add measurement, stolen from tea thermometer

measure.c

@@ -0,0 +1,84 @@
+/*
+ * adc.cpp
+ *
+ *  Created on: 03.10.2014
+ *      Author: wn
+ */
+
+#include <msp430g2553.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <float.h>
+
+#include "measure.h"
+#include "PontCoopScheduler.h"
+#include "pattern.h"
+
+
+const float R_REF = 3000.0;
+const uint16_t N_MAX = 1023;
+const float PT1000_R0 = 1000.0;
+const float PT1000_Coeff = 3.85e-3;
+
+
+const uint32_t MEASURE_CYCLE = 20;
+const uint32_t MEASURE_FETCH_RESULT_DELAY = 5;
+const uint8_t AVERAGING_CYCLES = 50;
+
+
+
+void measureInit() {
+  ADC10CTL0 = SREF1 | ADC10SHT_3 | ADC10SR | REFOUT | REFON | REF2_5V | ADC10ON;
+  ADC10CTL1 = INCH_3;
+  ADC10AE0 = BIT3;
+}
+
+void measureCollectAndProcessConversion();
+
+void measureStartConversion(void *handleArg) {
+  ADC10CTL0 |= ENC | ADC10SC;
+  schAdd(measureCollectAndProcessConversion, NULL, MEASURE_FETCH_RESULT_DELAY, 0);
+}
+
+void measureCollectAndProcessConversion() {
+  static uint32_t averagingSum = 0;
+  static uint8_t averagingCnt = 0;
+
+  uint16_t n = 0xffff;
+  if ((ADC10CTL0 & ADC10IFG) != 0) {
+    n = ADC10MEM;
+    ADC10CTL0 &= ~(ADC10IFG | ENC);
+  }
+
+  if (n != 0xffff) {
+    averagingSum += n;
+    averagingCnt++;
+  }
+
+  if (averagingCnt == AVERAGING_CYCLES)  {
+    uint32_t nAvg = averagingSum / averagingCnt;
+
+    // process adcValue
+    // store result in variable temperature
+    float r = 0.0;
+    if (nAvg == 0) {
+      r = 0.0;
+    } else if (nAvg == N_MAX) {
+      r = FLT_MAX;
+    } else {
+      r = R_REF / ((((float)N_MAX) / ((float)nAvg)) - 1.0);
+    }
+    float t = (r / PT1000_R0 - 1) / PT1000_Coeff;
+
+    uint8_t temperature = (t < 0) ? 0 : ((uint8_t)t);
+
+    // do something with the temperature
+    patternSetTemperature(temperature);
+
+    averagingCnt = 0;
+    averagingSum = 0;
+  }
+}
+
+