MS51
Nov. 28, 2019 Page 415 of 491 Rev 1.00
MS51 32K SERIES TECHNICAL REFERENCE MANUAL
Slave Receiver
In the slave receiver mode, several bytes of data are received form a master transmitter. Before a
transmission is commenced, I2CnADDRx should be loaded with the address to which the device will
respond when addressed by a master. I2CnCLK does not affect in slave mode. The AA bit should be
set to enable acknowledging its own slave address. After the initialization above, the I
2
C idles until it is
addressed by its own address with the data direction bit “write” (SLA+W). The slave receiver mode
may also be entered if arbitration is lost.
After the slave is addressed by SLA+W, it should clear its SI flag to receive the data from the master
transmitter. If the AA bit is 0 during a transaction, the slave will return a non-acknowledge after the
next received data byte. The slave will also become not addressed and isolate with the master. It
cannot receive any byte of data with I2CnDAT remaining the previous byte of data, which is just
received.
Slave Transmitter
The I
2
C port is equipped with four slave address registers, I2CnADDRx (x=0~3). The contents of the
register are irrelevant when I
2
C is in Master mode. In the slave transmitter mode, several bytes of data
are transmitted to a master receiver. After I2CnADDRx and I2CnCON values are given, the I
2
C wait
until it is addressed by its own address with the data direction bit “read” (SLA+R). The slave
transmitter mode may also be entered if arbitration is lost.
After the slave is addressed by SLA+R, it should clear its SI flag to transmit the data to the master
receiver. Normally the master receiver will return an acknowledge after every bytes of data is
transmitted by the slave. If the acknowledge is not received, it will transmit all “1” data if it continues
the transaction. It becomes a not addressed slave. If the AA flag is cleared during a transaction, the
slave transmits the last byte of data. The next transmitting data will be all “1” and the slave becomes
not addressed.
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