;PIC16C84 keybord controller for Amiga keybords
;pressed keys are located in table and send in serial format (19200baud)
;
;Dirk Duesterberg duesterb@unixserv.rz.fh-hannover.de
;                 http://linux.rz.fh-hannover.de/~duesterb


	DEVICE PIC16C84,HS_OSC,WDT_OFF,PROTECT_OFF

	


ACLK	=	RA.0
ADAT	=	RA.1

TXD	=	RA.2


count0	=	0Ch
count1	=	0Dh

Akeydat	=	0Eh
serbuf	=	0fh

	mov	!RA,#11111011b		;pin 2 is output (TXD)

	mov	!RB,#0			;PortB is output

	jmp	Reset



rawkeys	mov	w,Akeydat
	and	w,#7Fh			;clr bit 7 (make/break or pressed/unpressed)
	jmp	pc+w


; characters, numbers and spezial keys
; $00-$3F

	retw	00h			;00h
	retw	00h			;01h
	retw	00h			;02h
	retw	00h			;03h
	retw	00h			;04h
	retw	00h			;05h
	retw	00h			;06h
	retw	00h			;07h

	retw	00h			;08h
	retw	00h			;09h
	retw	00h			;0Ah
	retw	00h			;0Bh
	retw	00h			;0Ch
	retw	00h			;0Dh
	retw	00h			;0Eh	
	retw	00h			;0Fh



	retw	'q'			;10h
	retw	'w'			;11h
	retw	'e'			;12h
	retw	'r'			;13h
	retw	't'			;14h
	retw	'z'			;15h
	retw	'u'			;16h
	retw	'i'			;17h

	retw	'o'			;18h
	retw	'p'			;19h
	retw	'ü'			;1Ah
	retw	'+'			;1Bh
	retw	00h			;1Ch
	retw	00h			;1Dh
	retw	00h			;1Eh
	retw	00h			;1Fh



	retw	'a'			;20h
	retw	's'			;21h
	retw	'd'			;22h
	retw	'f'			;23h
	retw	'g'			;24h
	retw	'h'			;25h
	retw	'j'			;26h
	retw	'k'			;27h

	retw	'l'			;28h
	retw	'ö'			;29h
	retw	'ä'			;2Ah
	retw	00h			;2Bh
	retw	00h			;2Ch
	retw	00h			;2Dh
	retw	00h			;2Eh
	retw	00h			;2Fh



	retw	00h			;30h
	retw	00h			;31h
	retw	00h			;32h
	retw	00h			;33h
	retw	00h			;34h
	retw	00h			;35h
	retw	00h			;36h
	retw	00h			;37h

	retw	00h			;38h
	retw	00h			;39h
	retw	00h			;3Ah
	retw	00h			;3Bh
	retw	00h			;3Ch
	retw	00h			;3Dh
	retw	00h			;3Eh
	retw	00h			;3Fh

; other spezial keys (space, TAB, Return)
; $40-$4F

	retw	00h			;40h
	retw	00h			;41h
	retw	00h			;42h
	retw	00h			;43h
	retw	00h			;44h
	retw	00h			;45h
	retw	00h			;46h
	retw	00h			;47h

	retw	00h			;48h
	retw	00h			;49h
	retw	00h			;4Ah
	retw	00h			;4Bh
	retw	00h			;4Ch
	retw	00h			;4Dh
	retw	00h			;4Eh
	retw	00h			;4Fh


; Function keys, Help etc.
; $50-$5F

	retw	00h			;50h
	retw	00h			;51h
	retw	00h			;52h
	retw	00h			;53h
	retw	00h			;54h
	retw	00h			;55h
	retw	00h			;56h
	retw	00h			;57h

	retw	00h			;58h
	retw	00h			;59h
	retw	00h			;5Ah
	retw	00h			;5Bh
	retw	00h			;5Ch
	retw	00h			;5Dh
	retw	00h			;5Eh
	retw	00h			;5Fh



; shifting keys like shift, amiga, Alternate and Control
; $60-6F
	
	retw	00h			;60h
	retw	00h			;61h
	retw	00h			;62h
	retw	00h			;63h
	retw	00h			;64h
	retw	00h			;65h
	retw	00h			;66h
	retw	00h			;67h

	retw	00h			;68h
	retw	00h			;69h
	retw	00h			;6Ah
	retw	00h			;6Bh
	retw	00h			;6Ch
	retw	00h			;6Dh
	retw	00h			;6Eh
	retw	00h			;6Fh


;spezial keybord commandos
; $70-$7F

	retw	00h			;70h	
	retw	00h			;71h
	retw	00h			;72h
	retw	00h			;73h
	retw	00h			;74h
	retw	00h			;75h
	retw	00h			;76h
	retw	00h			;77h

	retw	00h			;78h
	retw	00h			;79h=F9h= letzter tasten code war fehlerhaft
	retw	00h			;7Ah=FAh= tastenpuffer im keybord voll
	retw	00h			;7Bh
	retw	00h			;7Ch=FCh= selbsttest der tastatur war fehlerhaft
	retw	00h			;7Dh=FDh= beginn der beim Einschalten gedrueckten Tasten
	retw	00h			;7Eh=FEh= ende der beim Einschalten gedrueckten Tasten
	retw	00h			;7Fh

	






















Reset	clr	Akeydat			;Akeydat is used as character counter

check	csne	Akeydat,#11		;how many characters ?
	jmp	ready
	call	dat
	mov	serbuf,w
	call	sendb			;send letter
	inc	Akeydat
	jmp	check



dat	mov	w,Akeydat		;letter to w routine
	jmp	pc+w
	retw	'mache RESET'







ready	call	sync




rcAdat	mov	count0,#7

:loop	call	wACLK			;wait for Amiga CLK
	rl	Akeydat			;rotate bits into register
	djnz	count0,:loop		;format is x6543210


	rl	Akeydat			;format is 6543210x
	call	wACLK			;wait for Amiga CLK
	rr	Akeydat			;format is 76543210, jippije
	not	Akeydat			;data is inverted

	mov	w,#5
	call	wms			;wait 5 ms

;	mov	serbuf,Akeydat
;	call	sendb			;send raw data


	call	rawkeys
	mov	serbuf,w

	sb	Akeydat.7		;no sending if key up flag is set
	call	sendb			;send the in table found code

	call	AHshake			;all data OK, do the Handshake
	jmp	rcAdat			;receive next byte from keybord











sync	call	wACLK			;wait for clock and do no Acknowledge
	
	mov	w,#250
	call	wms			;wait 250 ms (we want the sync mode!)

	call	wACLK			;wait for Amiga CLK for Handshake

	mov	w,#1
	call	wms			;wait 1 ms

	call	AHshake			;now we do the shake!
	ret


 



wms	mov	count0,w
:loop	mov	count1,#248
:do_it	nop
	djnz	count1,:do_it
	djnz	count0,:loop
	ret






AHshake	mov	!RA,#11111001b		;bit1 = ADAT = output
	clrb	ADAT			;clr Amiga data line
	
	mov	count0,#40		;40 * 3 = 120cycles = 120 µs (min 75µs)
:do_it	djnz	count0,:do_it

	mov	!RA,#11111011b		;bit1 = ADAT = input
	ret






wACLK	snb	ACLK			;wait for neg clock pulse
	jmp	wACLK
	movb	c,Adat			;mov the data to carry bit
wACLK2	sb	ACLK			;wait for pos clock pulse
	jmp	wACLK2
	ret







sendb	call	wbit			;this are stop bits from previous sending
	call	wbit

	setb	TXD			;send startbit
	mov	count0,#8		;8 bits to send
	not	serbuf			;invert serbuf

s_it	call	wbit
	rr	serbuf
	movb	TXD,c
	djnz	count0,s_it		;all bits send ? decrement the bitcounter

	call	wbit
	clrb	TXD			;clear TXD, stopbit, lenght is defined by 
					;next sending
	ret





wbit	mov	count1,#13		;19200 at 4 Mhz
:loop	djnz	count1,:loop
	nop
	ret