battery test

battery-probe/battery-probe.h

@@ -0,0 +1,40 @@
+
+#ifndef BATTERY_NUM_SAMPLES
+	// number of analog samples to take per reading
+	// do not exceed 255 without changing "sample_count" type
+	// "sum" may need to be changed to long type if number of samples exceeds roughly 60
+	// (sum might be 1023* BATTERY_NUM_SAMPLES)
+	// /!\ must be > 0
+	#define BATTERY_NUM_SAMPLES 10
+#endif
+
+#ifndef BATTERY_TEST_PIN
+	// battery pin
+	#define BATTERY_TEST_PIN A2
+#endif
+
+#ifndef BATTERY_CALIBRATED_VCC
+	// calibrated vcc
+	// /!\ must be > 0
+	#define BATTERY_CALIBRATED_VCC 5.0
+#endif
+
+#ifndef BATTERY_SAMPLES_DELAY
+	// delay between two samples
+	#define BATTERY_SAMPLES_DELAY 10
+#endif
+
+// reads BATTERY_NUM_SAMPLES samples on pin BATTERY_TEST_PIN separated
+// by BATTERY_SAMPLES_DELAY ms and computes the mean voltage as a float and returns it.
+float readBatteryVoltage() {
+	unsigned int total = 0; // total of samples taken
+	// take a number of analog samples and add them up
+    for (unsigned char i = 0; i < BATTERY_NUM_SAMPLES; i++) {
+        total += analogRead(BATTERY_TEST_PIN);
+        delay(BATTERY_SAMPLES_DELAY);
+    }
+    // calculate the voltage
+    // use 5.0 for a 5.0V ADC reference voltage
+    // 5.015V is the calibrated reference voltage
+    float voltage = ((float)total / (float)BATTERY_NUM_SAMPLES * BATTERY_CALIBRATED_VCC) / 1024.0;
+}