reti
reti ; PCINT0
reti
- rjmp keypress ; PCINT1
+ reti ; PCINT1
reti
reti ; PCINT2
reti
; r27 h/
; r28 l\_Y
; r29 h/
-; r30 l\_Z
+; r30 l\_Z (Z) Pointer to next waveform table in rom
; r31 h/
; ------------------------------------------------------------------------------
; ----- Set up button pin and timer for switching waveforms
+ ; Set PORTC5 as input with pullup
+ cbi DDRC, DDC5
+ sbi PORTC, PORTC5
+
+ ; Allow PCINT13 (button) to trigger pin change interrupts
+ ldi r25, (1 << PCINT13)
+ sts PCMSK1, r25
+
+ ; Clear any existing pin interrupts
+ in r25, PCIFR
+ out PCIFR, r25
+
+ ; No need to set PCCSR bits since we won't actually be getting
+ ; interrupted, and PCISR bits will be set regardless
+
+ ; Hold prescaler in reset so timer remains halted until we need it
+ ldi r25, (1 << TSM) | \
+ (1 << PSRSYNC)
+ out GTCCR, r25
+
+ ; Timer 0: CTC mode (reset after compare match)
+ ; Clock source CLK_io / 64
+ ldi r25, (1 << WGM01) | \
+ (0 << WGM00)
+ out TCCR0A, r25
+ ldi r25, (0 << WGM02) | \
+ (3 << CS00)
+ out TCCR0B, r25
+ sbi TIFR0, OCF0A ; Make sure the timer flag is clear
+ ldi r25, 250 ; Count up to 250 (at 16MHz/64 = 250kHz -> 1ms)
+ out OCR0A, r25
+ ldi r25, 0 ; Reset the timer counter
+ out TCNT0, r25
+
+ ; Timer prescaler
+
; ----- Set up the initial waveform
- ; Point Z at the sine table, X at the waveform table
+ ; Point Z at the first waveform in the rom, X at the waveform buffer
ldi XL, LOW(waveform)
ldi XH, HIGH(waveform)
- ldi ZL, LOW(sine*2)
- ldi ZH, HIGH(sine*2)
+ ldi ZL, LOW(2*wavetable_begin)
+ ldi ZH, HIGH(2*wavetable_begin)
; Copy 256 bytes from program memory at Z to data at X
ldi r25, 0x00
brne _load_loop
; Point X at the waveform table (table must be 256-byte aligned)
- ldi r23, 0x00 ; Fractional part
+ ldi r23, 0x00 ; Fractional part
ldi XL, LOW(waveform) ; Integer low part, must be zero
ldi XH, HIGH(waveform) ; Integer high part
- ldi ZL, LOW(sine*2)
- ldi ZH, HIGH(sine*2)
; Initial step size
ldi r16, 0x00 ; Fractional part
- ldi r17, 25 ; Integer part
-
- ; ----- Enable interrupts
+ ldi r17, 0x04 ; Integer part
; --------------------------------------------------------------
loop:
+
+ ; --------------------------------------------------------------
; ----- Output a sample and advance
ld r25, X
add r23, r16 ; Fractional part
adc XL, r17 ; Integer part
out PORTD, r25
+ ; --------------------------------------------------------------
+
+
+ ; --------------------------------------------------------------
; ----- Read the frequency knob and adjust if necessary
; Trigger a single conversion
rjmp _adc_wait
sts ADCSRA, r25 ; Store back to clear the interrupt flag (w1c)
- ; Read value and write to output
+ ; Read value and adjust step size
lds r25, ADCH
+ ; TODO: adjust step size
+ ; --------------------------------------------------------------
+
+
+
+ ; --------------------------------------------------------------
+ ; ----- Poll for button presses and swap waveforms
+
+ ; Test for pin change interrupt flag
+ in r25, PCIFR
+ sbis PCIFR, PCIF1
+ rjmp _button_done
+ ; Button pin status has changed
+
+ ; ----- Advance to next waveform in rom and copy to waveform LUT
+ ; Do this before the switch debouncing so the time spent copying can be
+ ; used as part of the wait time for the switch to settle
+
+ ; Point X at the ram waveform table (Z already points at next in rom)
+ ldi XL, LOW(waveform)
+ ldi XH, HIGH(waveform)
+
+ ; Copy 256 bytes from program memory at Z to data at X
+ ldi r25, 0x00
+_button_load_loop:
+ lpm r24, Z+
+ st X+, r24
+ inc r25
+ brne _button_load_loop
+ cpi ZH, HIGH(2*wavetable_end)
+ brne _button_load_done
+ ldi ZH, HIGH(2*wavetable_begin)
+_button_load_done:
+
+ ; Point X at the waveform table (table must be 256-byte aligned)
+ ldi r23, 0x00 ; Fractional part
+ ldi XL, LOW(waveform) ; Integer low part, must be zero
+ ldi XH, HIGH(waveform) ; Integer high part
+
+ ; ----- Debounce - wait until pin is quiet for some duration
+
+_button_reset_wait:
+ sbi PCIFR, PCIF1 ; Clear pin change flag (w1c)
+ sbi TIFR0, OCF0A ; Clear timer expire flag (w1c)
+ ldi r25, (1 << TSM) | (1 << PSRSYNC)
+ out GTCCR, r25 ; Reset prescaler and hold
+ ldi r25, 0x00 ; Reset timer count value
+ out TCNT0, r25
+ out GTCCR, r25 ; Unhalt the prescaler to run the timer
+_button_busyloop:
+ sbic PCIFR, PCIF1 ; If the pin changed again, reset the clock
+ rjmp _button_reset_wait
+ sbis TIFR0, OCF0A ; If the timer expired, exit the loop
+ rjmp _button_busyloop
+
+ ; ----- Wait for button release
+
+_button_wait_release:
+ sbis PINC, PINC5
+ rjmp _button_wait_release
+
+ ; ----- Debounce again
+
+_button_reset_wait_2:
+ sbi PCIFR, PCIF1 ; Clear pin change flag (w1c)
+ sbi TIFR0, OCF0A ; Clear timer expire flag (w1c)
+ ldi r25, (1 << TSM) | (1 << PSRSYNC)
+ out GTCCR, r25 ; Reset prescaler and hold
+ ldi r25, 0x00 ; Reset timer count value
+ out TCNT0, r25
+ out GTCCR, r25 ; Unhalt the prescaler to run the timer
+_button_busyloop_2:
+ sbic PCIFR, PCIF1 ; If the pin changed again, reset the clock
+ rjmp _button_reset_wait_2
+ sbis TIFR0, OCF0A ; If the timer expired, exit the loop
+ rjmp _button_busyloop_2
+
+_button_done:
+ ; --------------------------------------------------------------
+
rjmp loop
.cseg
-sine:
+; Waveform data must be contiguous
+wavetable_begin:
+; Sine
.db 0x80, 0x83, 0x86, 0x89, 0x8c, 0x8f, 0x92, 0x95
.db 0x98, 0x9c, 0x9f, 0xa2, 0xa5, 0xa8, 0xab, 0xae
.db 0xb0, 0xb3, 0xb6, 0xb9, 0xbc, 0xbf, 0xc1, 0xc4
.db 0x4f, 0x51, 0x54, 0x57, 0x5a, 0x5d, 0x60, 0x63
.db 0x67, 0x6a, 0x6d, 0x70, 0x73, 0x76, 0x79, 0x7c
-square:
+; Square
.db 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
.db 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
.db 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
.db 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
.db 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
-rising_saw:
+; Rising sawtooth
.db 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07
.db 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f
.db 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17
.db 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7
.db 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
-falling_saw:
+; Falling sawtooth
.db 0xff, 0xfe, 0xfd, 0xfc, 0xfb, 0xfa, 0xf9, 0xf8
.db 0xf7, 0xf6, 0xf5, 0xf4, 0xf3, 0xf2, 0xf1, 0xf0
.db 0xef, 0xee, 0xed, 0xec, 0xeb, 0xea, 0xe9, 0xe8
.db 0x0f, 0x0e, 0x0d, 0x0c, 0x0b, 0x0a, 0x09, 0x08
.db 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01, 0x00
-triangle:
+; Triangle
.db 0x00, 0x02, 0x04, 0x06, 0x08, 0x0a, 0x0c, 0x0e
.db 0x10, 0x12, 0x14, 0x16, 0x18, 0x1a, 0x1c, 0x1e
.db 0x20, 0x22, 0x24, 0x26, 0x28, 0x2a, 0x2c, 0x2e
.db 0x1f, 0x1d, 0x1b, 0x19, 0x17, 0x15, 0x13, 0x11
.db 0x0f, 0x0d, 0x0b, 0x09, 0x07, 0x05, 0x03, 0x01
-white_noise: ; Contains all values 0-255, randomized
+; White noise, contains all values 0-255, randomized
.db 0x7a, 0x1b, 0x50, 0xac, 0xa6, 0xf7, 0xf1, 0x82
.db 0x6d, 0xfc, 0x24, 0x5d, 0x6e, 0xe9, 0xd6, 0x74
.db 0x08, 0x8e, 0x28, 0xf6, 0x13, 0x22, 0xd3, 0xb1
.db 0x20, 0x8d, 0x53, 0xa8, 0x19, 0x4c, 0x6f, 0x86
.db 0xce, 0x92, 0x06, 0xe7, 0x7e, 0xb8, 0x5a, 0x3d
.db 0xb5, 0x85, 0x44, 0x16, 0xb7, 0xcc, 0x41, 0xbd
+wavetable_end:
projects / atmega / siggen.git / commitdiff