, the SDA line of a bus is
wired AND and the SDA line is pulled down to the low level by master 2. When the
SCL line of a bus is pulled up at point “b”, the slave device reads data on the SDA line,
that is data in master 2.
“arbitration lost”. A master device which loses arbitration releases the SDA pin and
the SCL pin in order not to effect data transmitted from other masters with arbitration.
When more than one master sends the same data at the first word, arbitration occurs
continuously after the second word.
The SBIM (Bit3 and 2 in SBICRB) is used to specify a serial bus interface operation
Set the SBIM to “10” in order to change a operation mode to I
Since more than one master device can exist simultaneously on a bus in the I
Data on the SDA line is used for bus arbitration of the I
The following shows an example of a bus arbitration procedure when two master
Data transmitted from master 1 becomes invalid. The state in master 1 is called
Figure 2.9.11 Arbitration Lost
88CS38-95
a
b
SDA pin becomes “1” after losing arbitration.
TMP88CS38/CM38A/CP38A
2
C bus.
2
C bus mode. Before
2007-09-12
2
C bus