; ; i0.test.bridge.asm ; bridge bytes between I0 and RS-232 ; Modified by Ken Avery and then Tom Owens on 12/17/05 for MAS863 ; ; Neil Gershenfeld CBA MIT 9/8/05 ; (c) Massachusetts Institute of Technology 2005 ; Permission granted for experimental and personal use; ; license for commercial use available from MIT ; .include "tn13def.inc" ;.equ rxpin = PB0; receive pin .equ txpin = PB4; transmit pin .equ clickin = PB3 ; I0 input pin .equ buttonbit = 2; pushbutton bit .equ buttonpin = PB2; pushbutton pin .equ ledpin2 = PB1 ; I0 output pin .def txbyte = R24 .def bitcount = R16; bit counter .def byte = R17; tx/rx byte .def clickdelay2 = R18; click spacing .def tripledelay = R19; triple click spacing .def count = R20; loop counter .def doublecount = R21; double loop count .def temp = R22; temporary storage .def temp1 = R23; temporary storage .cseg .org 0 rjmp reset ; ; getchar ; input a serial byte following first transition ; ;getchar: ; ldi bitcount, 9 ; 8 data bit + 1 stop bit ; rcall bitdelay ; 0.5 bit delay ; getcharloop: ; rcall bitdelay ; 1 bit delay ; rcall bitdelay ; ; clc ; clear carry ; sbis PINB, rxpin ; if RX pin high skip ; sec ; otherwise set carry ;dec bitcount ; breq getcharend ; return if all bytes read ; ror byte ; otherwise shift bit into receive byte ; rjmp getcharloop ; get next bit ; getcharend: ; ret ; ; putchar ; output a serial byte ; putchar: .equ sb = 1 ; number of stop bits ldi bitcount, 9+sb; 1+8+sb com byte ; invert everything sec ; set start bit putchar0: brcc putchar1 ; if carry set sbi PORTB, txpin ; send a '0' rjmp putchar2 ; else putchar1: cbi PORTB, txpin ; send a '1' nop ; even out timing putchar2: rcall bitdelay ; one bit delay rcall bitdelay lsr byte ; get next bit dec bitcount ; if not all bits sent brne putchar0 ; send next bit ret ; ; getclick ; input an I0 byte following first click ; getclick: clr clickdelay2 nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop sbi ACSR, ACI ; reset comparator ; ; find click delay from arrival of second start click ; start2: inc clickdelay2 breq getclicktimeout ; time-out if count overflows sbis ACSR, ACI rjmp start2 ;mov byte, clickdelay2 ;rcall putchar mov tripledelay, clickdelay2 add tripledelay, clickdelay2 add tripledelay, clickdelay2 ; ; decode data clicks ; clr byte ldi bitcount, 8 bitloop: ; ; time arrival of next click ; clr count nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop ;nop ;nop ;nop ;nop ;nop ;nop ;nop ;nop sbi ACSR, ACI ; reset comparator bitclickloop: inc count breq getclicktimeout ; time-out if count overflows sbis ACSR, ACI rjmp bitclickloop ; ; determine bit delay ; mov doublecount, count add doublecount, count cp doublecount, tripledelay brsh zero ; ; one bit ; sec ; set carry ror byte ; shift in carry ; ; even out timing with click delay ; mov count, clickdelay2 onedelay: nop ; time for breq nop ; time for sbis nop nop dec count brne onedelay dec bitcount brne bitloop ; output if byte received rjmp getclickend zero: ; ; zero bit ; clc ; clear carry ror byte ; shift in carry dec bitcount brne bitloop ; output if byte received getclickend: ret getclicktimeout: mov byte, clickdelay2 ret ; ; ; packet_delay ; delay between packets ; packet_delay: ldi temp, 255 packet_delayloop: ldi temp1, 255 packet_delayloop1: dec temp1 brne packet_delayloop1 dec temp brne packet_delayloop ret ; putclick ; output an I0 byte ; putclick: ldi bitcount, 8 sec; set start bit ; ; send start clicks ; cbi PORTB, ledpin2 sbi PORTB, ledpin2 rcall clickdelay cbi PORTB, ledpin2 rcall clickdelay sbi PORTB, ledpin2 rcall clickdelay cbi PORTB, ledpin2 cbi PORTB, ledpin2 rcall clickdelay ; ; send data clicks ; putclick0: lsr txbyte; get next bit brcc putclick1; if carry set, send a 1 click cbi PORTB, ledpin2 sbi PORTB, ledpin2 rcall clickdelay cbi PORTB, ledpin2 rcall clickdelay cbi PORTB, ledpin2 rcall clickdelay cbi PORTB, ledpin2 cbi PORTB, ledpin2 rcall clickdelay rjmp putclick2; otherwise ... putclick1: cbi PORTB, ledpin2; ... send a 0 click cbi PORTB, ledpin2 rcall clickdelay cbi PORTB, ledpin2 rcall clickdelay sbi PORTB, ledpin2 rcall clickdelay cbi PORTB, ledpin2 cbi PORTB, ledpin2 rcall clickdelay putclick2: dec bitcount; if not all bits sent brne putclick0; send next bit ; ; send stop clicks ; cbi PORTB, ledpin2 sbi PORTB, ledpin2 rcall clickdelay cbi PORTB, ledpin2 rcall clickdelay sbi PORTB, ledpin2 rcall clickdelay cbi PORTB, ledpin2 cbi PORTB, ledpin2 rcall clickdelay ; ; return ; ret ; ; bitdelay ; serial bit delay ; .equ b = 17 bitdelay: ldi temp, b bitdelayloop: dec temp brne bitdelayloop ret ; ; clickdelay ; delay between clicks ; clickdelay: ldi temp, 200 clickdelayloop: ;ldi temp1, 200 ;clickdelayloop2: ; dec temp1 ;brne clickdelayloop2 dec temp brne clickdelayloop ret ; pulsedelay: ldi temp, 3 pulsedelayloop: dec temp brne pulsedelayloop ret ; ; ; main program ; reset: ldi temp, low(RAMEND) ; set stack pointer to top of RAM out SPL, temp ; cbi PORTB, txpin; init comm pin for output sbi DDRB, txpin sbi PORTB, buttonpin ; init pushbutton pin for input with pull-up cbi DDRB, buttonpin ; sbi PORTB, ledpin2 ; init irled control pin for output sbi DDRB, ledpin2 cbi ACSR, ACIS1 ; setup comparator to output on state change cbi ACSR, ACIS0 ; sbi ADCSRB, ACME ; setup comparator to use ADC multiplexer cbi ADCSRA, ADEN ; sbi ADMUX, MUX1 ; set channel to ADC3 sbi ADMUX, MUX0 ; loop: ; ; wait for a click or a bit ; sbi ACSR, ACI ; reset comparator waitloop: sbic ACSR, ACI ; check for click rjmp click sbic PINB, buttonbit ; check for button rjmp waitloop button: ; ; send the string and blink the LED ; cbi PORTB, ledpin2 ;sbi PORTB, ledpin2 ;ldi txbyte, END ; SLIP start ;rcall putclick ;rcall chardelay ;ldi txbyte, 254 rcall packet_delay sbi PORTB, ledpin2 ;cbi PORTB, ledpin2 rjmp loop click: ; ; blink the LED ; rcall getclick ;cbi PORTB, ledpin2 ;ldi byte, 4 rcall putchar ;rcall packet_delay ;sbi PORTB, ledpin2 rjmp loop