change globals to valatile to prevent crashes. make version for pragramming throuigh Arduino IDE

eagle/sk910-waveshape/firmware/main.c

@@ -18,10 +18,10 @@
 // Globals
 // ------------------------------------------------------------------------------
 
-unsigned int line_idx;
-unsigned char table[256];
-unsigned char table_read_idx;
-unsigned char do_sample_video;
+volatile unsigned int line_idx;
+volatile unsigned char table[256];
+volatile unsigned char table_read_idx;
+volatile unsigned char do_sample_video;
 
 // ==============================================================================
 // Functions

eagle/sk910-waveshape/sk910-firmware/sk910-firmware.ino

@@ -0,0 +1,134 @@
+//---------------------------------------------------------------------------------------------
+//	SK910	Waveshaper										ATMEGA88
+//
+// 	Part of the Synkie Project: www.synkie.net
+//
+// 	© 2017 Michael Egger, Licensed under GNU GPLv3
+//
+//--------------------------------------------------------------------------------------------
+// ==============================================================================
+// includes
+// ------------------------------------------------------------------------------
+// AVR Libc (see http://www.nongnu.org/avr-libc/)
+#include <avr/io.h>			// include I/O definitions (port names, pin names, etc)
+#include <avr/wdt.h>		// include watchdog timer support
+#include <avr/interrupt.h>	// include interrupt support
+
+// ==============================================================================
+// Globals
+// ------------------------------------------------------------------------------
+
+volatile unsigned int line_idx;
+volatile unsigned char table[256];
+volatile unsigned char table_read_idx;
+volatile unsigned char do_sample_video;
+
+// ==============================================================================
+// Functions
+// ------------------------------------------------------------------------------
+
+
+
+// ------------------------------------------------------------------------------
+// Init
+// ------------------------------------------------------------------------------
+void init (void) {
+	
+	DDRD = (1 << PD6); 	// PWM OUt
+	
+	EICRA 	= ( 1 << ISC10 | 1 << ISC01 ); 					// Any logical change on INT1 generates an interrupt request. - odd/even
+																		// The falling edge of INT0 generates an interrupt request.	- pulse
+	EIMSK = ( 1 << INT1 | 1 << INT0);									// enable INT1 and INT0
+	
+	ADCSRA 	= (1 << ADEN | 1 << ADATE | 1 << ADIE);						// Enable ADC , trigger on interrupt 0
+	ADCSRB	= (1 << ADTS1);	
+	ADCSRA |= 1<<ADSC;		// Start Conversion
+
+	// Timer 0 : PWM Output
+	TCCR0A = ( 1 << COM0A1 | 1 << WGM01 | 1  << WGM00); 
+	TCCR0B = ( 1 << CS00);							// CTC Mode, no prescaler @8mhz / 256 -> 31.25khz sampling rate
+	TIMSK0 = ( 1 << TOIE0);
+	
+	// Timer 1 : speed of reading back samples -> output frequency
+	TCCR1A = ( 1 << COM1A0 );						// Toggle OC1A/OC1B on compare match, 
+	TCCR1B = ( 1 << WGM12 | 1 << CS11);				// CTC Mode, prescaler 8
+		//befor: no prescaler @8mhz / 256 -> max 31.25khz sampling rate
+	TIMSK1 = (1 << OCIE1A); 
+
+	wdt_enable(WDTO_30MS);			// enable watchdog timer
+	sei();
+}
+
+// ------------------------------------------------------------------------------
+// 													odd/even - vertical blanking
+// 											on one field sample cv, on other video
+ISR (INT1_vect) {  						
+	line_idx = 0;
+	if (PIND & (1 << PD3)) {			
+		do_sample_video = 1;
+		ADMUX = 0;
+	} else {
+		ADMUX = 1;
+		do_sample_video = 0;
+	}
+}
+
+// ------------------------------------------------------------------------------
+// 														dummy for ADC trigger
+
+ISR (INT0_vect) {}  
+
+// ------------------------------------------------------------------------------
+// 														ADC interrupt
+
+ISR (ADC_vect) {
+	if (do_sample_video) {
+		if (line_idx > 35) {
+			if (line_idx < 292) {
+				table[line_idx - 36] = ((ADCL | ADCH << 8)>>2);
+			}
+		}
+	} else {
+		if (line_idx == 50) {
+			unsigned int cv_input;
+			cv_input = (ADCL | ADCH << 8);
+			cv_input = 1024-cv_input;
+			cv_input += 4;
+			OCR1AL = (unsigned char)cv_input;
+			OCR1AH = (unsigned char)(cv_input >> 8);
+		}
+	}
+	line_idx++;
+}
+
+// ------------------------------------------------------------------------------
+// 														Timer 1 Overflow: output next sample
+
+ISR (TIMER1_COMPA_vect) {
+	table_read_idx++;
+} 
+
+// ------------------------------------------------------------------------------
+// 														Timer 0 Overflow: adjust pwm
+
+ISR (TIMER0_OVF_vect) {
+	OCR0A = table[table_read_idx];
+} 
+
+// ==============================================================================
+// main
+// ------------------------------------------------------------------------------
+
+int main (void) {
+
+	
+	init();
+	unsigned char i;
+	for (i=0;i<254;i++) {table[i]=i;}
+	OCR1AL = 0xdf;
+
+	while(1) {
+		wdt_reset();
+	}
+	return 0;
+}