; efe.charge.asm
; (c) Neil Gershenfeld CBA MIT 8/29/04
;
; definitions
;
.include "tn13def.inc"

.equ ledpin = PB3; LED pin
.equ rxpin = PB4; receive pin

.def temp = R16; temporary storage
.def temp1 = R17	; temporary storage
.def bitcnt = R18 ; temporary storage
.def txbyte = R19 ; data byte
.def c_count = R20 ; low byte step up
.def high_up = R21 ; high byte step up
.def comphigh = R22 ; LED highstate
.def txbytec = R23 ;  state compare byte
.def count = R24; delay count.def temp = R16
.def sample_count = R25 ; sample counter
.def sample_delay = R26 ; delay between samples
.def delay_count = R27 ; delay loop counter
.def cycle_count = R28 ; cycle counter
.def byte = R29 ; note counter
;.def note_lo = R30 ; reserved for OCR0B
.def note_hi = R31 ; note high byte


; start of code
;
.cseg
.org 0

rjmp reset ; jump to reset routine

;
; waveform
; first byte = number of samples
;
wave:
   .db 99,191,195,199,203,207,211,215,218,222
   .db 225,229,232,235,238,240,243,245,247,249
   .db 250,252,253,254,254,254,254,254,254,253
   .db 252,251,250,248,246,244,242,239,236,233
   .db 230,227,224,220,216,213,209,205,201,197
   .db 193,189,185,181,177,173,169,166,162,158
   .db 155,152,149,146,143,140,138,136,134,132
   .db 131,130,129,128,128,128,128,128,128,129
   .db 130,132,133,135,137,139,142,144,147,150
   .db 153,157,160,164,167,171,175,179,183,187

;
; getchar
; assumes no line driver (doesn't invert bits)
;

getchar:
   ldi bitcnt,9 ; 8 data bit + 1 stop bit
   getchar1:
      sbis PINB, rxpin ; wait for start bit
      rjmp getchar1
   rcall bit_delay ; 0.5 bit delay
   getchar2:
      rcall bit_delay ; 1 bit delay
      rcall bit_delay ;
      clc ; clear carry
      sbis PINB, rxpin ; if RX pin high skip
         sec ; otherwise set carry
      dec bitcnt
      breq getchar3 ; return if all bits read
      ror byte ; otherwise shift bit into receive byte
      rjmp getchar2 ; go get next bit
   getchar3:
      ret
;
; bit delay
;
.equ b = 17 ; 9600 bps
bit_delay:
   ldi temp, b
   bitloop:
      dec temp
      brne bitloop
   ret

;
; routine to wait for sample to settle
;
.equ delay = 10
settle:
   ldi temp1, delay
   sloop1:
      ldi temp, delay
      sloop0:
         dec temp
         brne sloop0
      dec temp1
      brne sloop1
   ret
;
; LED delay
;
;.equ count = 100
print_delay:
   mov temp1, count
   delay_loop1:
      mov temp, count
      delay_loop:
         dec temp
         brne delay_loop	
      dec temp1
      brne delay_loop1
   ret


; long_print_delay
; delay between printed lines
;
;.equ delay2 = 100
;long_print_delay:
   ;ldi temp2, delay2
   ;charloop2:
      ;ldi temp1, delay2
      ;charloop1:
         ;ldi temp, delay2
         ;charloop0:
            ;dec temp
            ;brne charloop0
         ;dec temp1
         ;brne charloop1
      ;dec temp2
      ;brne charloop2
   ;ret

; main program
;
reset:	   
   ldi temp, low(RAMEND) ; maximum RC clock
   out SPL, temp
   sbi PORTB, ledpin; init LED pin
   sbi DDRB, ledpin
   ;
   ; init A/D
   ;
   cbi ADMUX, REFS0 ; "
   cbi ADMUX, ADLAR ; right-adjust result
   sbi ADCSRA, ADEN ; enable A/D
   cbi ADCSRA, ADATE ; set for single-shot
   cbi ADCSRA, ADIE ; disable A/D interrupt
   cbi ADCSRA, ADPS2 ; set prescaler
   cbi ADCSRA, ADPS1 ; "
   cbi ADCSRA, ADPS0 ; "
   sbi PORTB, PB0 ; output on PB0
   sbi DDRB, PB0 
   cbi ADMUX, MUX1 ; "
   sbi ADMUX, MUX0 ; "
   ;
   ; init pwm
   ;
   ldi temp, (1<<CLKPCE)
   ldi temp1, ((0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0))
   out CLKPR, temp ; write CLKPCE to change clock prescaler
   ;out CLKPR, temp1 ; set clock to 9.6MHz/1
   ldi temp, ((1 << COM0B0) | (1 << COM0B1) | (1 << WGM01) | (1 << WGM00))
   out TCCR0A, temp ; set OC0B on compare match and set fast PWM mode, 0xFF TOP
   ldi temp, (1 << CS00)
   out TCCR0B, temp ; set timer 0 prescalar to 1
   sbi DDRB, PB1 ; enable OC0B output pin
   ldi temp, (1 << TOIE0) ; enable timer 0 overflow interrupt
   out TIMSK0, temp

   ; infinite main loop
   ;
   loop:
      ;
      clr txbyte
	  clr txbytec
	  ;
      ; settle sample and start upward step response
      ;
      cbi PORTB, PB0
      rcall settle
      sbi PORTB, PB0
      ;
      ; wait for delay
      ;
      nop
      ;
      ; read response
      ;
      sbi ADCSRA, ADSC ; start conversion
      adloop1up:
         sbic ADCSRA, ADSC ; loop until complete
         rjmp adloop1up
      ;
      ; save conversion
      ;
      in txbyte, ADCL ; save low byte
      in high_up, ADCH ; save high byte
      ;
      ; start downward step response
      ;
      cbi PORTB, PB0
      ;
      ; wait for delay
      ;
      nop
      ;
      ; read response
      ;
      sbi ADCSRA, ADSC ; start conversion
      adloop1down:
         sbic ADCSRA, ADSC ; loop until complete
         rjmp adloop1down
      ;
      ; send downward conversion
      ;
      in txbyte, ADCL ; send low byte
	  clr txbyte
      in txbyte,ADCH ; send high byte
	  clr txbyte
      ;
      ; send upward conversion
      ;
      mov txbytec, txbyte
      mov txbytec, high_up
	  ldi comphigh,0
	  ldi cycle_count, 10
	  ldi sample_delay, 20
	  cp comphigh, txbytec
	  breq LED_loop
      ldi R30, 255
	  out OCR0B, R30
      rjmp loop
  
LED_loop:
      cbi PORTB, ledpin
      mov c_count, cycle_count
      cycle_loop:
            ;
            ; read number of samples
            ;
            ldi zl, low(wave*2)
            ldi zh, high(wave*2)
            lpm
            mov sample_count, R0
	    ;
	    ; loop over samples
	    ;
            sample_loop:
               adiw zl, 1 ; move to next sample
               lpm ; read sample
               out OCR0B, R0 ; update PWM
               mov delay_count, sample_delay
               sample_delay_loop:
                  dec delay_count
                  brne sample_delay_loop
               dec sample_count ; decrease sample count
               brne sample_loop ; get next sample, ...
			rcall getchar
	        ldi comphigh,4
            cp byte, comphigh
	        breq delay_loop3
            dec c_count
            brne cycle_loop
            sbi PORTB, ledpin
			rjmp loop

delay_loop3:
      ldi count, 200
	  ldi R30, 255
	  out OCR0B, R30
      rcall print_delay
      rcall print_delay
      rjmp LED_loop