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\ history: last revision first ALL 14:07 28AUG95
\ ALL950828 V0.06 first release
\ ....
\ ALL950112 V0.01 first try
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\ TMEM? DALLAS TOUCHMEMORY ALL 11:53 28AUG95
DECIMAL
ASSEMBLER
P1.5 EQU $PTM \ define TOUCH-MEM DATA port pin
FORTH
HEX 33 EQU cTMRD DECIMAL \ 0F or 33 are read commands
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\ TMEM? DALLAS TOUCHMEMORY present? ALL 21:13 14APR96
CODE TMEM? ( -- t=PRESENT ) \ TM present?
A,# 4 MOV $PTM CLR \ start of RESET pulse LOW
B ,# 250 MOV 1$: B , 1$ DJNZ \ 480..960uSEC->500Tcycles
$PTM SETB \ end of RESET pulse HIGH
B ,# 6 MOV C CLR \ clear CY = NO_presence
2$: $PTM , 3$ JB \ B: HIGH, leave loop
B , 2$ DJNZ \ LOOP for 3360uSEC
ACC , 2$ DJNZ \ if DATA stays LOW
9$ SJMP \ STUCK LOW
3$: B ,# 40 MOV \ 60..240uSEC-> 160Tcycles
4$: C,/ $PTM ORL B , 4$ DJNZ \ delay CY=1=PRESENCE detect
9$: A CLR A,# 0 SUBB R1,A MOV
APUSH LJMP END-CODE
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\ TM><CY TM><bit0 exchange bits w/ DOW ALL 21:14 14APR96
\ 15uS DS2401 window, then MASTER window, 60..120uS total slot
PROC TM><CY \ exchange CY and TMdata bit
B PUSH
$PTM CLR NOP NOP NOP NOP \ start time slot 1..15uSEC
$PTM ,C MOV \ >=1uS ..6T, send CY
B ,# 05 MOV 1$: B , 1$ DJNZ \ ..6+2+10=18Tcycles
C, $PTM MOV \ read DS_DATA ..20Tcycles
B ,# 18 MOV 1$: B , 1$ DJNZ \ 20+2+36=78Tcycles
B POP \ =60..120uSEC =tSLOT
$PTM SETB \ terminate time slot
RET END-PROC
CODE TM><bit0 ( c -- c' ) \ exchange bit0 and TMdata
DP=SP DPL INC A,@DPTR MOVX \ get c -> ACC
A RRC TM><CY LCALL A RLC
@DPTR,A MOVX \ put ACC -> c'
NEXT LJMP END-CODE
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\ TMC><C TMRD TMWR exchange bytes w/ DOW ALL 21:15 14APR96
CODE TM><C ( c -- c' ) \ exchange byte and TMdata
DP=SP DPL INC A,@DPTR MOVX \ get c -> ACC
B PUSH B ,# 8 MOV \ bit count=8
1$: A RRC TM><CY LCALL B , 1$ DJNZ \ send a bit
A RRC \ get final bit
B POP
@DPTR,A MOVX \ put ACC -> c'
NEXT LJMP END-CODE
: TMRD ( -- c ) 255 TM><C ;
: TMWR ( c -- ) TM><C DROP ;
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\ CRC8 =X^8+X^5+X^4+1 ALL 21:17 14APR96
CODE CRC8 ( crc char -- crc' ) DP=SP \ build CRC8
DPL INC A,@DPTR MOVX DPTR INC \ charL ->ACC
R0,A MOV \ -> R0
DPL INC A,@DPTR MOVX R1,A MOV \ crc -> R1
B ,# 8 MOV A,R0 MOV \ B=bit count; A=char
1$: A,R1 XRL A RRC \ CY=char XOR crc.0
A,R1 MOV 2$ JNC \ NC: bit0 was 0
A,# 24 XRL \ 18h feedbacks
2$: A RRC R1,A MOV \ positition new crc
A,R0 MOV A RR R0,A MOV \ next bit to bit0
B , 1$ DJNZ \ NZ: more bits
A,R1 MOV @DPTR,A MOVX DPL DEC \ put crc'
DP=>SP LJMP END-CODE
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\ .tm# TML show DOW/DS2401 data ALL 12:43 31JAN95
\ L. shows low byte as 2 HEX chars
: .tm# TMEM? IF
CR
cTMRD TM><C \ 33h | 0Fh is RD CMD
DROP
0 ( -- cCRC )
8 0 DO TMRD DUP L. CRC8 LOOP
IF 7 EMIT ." CRC error " THEN \ append moaning
THEN
;
: TML BEGIN .tm# ESC? UNTIL ; \ an endless loop shows DOW
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