MC68000 MOTOROLA [Motorola, Inc], MC68000 Datasheet - Page 371

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

MOTOROLA
* of idles are received without a new * character. Note that 0 is the maximum
* value. In this case the buffer will always be closed after 1 character, so
* MAX_IDL is a don't care.
* STOP TRANSMIT command executed. The STOP TRANSMIT command is not used in
* this code.
* Initialize counters to zero
* UART Address characters not used in normal operation.
* Initialize CHARACTER8
* No control characters are initialized to cause special interrupts.
* The flow-control facility (XON-XOFF) is not used.
*Interrupts in SCCM3 are allowed only for BRK (break character
*received), BSY (no receive buffer available), and RX (buffer
* received). Note that buffers are 1 character in this application.
* Set ENR and ENT bib in SCM3.
***************************************************************************
* Tr ans mit C od e
* OUTERLOOP
OUTLOOP
* INNERLOOP:
INLOOP
* The following sets up and sends out the transmit buffer
MOVE.W
MOVE.W
MOVE.W
MOVE.W
MOVE.W
MOVE.W
MOVE.W
MOVE.W
MOVE.W
MOVE.B
MOVE.B
MOVE.W
MOVE.W
CLR.L
CLR.L
CLR.L
CLR.L
CLR.L
CLR.L
MOVEA.L
MOVEA.L
MOVEA.L
MOVE.W
CMPI.B
BEQ.B
SUBQ.B
BTST.B
BNE.B
ADDO.W
MOVEA.L
ADDQ.W
MOVEA.L
MOVE.B
ADDQ.W
MOVE.W
SUBO.W
#$1,$7006A0
#$0,$7006A2
#$0,$7006A4
#$0,$7006A6
#$0,S7006A8
#$0,$7006aa
#$0,$7006ac
#$8000,$7006B0
#$0000,$7006BE
#$FF,SCCE3
#$15,SCCM3
#$0100,1MR
#$17d,SCM3
D0
D1
D3
D4
D5
D6
#$700600,A0
#$30002,A1
#$700640,A2
#$2000,SR
#$0,D6
OUTLOOP
#$1,D6
#$07,(A2)
INLOOP
#$1,D4
A2,A3
#$4,A3
(A3),A3
(A1),(A3)
#2,A2
#$1,(A2)
#2,A2
MC68302 USER’S MANUAL
;BRKCR = 1. Only one break char. sent if
;PAREC = 0000
;FRMEC = 0000
;NOSEC = 0000
;BRKEC = 0000
;UADDR1 = 0000
;UADDR2 = 0000
;CHARACTER1 = 8000
;CHARACTER8 = 0000
;clear SCCE3
;SCCM3 = 15
;IMR=0100. Allow SCC3 interrupts only.
;SCM3 = 017d
;clear all used data registers
;Load A0 as current Rx BD pointer
;Load A1 as current “next Tx Byte” ptr
;Load A2 as current Tx BD pointer
;Enable interrupts. Stay in spvr mode.
; Something to send (is D6> =1?)
; Stay in outerloop if 0
; Decrement send status by 1 (0 = empty)
; Test Ready bit of Tx BD
; Fall thru if 0, else wait in innerloop
; Increment number of chars transmitted
; A3 will be used to find Tx data buffer
; Inc A3 to point to Tx data pointer
; A3 now points to Tx Data buffer
; Move char from Rx Buffer to Tx Buffer
; Increment A2 to point to byte count
; Set TxBD Byte count to 1
; A2 now points to beginning of Tx BD
MC68302 Applications
D-21