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I may have to move this to a file in the gallery.
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AVRASM ver. 2.1.9 E:\avr\mega8inkchip\RWchip.asm Sun Sep 28 10:56:20 2008
E:\avr\mega8inkchip\RWchip.asm(2): Including file 'E:\avr\mega8inkchip\m8def.inc'
.list
.CSEG
; working registers for the program.
.def EEdata = r13
.def EEPending = r14
.def chipId = r15
.def temp = r16
.def counter1 = r17 ; counters for various routines.
.def EEcount = r18
.def counter2 = r19
.def counter0 = r20
.def count = r21 ; Bit counter
.def serbyte = r22
.def work1 = r23
.def EEindex = r24
.def SyncFlag = r25
.MACRO led1on
cbi PORTC,PB2 ; LED ON
.ENDMACRO
.MACRO led1off
sbi portc,PB2 ; LED OFF
.ENDMACRO
.MACRO led2on
sbi PORTD,PB2 ; LED ON
.ENDMACRO
.MACRO led2off
cbi portD,PB2 ; LED OFF
.ENDMACRO
;Reset vector (must be the first code generated)
000000 c00b rjmp RESET ; Reset Handler
000001 9518 reti ; Ext Interrupt 0 Handler (not used)
000002 9518 reti ; Ext Interrupt 1 Handler (not used)
000003 9518 reti ; Timer1 Capture Handler
000004 9518 reti ; Timer1 Compare Handler
000005 9518 reti ; Timer1-B compare Handler (not used)
000006 9518 reti ; Timer1 Overflow Handler (not used)
000007 9518 reti ; Timer0 Overflow Handler
000008 9518 reti
000009 9518 reti
00000a 9518 reti
00000b 9518 reti
;-----------------------------------------------------------------
; code starts executing here on reset
RESET:
00000c 98a4 cbi dataddr,data0bit;
00000d 98a5 cbi dataddr,data1bit;
00000e 98ac cbi dataport,data0bit;
00000f 98ad cbi dataport,data1bit;
000010 e50f ldi temp,LOW(RAMEND) ; set the stack pointer
000011 bf0d out SPL, temp
000012 e004 ldi temp,HIGH(RAMEND)
000013 bf0e out SPH, temp
000014 9aa2 sbi DDRC,PB2 ; Enable led driver.
000015 9a8a sbi DDRD,PB2 ; Enable led driver.
000016 9aaa led1off
000017 9892 led2off
; Work out chip ID from EEPROM data.
000018 e38f ldi EEindex,$3f // the ID bits are in eeprom cell x3f
000019 d0a3 rcall readee // read the eeprom.
00001a 9506 lsr temp // move the ID bit into the bottom 3 bits.
00001b 9506 lsr temp
00001c 9506 lsr temp
00001d 9506 lsr temp
00001e 7007 andi temp,7 // this shouldn't be needed.
00001f 2ef0 mov chipId,temp // mov the ID into another register where it stays forever.
wait4sync:
000020 d094 rcall waitsyncPL // if sync is low wait.
// led1on
000021 d063 rcall getnib // get the three ID bits and the R/W bit.
000022 2399 tst SyncFlag // see if sync went low before nib was recieved.
000023 f449 brne waitchip2 // sync was low back to start
000024 2d7f mov work1,chipId // get chip ID from low register to working register.
000025 1707 cp temp,work1 // compare - will be equal if ID matches and R/W = read mode.
000026 f411 brne notreadID // if not equal we jump to test for write mode.
000027 d035 dosend: rcall senddata // The ID etc match so we call the rountine to dump the EEPROM data to the printer.
000028 c004 rjmp waitchip2 // finished - possibly due to sync going low. Return to start.
notreadID: // check for ID+write bit
000029 6078 ori work1,0x8 // add the write bit to our ID
00002a 1707 cp temp,work1 // compare again.
00002b f409 brne waitchip2 // if not equal go back to start
00002c d002 rcall data2eeprom // was equal so call write eeprom rountine.
// rjmp waitchip2 // finished - possibly due to sync going low. Return to start.
waitchip2:
00002d d08b rcall waitsyncNL // wait for sync to go low (if it isn't already) before looping back.
00002e cff1 rjmp wait4sync
;--------------------------------------------------------------------------------------------------------
; Note the printer usually only writes a few bytes. The 32 byte write happens in the external chip writer.
data2eeprom: // Stored data to the EEPROM till 32 bytes are stored or sync goes low.
00002f 98aa led1on
000030 24ee clr EEpending
000031 e280 ldi EEindex,$20 // This is where the data lives in the EEPROM.
000032 e220 ldi EEcount,$20 // This is the maximum number of bytes to store.
// ldi EEcount,$3 // This is the maximum number of bytes to store.
eewrtloop:
getbyte: ; get byte from serial stream return type in temp or ff in temp if timeout etc
000033 2766 clr serbyte // clear sync flag register
000034 d03f rcall waitclkPE // wait for clk high edge, data bit in temp and sync flag returned
000035 2399 tst SyncFlag // test for sync low.
000036 f4a1 brne abortGB // if low return.
000037 20ee tst EEpending
000038 f019 breq notpending
000039 d01a rcall EEWrite // data byte was pending call EEPROM write rountine.
00003a 24ee clr EEpending
00003b 9583 inc EEindex // Inc index to next address
notpending:
00003c 9566 lsr serbyte // shift the shifter
00003d 7100 andi temp,1< carry
0000ab f410 brcc OutLow // if carry clear jump to "output a low"
0000ac 9aac sbi dataport,data0bit // we are sending a one so set output pin high.
0000ad c001 rjmp DecOutCount // go to loop counting code.
OutLow:
0000ae 98ac cbi dataport,data0bit // output a low - set pin low.
DecOutCount:
0000af dfea rcall waitclkNE // wait for a clock edge or sync low.
0000b0 2399 tst SyncFlag // was sync low.
0000b1 f411 brne abort // yes it was low leave loop and return.
0000b2 953a dec counter2 // dec counter
0000b3 f7b1 brne OutLoop // if non-zero repeat loop
0000b4 9508 abort: ret // either the byte was sent or sync went low - return.
;--------------------------------------------------------------------------------------------------------
waitsyncPL: ; look for positive LEVEL of "sync" line - not the clock.
0000b5 b300 in temp,syncpin
0000b6 7400 andi temp,1<