read values from adc (unfiltered)

sensor/include/adc.h

@@ -19,6 +19,9 @@
 #ifndef __ADC_H__
 #define __ADC_H__
 
+#include <stdint.h>
+
 void adcInit(void);
+uint32_t adcGet(void);
 
 #endif // __ADC_H__

sensor/src/adc.c

@@ -18,9 +18,35 @@
 
 #include <avr/io.h>
 #include <avr/interrupt.h>
+#include <util/atomic.h>
 
 #include "adc.h"
 
+static uint32_t adc_value = 0;
+
 void adcInit(void) {
+    ADMUX = (1 << MUX0); // Vcc reference, ADC1 / PB2 in
+    ADCSRA = (1 << ADEN) | (1 << ADIE) // adc and interrupt enabled
+            | (1 << ADPS2) | (1 << ADPS1) // prescaler 64
+            | (1 << ADSC); // start first conversion
+}
+
+static inline void adcFilter(uint16_t val) {
+    adc_value = val; // TODO
+}
+
+ISR(ADC_vect) {
+    // add this value to our filtered average
+    adcFilter(ADC);
+
+    // start next conversion
+    ADCSRA |= (1 << ADSC);
+}
 
+uint32_t adcGet(void) {
+    uint32_t val;
+    ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+        val = adc_value;
+    }
+    return val;
 }

sensor/src/usb.c

@@ -21,6 +21,7 @@
 #include "usbdrv.h"
 #include "osccal.c" // missing usbdrv include, so include here
 
+#include "adc.h"
 #include "main.h"
 
 #define CUSTOM_RQ_ECHO 0 // send back wValue and wIndex, for testing comms reliability
@@ -52,7 +53,7 @@ usbMsgLen_t usbFunctionSetup(uchar data[8]) {
         }
         return 1;
     } else if (rq->bRequest == CUSTOM_RQ_GET) {
-        uint32_t ldr_value = 23; // TODO
+        uint32_t ldr_value = adcGet();
         dataBuffer[0] = (ldr_value & 0x000000FF) >> 0;
         dataBuffer[1] = (ldr_value & 0x0000FF00) >> 8;
         dataBuffer[2] = (ldr_value & 0x00FF0000) >> 16;