📄 chap3.asm
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; Chapter 3 6812 assembly language programs; Jonathan W. Valvano; This software accompanies the book,; Real Time Embedded Systems published by Brooks Cole;; Program 3.3. Assembly language routines to initialize and output to a printer.; MC68HC812A4; PortJ is DATA, PH0=GOInit ldaa #$FF staa DDRJ ;outputs ldaa #$01 staa DDRH staa PORTH ;GO=1 rtsOut staa PORTJ ;set data ldaa #0 staa PORTH ;GO=0 ldaa #1 staa PORTH ;GO=1 ldd #16000OLoop subd #1 ; [2] bne OLoop ; [3] rts; Program 3.6. 6811 or 6812 assembly language routine to create an accurate time delay.; 6811 or 6812; Reg D is the number of cycles to wait; can range from 25 to 32767Wait addd TCNT time at the end of delayLoop cpd TCNT wait for Endt-TCNT>0 bpl Loop rts; Program 3.8. Assembly language routines to initialize and read from an A/D.; MC68HC812A4; PortJ is DATA, PH0=GOInit clr DDRJ ldaa #$FF staa DDRH clr PORTH ;GO=0 rtsIn ldaa #1 staa PORTH ;GO=1 clr PORTH ;GO=0 ldaa #10loop deca ;[1] bne loop ;[3] lda PORTJ rts; Program 3.10. Assembly language routines to initialize and read from a keyboard.; MC68HC812A4; PJ6-0 is DATA, PJ7=STROBEInit clr DDRJ ldaa #$80 ;rise on PJ7 staa KPOLJ ;key wakeup staa KWIFJ ;clear flag rtsIn brclr KWIFJ,$80,In ldaa #$80 staa KWIFJ ;clear flag ldaa PORTJ anda #$7F rts; Program 3.12. Assembly language routines to initialize and read from an A/D.; MC68HC812A4; PortH=DATA PJ1=DONE PJ0=GOInit ldaa #$01 ;PJ1 input staa DDRJ ;PJ0 output ldaa #$02 ;rise on PJ1 staa KPOLJ ;key wakeup clr DDRH ;PA inputs clr PORTJ ;GO=0 rtsIn ldaa #$02 staa KWIFJ ;clear flag ldaa #1 staa PORTJ ;GO=1 clr PORTJ ;GO=0;wait for rise of DONELoop brclr KWIFJ,$02,Loop ldaa PORTH rts; Program 3.14. Handshaking assembly language routines to initialize and read from a sensor.; MC68HC812A4; PortH=DATA PJ1=READY PJ0=ACKInit ldaa #$01 ;PJ1 input staa DDRJ ;PJ0 output ldaa #$02 ;rise on PJ1 staa KPOLJ ;key wakeup ldaa #$02 staa KWIFJ ;clear flag1 clr DDRH ;PH inputs ldaa #$01 staa PORTJ ;ACK=1 rtsIn brclr KWIFJ,$02,In clr PORTJ ;ACK=0 ldaa PORTH ;read DATA ldab #$02 stab KWIFJ ;clear flag inc PORTJ ;ACK=1 rts; Program 3.17. Handshaking assembly language routines to initialize and write to a printer.; MC68HC812A4; PortH=DATA PJ1=READY PJ0=ACKInit ldaa #$01 ;PJ1 input staa DDRJ ;PJ0 output ldaa #$02 ;rise on PJ1 staa KPOLJ ;key wakeup ldaa #$02 staa KWIFJ ;clear flag ldaa #$FF staa DDRH ;PH outputs ldaa #$01 staa PORTJ ;START=1 rtsOut ldab #$02 stab KWIFJ ;clear flag clr PORTJ ;START=0 staa PORTH ;write DATA inc PORTJ ;ACK=1Wait brclr KWIFJ,$02,Wait rts; Program 3.19. Assembly language initialization of the DS1620; MC68HC812A4/MC68HC912B32; PS7=RST PS6=CLK PS5=DQInit ldaa #$E0 ;PD5-3 output staa DDRS ldaa #$60 ;RST=0,CLK=1 staa PORTS ;DQ=1 rts; Program 3.21. Assembly language helper functions for the DS1620; MC68HC812A4/MC68HC912B32out8 ldab #8 ;8 bitsclop bclr PORTS,#$40 ;CLK=0 lsra ;lsb first bcc set0 bset PORTS,#$20 ;DQ=1 bra nextset0 bclr PORTS,#$20 ;DQ=0next bset PORTS,#$40 ;CLK=1 decb bne clop rtsstart bset PORTS,#$80 ;RST=1 ldaa #$EE bsr out8 bclr PORTS,#$80 ;RST=0 rtsstop bset PORTS,#$80 ;RST=1 ldaa #$22 bsr out8 bclr PORTS,#$80 ;RST=0 rts; Program 3.23. Assembly language functions to set the configuration register on the DS1620; MC68HC812A4/MC68HC912B32config psha bset PORTS,#$80 ;RST=1 ldaa #$0C bsr out8 pula bsr out8 bclr PORTS,#$80 ;RST=0 rts; Program 3.25. Assembly language 9-bit output helper function for the DS1620; MC68HC812A4/MC68HC912B32out9 ldx #9 ;9 bitsolop bclr PORTS,#$40 ;CLK=0 lsrd ;lsb bcc oset0 bset PORTS,#$20 ;DQ=1 bra nextoset0 bclr PORTS,#$20 ;DQ=0onext bset PORTS,#$40 ;CLK=1 dex bne olop rts; Program 3.26. Assembly language functions to set the threshold registers on the DS1620; MC68HC812A4/MC68HC912B32;Reg D is temperature valueWriteTH pshd bset PORTS,#$80 ;RST=1 ldaa #$01 bsr out8 puld bsr out9 bclr PORTS,#$80 ;RST=0 rts;Reg D is temperature valueWriteTL pshd bset PORTS,#$80 ;RST=1 ldaa #$02 bsr out8 puld bsr out9 bclr PORTS,#$80 ;RST=0 rts; Program 3.28. Assembly language functions to read the configuration register on the DS1620; MC68HC812A4/MC68HC912B32;input 8 bits, Reg A=datain8 ldx #8 ;8 bits ldaa DDRD anda #$DF ;DQ input staa DDRDilop bclr PORTS,#$40 ;CLK=0 lsra ;lsb brclr PORTS,#$20,inext oraa #$80 ;DQ=1inext bset PORTS,#$40 ;CLK=1 dex bne ilop ldab DDRS orab #$20 ;DQ output stab DDRS rts;Reg A is config valueReadConfig bset PORTS,#$80 ;RST=1 ldaa #$AC bsr out8 bsr in8 bclr PORTS,#$80 ;RST=0 rts; Program 3.29. Assembly language 9-bit read helper function for the DS1620; MC68HC812A4/MC68HC912B32;input 9 bits, Reg D=datain9 ldx #9 ;9 bits ldaa DDRD anda #$DF ;DQ input staa DDRD clrajlop bclr PORTS,#$40 ;CLK=0 lsrd ;lsb brclr PORTS,#$20,jnext oraa #$01 ;DQ=1jnext bset PORTS,#$40 ;CLK=1 dex bne ilop ldab DDRS orab #$20 ;DQ output stab DDRS rts; Program 3.30. Assembly language functions to read the temperatures from the DS1620; MC68HC812A4/MC68HC912B32;Reg D returned as TH valueReadTH bset PORTS,#$80 ;RST=1 ldaa #$A1 bsr out8 bsr in9 bclr PORTS,#$80 ;RST=0 rts;Reg D returned as TL valueReadTL bset PORTS,#$80 ;RST=1 ldaa #$A2 bsr out8 bsr in9 bclr PORTS,#$80 ;RST=0 rts;Reg D returned as temperatureReadT bset PORTS,#$80 ;RST=1 ldaa #$AA bsr out8 bsr in9 bclr PORTS,#$80 ;RST=0 rts⌨️ 快捷键说明
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