MC68HC12 MOTOROLA [Motorola, Inc], MC68HC12 Datasheet - Page 321

• Manufacturer Part Number: MC68HC12
• Description: The MC68HC912DT128A microcontroller unit (MCU) is a 16-bit device composed of standard on-chip peripherals including a 16-bit central processing unit
• Manufacturer: MOTOROLA [Motorola, Inc]

17.7.5 Generation of Repeated START
17.7.6 Slave Mode
MC68HC912DT128A — Rev 4.0
MOTOROLA
be done by setting the transmit acknowledge bit (TXAK) before reading
the 2nd last byte of data. Before reading the last byte of data, a STOP
signal must be generated first. The following is an example showing how
a STOP signal is generated by a master receiver.
At the end of data transfer, if the master still wants to communicate on
the bus, it can generate another START signal followed by another slave
address without first generating a STOP signal. A program example is
as shown.
In the slave interrupt service routine, the module addressed as slave bit
(IAAS) should be tested to check if a calling of its own address has just
been received (see
transmit/receive mode select bit (Tx/Rx bit of IBCR) according to the
R/W command bit (SRW). Writing to the IBCR clears the IAAS
automatically. Note that the only time IAAS is read as set is from the
interrupt at the end of the address cycle where an address match
occurred, interrupts resulting from subsequent data transfers will have
IAAS cleared. A data transfer may now be initiated by writing information
to IBDR, for slave transmits, or dummy reading from IBDR, in slave
RESTART
MASR
LAMAR
ENMASR
NXMAR
DEC
BEQ
MOVB
DEC
BNE
BSET
BRA
BCLR
MOVB
RTI
BSET
MOVB
Inter IC Bus
IBCR,#$04
CALLING,IBDR
Figure
RXCNT
ENMASR
RXCNT,D1
D1
NXMAR
IBCR,#$08
NXMAR
IBCR,#$20
IBDR,RXBUF
17-4). If IAAS is set, software should set the
;DECREASE THE RXCNT
;LAST BYTE TO BE READ
;CHECK SECOND LAST BYTE
;TO BE READ
;NOT LAST OR SECOND LAST
;SECOND LAST, DISABLE ACK
;TRANSMITTING
;LAST ONE, GENERATE ‘STOP’ SIGNAL
;READ DATA AND STORE
ANOTHER START (RESTART)
;TRANSMIT THE CALLING ADDRESS
;D0=R/W
IIC Programming Examples
Technical Data
Inter IC Bus
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