Implemented variable VREF for DAC and ADC

Makefile

@@ -28,7 +28,7 @@ FORMAT = ihex
 
 # List C source files here. (C dependencies are automatically generated.)
 #SRC = $(TARGET).c
-SRC = main.c hardware/Serial.c hardware/AFSK.c util/CRC-CCIT.c protocol/AX25.c protocol/KISS.c
+SRC = main.c hardware/Serial.c hardware/AFSK.c hardware/VREF.c util/CRC-CCIT.c protocol/AX25.c protocol/KISS.c
 
 # If there is more than one source file, append them above, or modify and
 # uncomment the following:

device.h

@@ -8,9 +8,13 @@
 #define F_CPU 20000000UL
 #define FREQUENCY_CORRECTION 0
 
-// ADC settings
+// Voltage references
+// TODO: Determine best defaults
+#define CONFIG_ADC_REF 128
+#define CONFIG_DAC_REF 255
+
+// Demodulator settings
 #define OPEN_SQUELCH true
-#define ADC_REFERENCE REF_3V3
 
 // Serial settings
 #define BAUD 115200

hardware/AFSK.c

@@ -22,7 +22,6 @@ int afsk_putchar(char c, FILE *stream);
 
 // ADC and clock setup
 void AFSK_hw_init(void) {
-
     // Set Timer1 to normal operation
     TCCR1A = 0;
 

hardware/AFSK.h

@@ -46,7 +46,7 @@ inline static uint8_t sinSample(uint16_t i) {
 #define CONFIG_AFSK_TRAILER_LEN 25UL
 #define BIT_STUFF_LEN 5
 
-#define BITRATE    2400
+#define BITRATE 1200
 
 #if BITRATE == 1200
     #define CONFIG_SAMPLERATE 9600UL

hardware/VREF.c

@@ -0,0 +1,30 @@
+#include "VREF.h"
+
+uint8_t adcReference = CONFIG_ADC_REF;
+uint8_t dacReference = CONFIG_DAC_REF;
+
+void VREF_init(void) {
+    //DDRD |= _BV(7);
+    DDRD = 0xFF;
+
+    TCCR2A = _BV(WGM20) |
+             _BV(WGM21) |
+             _BV(COM2A1)|
+             _BV(COM2B1);   
+
+    TCCR2B = _BV(CS20);
+
+    OCR2A = adcReference;
+    OCR2B = dacReference;
+}
+
+
+void vref_setADC(uint8_t value) {
+	adcReference = value;
+	OCR2A = adcReference;
+}
+
+void vref_setDAC(uint8_t value) {
+	dacReference = value;
+	OCR2B = dacReference;
+}

hardware/VREF.h

@@ -0,0 +1,11 @@
+#ifndef VREF_H
+#define VREF_H
+
+#include <avr/io.h>
+#include "device.h"
+
+void VREF_init(void);
+void vref_setADC(uint8_t value);
+void vref_setDAC(uint8_t value);
+
+#endif

main.c

@@ -2,6 +2,7 @@
 #include <avr/io.h>
 
 #include "device.h"
+#include "hardware/VREF.h"
 #include "hardware/AFSK.h"
 #include "hardware/Serial.h"
 #include "protocol/AX25.h"
@@ -25,6 +26,7 @@ void init(void) {
     stdout = &serial.uart0;
     stdin  = &serial.uart0;
 
+    VREF_init();
     AFSK_init(&modem);
     ax25_init(&AX25, &modem, &modem.fd, ax25_callback);