init m05e01

module05/ex01/adc.c

@@ -0,0 +1,25 @@
+#include "header.h"
+
+// Table 14-6. Port C Pins Alternate Functions
+// - PC0 -> ADC0 (ADC Input Channel 0)
+//       -> PCINT8 (Pin Change Interrupt 8)
+//
+// 24.2 : The ADC generates a 10-bit result which is presented in the ADC Data Registers, ADCH and ADCL
+//
+// START A CONVERSTION in single conversion mode :
+// - disabling the Power Reduction ADC bit, PRADC
+// - writing a logical one to the ADC Start Conversion bit, ADSC
+
+void adc_init(uint8_t prescaler_value) {
+    ADMUX = (1 << REFS0);								// Table 24-3 : set voltage reference, AVCC with external capacitor at AREF pin
+    ADCSRA = (1 << ADEN); 								// 24.9.2 : enable ADC
+    ADCSRA |= ADC_PRESCALE_SET(prescaler_value);		// Table 24-5 : prescaler ADC
+}
+
+uint16_t adc_read(uint8_t channel) {
+	CLEAR(PRR, PRADC);									// 24.3 : ensure power reduction is disabled for ADC, (10.11.3 : PRR – Power Reduction Register)
+    ADMUX = (ADMUX & 0b11110000) | (channel & 0b1111);	// Table 24-4 : Select ADC channel, (Table 14-6 : alternate function for RV1 on PC0 -> ADC0)
+    ADCSRA |= (1 << ADSC);								// 24.9.2 : Start conversion, ADSC: ADC Start Conversion
+    while (ADCSRA & (1 << ADSC));						// Wait for completion
+    return ADC;
+}