mcf5249 Freescale Semiconductor, Inc, mcf5249 Datasheet - Page 340

• Manufacturer Part Number: mcf5249
• Description: Coldfire Integrated Microprocessor
• Manufacturer: Freescale Semiconductor, Inc

Freescale Semiconductor, Inc.
BTST.B #0,(A7)+
BNE.B END
MOVE.B TXCNT,D0;Get value from the transmitting counter
BEQ.S END;If no more data, branch to end
MOVE.B DATABUF,-(A7);Transmit next byte of data
MOVE.B (A7)+,MBDR
MOVE.B TXCNT,D0;Decrease the TXCNT
SUBQ.L #1,D0
MOVE.B D0,TXCNT
BRA.S EMASTX;Exit
END LEA.L MBCR,-(A7);Generate a STOP condition
BCLR.B #5,(A7)+
EMASTX RTE; Return from interrupt
MASR MOVE.B RXCNT,D0;Decrease RXCNT
SUBQ.L #1,D0
MOVE.B D0,RXCNT
BEQ.S ENMASR;Last byte to be read
MOVE.B RXCNT,D1;Check second-to-last byte to be read
EXTB.L D1
SUBI.L #1,D1;
BNE.S NXMAR; Not last one or second last
LAMAR BSET.B #3,MBCR;Disable ACK
BRA NXMAR
ENMASR BCLR.B #5,MBCR; Last one, generate 'STOP'signal
NXMAR MOVE.B MBDR,RXBUF; Read data and store RTE
Generation of Repeated START
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 follows.
RESTART MOVE.B MBCR,-(A7); Another START (RESTART)
BSET.B #2, (A7)
MOVE.B (A7)+, MBCR
MOVE.B CALLING,-(A7);Transmit the calling address, D0=R/W-
MOVE.B CALLING,-(A7);
MOVE.B (A7)+, MBDR
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