N76E885 Datasheet, PDF (92/196 Pages) List of Unclassifed Manufacturers – Microcontroller

N76E885 Datasheet
continued by the winning master. However, the arbitration lost master continues generating clock
pulses on SCL line until the end of the byte in which it loses the arbitration.
Arbitration is carried out by all masters continuously monitoring the SDA line after outputting data. If
the value read from the SDA line does not match the value that the master has to output, it has lost
the arbitration. Note that a master can only lose arbitration when it outputs a high SDA value while
another master outputs a low value. Arbitration will continue until only one master remains, and this
may take many bits. Its first stage is a comparison of address bits, and if both masters are trying to
address the same device, arbitration continues on to the comparison of data bits or acknowledge bit.
DATA 1 from master 1
DATA 2 from master 2
Master 1 loses arbitration for DATA 1 ≠ SDA
It immediately switches to not addressed slave
and outputs high level
SDA line
SCL line
START
condition
Figure 16-6. Arbitration Procedure of Two Masters
2
Since control of the I C bus is decided solely on the address or master code and data sent by
competing masters, there is no central master, nor any order of priority on the bus.
Slaves are not involved in the arbitration procedure.
16.2 Control Registers of I²C
2
There are five control registers to interface the I C bus including I2CON, I2STAT, I2DAT, I2ADDR, and
I2CLK. These registers provide protocol control, status, data transmitting and receiving functions, and
clock rate configuration. The following registers relate to I²C function.
Dec. 21, 2015
Page 92 of 196
Rev. 1.01