;From: andrew.mcmeikan at mitswa.com.au
;be carefull when assembling
;there is a lookup table that MUST NOT cross a
;256 byte boundry ---- CHECK IT
LIST P=16C84, F=INHX8M
;thermal printer controler
innerloop = 0ff
lilloop = 01
bigloop =0ff
strobe macro bt
bsf 0x13,bt ;bit for strobe
bcf 0b,7 ;dont want interupts
call outsr ;clock it out
call lildly ;let it burn in
bsf 0b,7 ;re-enable interupts
bcf 0x13,bt ;so next outsr clears it
endm
ORG 0x0000
GOTO main
ORG 0x0004
;entry occurs in here when host pulls strobe signal low
;to indicate data that requires printing
;useing this int routine occupies two levels of stack
;one for the return address and one for outsr's return
;centronics pinouts
; pin 1 strobe is connected to RB0
; pin 2 data1 " " RA1
; pin 3 data2 " " RA2
; pin 4 data3 " " RA3
; pin 5 data4 " " RA4
; pin 6 data5 " " RB1
; pin 7 data6 " " RB2
; pin 8 data7 " " RB3
; pin 9 data8 " " RB4
; pin10 ack " " Cap from BSY this dips low
; when want next byte
; pin11 busy is connected to RA0 High= offline
; pin12 Paper out is connected to photocell High=no paper
;pins 19 to 30 are signal grounds GND
; pin31 INT is connected to RESET (via diode)
; and is used to initialize printer
movwf 0c ;save 'W' in reg file 0c
swapf 3,w ;grab the flags
movwf 0d ;in reg 'd'
;should now be safe to continue!
bsf 5,0 ;say we are busy
;read both ports to get byte of data
rrf 5,w ;read port a shifting data down one
andlw 0f ;only keep bottom bits
movwf 0x16 ;keep incomming data here
rrf 6,w ;read port b shifting down one
andlw 0f ;wipe out extraneous bits
movwf 0x17 ;waste another register
swapf 0x17,w ;get 'b' data lower into upper W
iorwf 0x16,f ;or top bits into data
;bit pattern from host now in 0x16
incf 0e,f ;increment our count of bytes
;clock data into thermal head
movlw 08 ;for 8 bits
movwf 0x17 ;better keep count of it
clkhd: rlf 0x16,f ;rotate it thru carry
bsf 0x12,4 ;set data high
btfss 3,0 ;check the carry flag
bcf 0x12,4 ;clear data if required
call outsr
bsf 0x12,5 ;clock that bit in
call outsr
bcf 0x12,5 ;drop clock again
call outsr
decfsz 0x17,f ;have we finished loop yet ?
goto clkhd ;guess not
;no point doing the extra shift as we are just
;throwing the data away once it is in the head
;if byte count=max then lets latch and let the main routine
; print it
movlw 0xc0 ;try 192 ;216 max bytes per line 1728 bits
subwf 0e,w ;check max against our byte count
btfss 3,2 ;the same? result of zero?
goto continue ;no its ok, head not full yet
;need to latch thermal head
; We do not not lower busy here
;as main routine will do so once it has reset
;the counter.
bsf 0x12,6 ;latch bit for thermal head
call outsr ;send- no one else better be using it
bcf 0x12,6 ;put back
call outsr ;send that to
goto exint ;leave int handler
continue: ;tell host we are no longer busy, get next byte
bcf 5,0 ;bring BSY low
;and fall thru to exit :)
exint: ;now restore to before interupt
swapf 0d,w ;put flags back in order in W
movwf 3 ;stickem bick in flags
swapf 0c,f ;flip saved W
swapf 0c,w ;flip it back into W
bcf 0b,1 ;clear INTF flag so we can get more
RETFIE
main ;thermal printer control program 192 dpi 9 inch 1728 pixels
;need to set up direction bits for ports
;and set initial pin levels
movlw 0 ;pullups and interrupt on neg edge
option ;set options
movlw 0ff
movf 5,f ;set all pins high on port a
movlw 0fe ;RA0 as output
tris 5 ;porta as input except RA0
movlw 01f ;make bits 6,7 &5 low
movf 6,f
movlw 01f ;port b 5,6,7 as output
tris 6 ;make it so !
movlw 08 ;specify which phase to start on
movwf 0x15 ;store it somewhere safe
clrf 0e ;zero byte count for head
movlw 00 ;phases off clk,lat,data, strb off
movwf 0x12 ;data for shift reg 1
movlw 00 ;all strobes off (low)
movwf 0x13 ;data for shift reg 2
call outsr ;set all pins high except for stepper
movlw 0x90 ;enable RB0 and GIE interupt bits
movwf 0b ;interupts now turned on!
bcf 5,0 ;say we are not busy
p1=8;9 ;1
p2=4;8 ;3 ;ok here are definitions of how the shift registers are wired
p3=2;0c;2 ; ok on 0x12 bit0 stepper phase A
p4=1;4 ;6 ; bit1 " " B
p5=8;6 ;4 ; bit2 " " C
p6=4;2 ;0c ; bit3 " " D
p7=2;3 ;8 ; bit4 Data for thermal head
p8=1;1 ;9 ; bit5 Clock for thermal Head
; bit6 Latch for thermal head
; bit7 strobe 1 for thermal head
; 0x13 bit0 to bit7 rest of strobes for head
mloop: ;this is the loopy bit of main
;we sit in here till we get a full head
;then we reset the counter, send an ack to the host
;print the line out and advance the paper, then we sit until
;the head is full again :)
;first check if the head is full
movlw 0xc0 ;try 192 ;216 max bytes per line 1728 bits
subwf 0e,w ;check max against our byte count
btfss 3,2 ;the same? result of zero?
goto mloop ;no not yet keep waiting
clrf 0e ;Ok we've spotted the head full
;need to strobe head drivers
bsf 0x12,7 ;strb1
bcf 0xb,7 ;turn off interupts
call outsr ;Fire!
call lildly ;let it burn!
bsf 0b,7 ;re-enable interupts
bcf 0x12,7 ;ok thats done
strobe 0
strobe 1
strobe 2
strobe 3
strobe 4
strobe 5
strobe 6
strobe 7
bcf 0b,7 ;turn off interupts
call outsr ;yay! all strobes Fired!
bcf 5,0 ;ok we aren't busy any more
bsf 0b,7 ;re-enable interupts
call papadv ;move paper on to next line
goto mloop ;lets go back and see if another
;line is ready yet
phlook: ;this routine looks up the value for a particular phase
;important that this lookup resides within a 256 byte block
;as PCL is directly modified. if called with value grater
;than 8 ,will cause who knows what kind of crash!
addwf 02,f ;ok now its going to jump :)
nop ;err dont expect zero ?!?!
retlw p8 ;return with phase 8
retlw p7 ;coz we are counting down
retlw p6 ;remember... see next routine!
retlw p5
retlw p4
retlw p3
retlw p2
retlw p1
sleep ;coz its all gone wrong if it
;gets here or past!
;check the listing to be sure
;it fits between page boundries!
papadv: ;this routine is to activate a paper advance one step
;it will use register #15 to keep track of which
;point in the phase cycle it is
movlw 0f0 ;prep mask
bcf 0b,7 ;diable interupts
andwf 0x12,f ;nock off bottom bits
movf 0x15,w ;grab our phase number into W
call phlook
iorwf 0x12,f ;new pattern now set
bsf 0b,7 ;ints re-enabled
decf 0x15,f ;get next phase number
btfsc 3,2 ;did we hit zero?
goto recount ;yep need to reload the counter
bcf 0b,7 ;turn off interupts coz of (outsr)
call outsr ;jump to out put new phase
bsf 0b,7 ;turn on interupts again
return ;and go back
recount: movlw 08 ;we hit zero reset it back to 8
movwf 0x15 ;use it next time round
bcf 0b,7 ;clear interupt enable
call outsr ;I know its just below us
bsf 0b,7 ;but tis only way to keep
return ;the interupts rightly enabled
outsr: ;this routine takes bytes at 0x12 and 0x13
;and clocks them out onto the shift registers
;shift registers accessed on port b bits 5,6 & 7
;bit 6 as clock - clocks data on POSITIVE edge
;bit 7 as data - non inverted
;bit 5 as strobe - latches data on NEGATIVE edge
; we are sending lsb first ie bit# 1 on shift register
; output pin #8
; sending byte at address 0x12 first then 0x13
; this puts 0x12 on the last shift register in line
;uses reg # 14 to keep count of bits
;since this code is NON-RE-ENTERENT, do NOT call it
;while interupts are enabled, coz the int handler
;calls this routine to access the thermal head.
movlw 08 ;for 8 bits
movwf 0x14 ;better keep count of it
shiftbits: rrf 0x12,f ;rotate it thru carry
bsf 6,7 ;set data high
btfss 3,0 ;check the carry flag
bcf 6,7 ;clear data if required
bsf 6,6 ;clock that bit in
bcf 6,6 ;drop clock again
decfsz 0x14,f ;have we finished loop yet ?
goto shiftbits ;guess not
rrf 0x12,f ;preserve the data, shift the carry
;now we have finished one byte lets do the other
movlw 08 ;for 8 bits
movwf 0x14 ;better keep count of it
shiftbitsagain: rrf 0x13,f ;rotate it thru carry
bsf 6,7 ;set data high
btfss 3,0 ;check the carry flag
bcf 6,7 ;clear data if required
bsf 6,6 ;clock that bit in
bcf 6,6 ;drop clock again
decfsz 0x14,f ;have we finished loop yet ?
goto shiftbitsagain ;guess not
rrf 0x13,f ;preserve the data, shift the carry
;now we have really finished clocking bits
bsf 6,5 ;bring up the strobe line
bcf 6,5 ;and LATCH it
return ;back to where ever.
lildly movlw lilloop
movwf 0x11
goto reload
bigdly MOVLW bigloop
MOVWF 0x11
reload MOVLW innerloop
MOVWF 0x10
inloop NOP
DECFSZ 0x10 , f
GOTO inloop
DECFSZ 0x11 , f
GOTO reload
RETURN
ORG 0X2000
DATA 00
DATA 00
DATA 00
DATA 00
ORG 0x2007
DATA 0x19 ;fuse settings
org 0x2100
;data 00
;data 00
;data 00
END
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