# HG changeset patch
# User ethanzonca@CL-SEC241-08.cedarville.edu
# Date 2012-10-29 20:38:23
# Node ID c273f460216732be9e34f199c047ef1733e24242
# Parent  db6685a2165ed9a34c47d3b80fb68fbe3d504de1

AFSK is now properly transmitting the first bit of each byte requested to be sent (or so I think...)

diff --git a/master/master/lib/afsk.c b/master/master/lib/afsk.c
--- a/master/master/lib/afsk.c
+++ b/master/master/lib/afsk.c
@@ -20,11 +20,13 @@
 #define F_CPU 11059200
 
 #include <stdint.h>
+#include <stdbool.h>
 #include <avr/io.h>
 #include <avr/interrupt.h> 
 #include <util/delay.h>
 #include <avr/pgmspace.h>
 
+
 PROGMEM extern const uint8_t afsk_sine_table[512] = {
   127, 129, 130, 132, 133, 135, 136, 138, 139, 141, 143, 144, 146, 147, 149, 150, 152, 153, 155, 156, 158, 
   159, 161, 163, 164, 166, 167, 168, 170, 171, 173, 174, 176, 177, 179, 180, 182, 183, 184, 186, 187, 188, 
@@ -90,46 +92,128 @@ void afsk_setup() {
 	DDRD = 0xff;
 	PORTD = 0xff;
 	
+	// todo: init radio, maybe in main
+	
 	sei();
 }
 
+	
+
 void afsk_test() {	
-	afsk_timer_start();
-	_delay_ms(3);
-	phasedelta = 1800;
-	_delay_ms(3);
-	phasedelta = 3300;
-	_delay_ms(3);
-	phasedelta = 1800;
-	_delay_ms(3);
-	phasedelta = 3300;
-	_delay_ms(3);
-	phasedelta = 1800;
-	_delay_ms(3);
-	phasedelta = 3300;
-	_delay_ms(3);
-	phasedelta = 1800;
-	_delay_ms(3);
-	phasedelta = 3300;
-	_delay_ms(3);
-	phasedelta = 1800;
-	_delay_ms(3);
-	phasedelta = 3300;
-	_delay_ms(3);
-	phasedelta = 1800;
-	_delay_ms(3);
-	phasedelta = 3300;
-	afsk_timer_stop();
-	_delay_ms(400);
+	uint8_t flap[32] = "somethingawesomesomethingawesome";
+	afsk_send(flap, 32);
+	afsk_start();
+	while(afsk_busy());
+	_delay_ms(500);
 }
 
 
+
+
+// constants
+#define MODEM_CLOCK_RATE F_CPU
+#define PLAYBACK_RATE MODEM_CLOCK_RATE / 256  // Fast PWM
+
+#define BAUD_RATE 1200
+//#define SAMPLES_PER_BAUD PLAYBACK_RATE / BAUD_RATE // = 36
+#define SAMPLES_PER_BAUD 36
+
+
 // phase offset of 1800 gives ~1900 Hz
 // phase offset of 3300 gives ~2200 Hz
-ISR(TIMER2_OVF_vect) {
-	phase = (phase + phasedelta);
-	OCR2B = afsk_read_sample((phase >> 7) & (TABLE_SIZE - 1));
-	return;
+#define PHASE_DELTA_1200 1800
+#define PHASE_DELTA_2200 2200
+
+// Module globals
+volatile unsigned char current_byte;
+volatile unsigned char current_sample_in_baud;    // 1 bit = SAMPLES_PER_BAUD samples
+volatile bool go = false;                 
+
+volatile unsigned int packet_pos;                 // Next bit to be sent out
+
+
+volatile unsigned int afsk_packet_size = 10;
+volatile const uint8_t *afsk_packet;
+
+
+void afsk_send(const uint8_t *buffer, int len)
+{
+	afsk_packet_size = len;
+	afsk_packet = buffer;
+}
+
+int afsk_busy()
+{
+	return go;
+}
+
+void afsk_start()
+{
+	phasedelta = PHASE_DELTA_1200;
+	phase = 0;
+	packet_pos = 0;
+	current_sample_in_baud = 0;
+	go = true;
+
+	// Key the radio
+	afsk_ptt_on();
+
+	// Start transmission
+	afsk_timer_start();
+}
+
+
+
+afsk_ptt_off() {
+	
+}
+
+afsk_ptt_on() {
+	
+}
+
+
+ISR(TIMER2_OVF_vect) 
+{
+	if (go) {
+
+		// If done sending packet
+		if (packet_pos == afsk_packet_size) {
+			go = false;         // End of transmission
+			afsk_timer_stop();  // Disable modem
+			afsk_ptt_off();    // Release PTT
+			return; // done
+		}
+
+		// If sent SAMPLES_PER_BAUD already, go to the next bit
+		if (current_sample_in_baud == 0) {    // Load up next bit
+			if ((packet_pos & 7) == 0) {          // Load up next byte
+				current_byte = afsk_packet[packet_pos >> 3];
+			}				
+			else {
+				current_byte = current_byte / 2;  // ">>1" forces int conversion
+			}			
+			if ((current_byte & 1) == 0) {
+				// Toggle tone (1200 <> 2200)
+				phasedelta ^= (PHASE_DELTA_1200 ^ PHASE_DELTA_2200);
+			}
+		}
+	
+		phase += phasedelta;
+		uint8_t s = afsk_read_sample((phase >> 7) & (TABLE_SIZE - 1));
+		afsk_output_sample(s);
+
+		if(++current_sample_in_baud == SAMPLES_PER_BAUD) {
+			// sounds fun when this is commented out... but why??!?!
+			//current_sample_in_baud = 0;
+			packet_pos++;
+		}
+		
+	}
+}	
+
+void afsk_output_sample(uint8_t s) {
+	OCR2B = s;
 }
 
 void afsk_timer_start()
@@ -144,7 +228,8 @@ void afsk_timer_start()
 
 void afsk_timer_stop()
 {
-	// Output 0v (after DC coupling)
+	// Resting duty cycle
+	// Output 0v (could be 255/2, which is 0v after coupling... doesn't really matter)
 	OCR2B = 0x00;
 
 	// Disable playback interrupt
diff --git a/master/master/lib/afsk.h b/master/master/lib/afsk.h
--- a/master/master/lib/afsk.h
+++ b/master/master/lib/afsk.h
@@ -11,7 +11,7 @@
 
 void afsk_setup();
 void afsk_test();
-void afsk_timer_start();
-void afsk_timer_stop();
+void afsk_start();
+void afsk_stop();
 
 #endif /* AFSK_H_ */
\ No newline at end of file