--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/blackbox/driver/adc.c Mon Nov 14 20:31:32 2011 +0100
@@ -0,0 +1,79 @@
+#include "adc.h"
+#include <avr/io.h>
+#include <string.h>
+#include <stdint.h>
+
+
+// Functions to access the internal ADC
+
+// internal ADC reference configuration
+static uint8_t adcReference=(1<<REFS0); // = VCC 5V
+
+// get a sample from ADC chip.
+// chanell must be in range 0-7.
+uint16_t getADC(int channel) {
+ if (channel == 0)
+ adcReference = ((1<<REFS1) | (1<<REFS0)); // switch to 2.56V (~2x
+ //adcReference = (1<<REFS1); // switch to 1.1v (~4.5x) - not on ATMEGA16
+ else
+ adcReference = (1<<REFS0); // switch to 5v (1x)
+ ADMUX = adcReference + channel;
+ // start one sample
+ ADCSRA |= (1<<ADSC);
+ // wait for the result
+ loop_until_bit_is_clear(ADCSRA, ADSC);
+ return ADC;
+}
+
+// initialize the ADC
+void initADC() {
+ ADCSRA |= (1<<ADEN) | (1<<ADPS2) | (1<<ADPS1) | (1<<ADPS0);
+}
+
+// select reference
+// value can be "VCC", "1.1V or "2.56V"
+// returns 1 on success
+uint8_t setAREF(char* name) {
+ if (strcmp(name,"VCC")==0)
+ adcReference=(1<<REFS0);
+ else if (strcmp(name,"1.1V")==0)
+ adcReference=(1<<REFS1);
+ else if (strcmp(name,"2.56V")==0)
+ adcReference=((1<<REFS1) | (1<<REFS0));
+ else if (strcmp(name,"EXT")==0)
+ adcReference=0;
+ else
+ return 0;
+ // Perform one sample to initialize the ADC on the new reference
+ ADMUX = adcReference;
+ ADCSRA |= (1<<ADSC);
+ loop_until_bit_is_clear(ADCSRA, ADSC);
+ (ADC);
+ return 1;
+}
+
+#ifdef EXT_AREF
+// get current current voltage
+// This assumes that VCC is 5.0 Volt.
+float getAREF(void) {
+ uint8_t aref=ADMUX & ((1<<REFS1) | (1<<REFS0));
+ if (aref == 0)
+ return EXT_AREF/1024;
+ else if (aref == (1<<REFS0))
+ return 5.00/1024;
+ else if (aref == (1<<REFS1))
+ return 1.10/1024;
+ else
+ return 2.56/1024;
+}
+#endif
+
+
+uint16_t getADC_smooth(uint8_t channel, uint8_t samples) {
+ uint16_t result = 0;
+ unsigned char i;
+ for (i=0; i<samples; i++) {
+ result += getADC(channel);
+ }
+ return (result / samples);
+};