MC68000 MOTOROLA [Motorola, Inc], MC68000 Datasheet - Page 372

• Manufacturer Part Number: MC68000
• Manufacturer: MOTOROLA [Motorola, Inc]

MC68302 Applications
D-22
* The Tx BD sand data status is not checked since the only one is CTS lost,
* which is not applicable, since CTS is ignored in this application.
* The following updates A2 to point to the next Tx BD
REINIT2 MOVEA.L
* Determine what the next byte to “echo” will be and then go to OUTERLOOP
NEWA1
* The two lines with ***
* If the number is increased, these values should be increased by the same
* amount. These are the only lines dependent on the Rx BD or Tx BD setup.
***************************************************************************
* SC C3 I nt er r up t R o u ti n e
* Test Break:
BRKTEST
*Test Receive:
RECTEST
* Busy handler:
BUSY
*Break handler:
BREAK
* The UART BRKEC will record the number of breaks received
*Receive handler:
RECEIVE
INCPTR
CONT
BSET.B
BTST.B
BNE.B
ADDA.W
BRA.B
ADDO.W
CMPA.L
BEQ.B
BRA.B
SUBO.W
BRA.B
ORG
CLR.L
MOVE.B
MOVE.B
BTST.B
BNE.B
BTST.B
BNE.B
BTST.B
BNE.B
JMP
ADDQ.B
BSET.B
JMP
NOP
JMP
ADDQ.W
ADDQ.B
ADDQ.W
CMPI.B
BNE.B
SUBQ.W
ANDI.W
#$7,(A2)
#$05,(A2)
REINIT2
#$08,A2
CONT
#$700640,A2
#$1,A1
#$30004,A1
NEWA1
OUTLOOP
#$02.A1
OUTLOOP
$30500
D1
SCCE3,D1
#$15,SCCE3
#$2.D1
BUSY
#$4,D1
BREAK
#$0,D1
RECEIVE
ALMDONE
#1,D5
#$F,(A0)
BRKTEST
RECTEST
#1,D3
#1,D6
#1,A0
#$0,(A0)
BSTAT
#1,A0
#$FF00,(A0)
MC68302 USER’S MANUAL
above are dependent on the number of Rx BDs used.
;Set Ready bit of Tx BD
;test Wrap bit
;If set, reinit A2 to 700640
;else inc A2 by 8 to next Tx BD
;Jump to Continue on
;Reinitialize A2
;Increment A1 to next byte to send
;Is A1 = 30004? ***
;If so, go to NEWA1
;Jump back to outerloop and wait
;Set A1 back to 30002 ?***
;Jump back to outerloop and wait
;clear D1
;Move SCCE3 status to D1
;Clear only BRK. BSY and RX in SCCE3.
;Is BSY set?
;Jump to BUSY handler if set
;Is BRK set?
;Jump to BREAK handler if set
;Is RX set?
;Jump to RECEIVE handler if set
;Jump to About Done (impossible)
;Inc Busy counter (no receive buffers)
;set Empty bit of current Rx BD
;Jump to test for BREAK
;This code ignores received breaks
;Jump to test for RECEIVE
;Increment number of chars received
;D6 inc by 1 (character ready to send)
;Inc A0 to point to Rx BD byte status
;Does status = 00?
;Jump to Bad Status it not 00
;Dec A0 to point to beginning of Rx BD
;Clear out Rx BD status
MOTOROLA