Toshiba H1 SERIES TLCS-900 User Manual
Page 183

TMP92CM22
2007-02-16
92CM22-181
(8) Interrupt service requests and interrupt cancellation
When a serial bus interface interrupt request 0 (INTSBE0) occurs, the SBI0SR2
pulled down to the low level.
The
And when writing data to SBI0DBR or reading data from SBI0DBR,
“1”.
The time from the
LOW
.
In the address recognition mode (
= 0),
received slave address is the same as the value set at the I2C0AR or when a GENERAL
CALL is received (All 8-bit data are “0” after a start condition). Although
SBI0CR2
it is programmed “0”.
(9) Serial bus interface operation mode selection
SBI0CR2
SBI0CR2
2
C bus mode after
confirming pin condition of serial bus interface to “H”.
Switch a mode to port after confirming a bus is free.
(10) Arbitration lost detection monitor
Since more than one master device can exist simultaneously on the bus in I
2
C bus
mode, a bus arbitration procedure has been implemented in order to guarantee the
integrity of transferred data.
Data on the SDA line is used for I
2
C bus arbitration.
The following shows an example of a bus arbitration procedure when two master
devices exist simultaneously on the bus. Master A and master B output the same data
until point “a”. After master A outputs “L” and master B, “H”, the SDA line of the bus is
wire-AND and the SDA line is pulled down to the low level by master A. When the SCL
line of the bus is pulled up at point b, the slave device reads the data on the SDA line,
that is, data in master A. A data transmitted from master B becomes invalid. The state
in master B is called “ARBITRATION LOST”. Master B device that loses arbitration
releases the internal SDA output in order not to affect 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.
Figure 3.10.11 Arbitration Lost
Set internal SDA output to “1”
after arbitration has been lost.
a
SCL (Line)
Internal SDA output
(Master A)
SDA line
b
Internal SDA output
(Master B)