Ken Todotani
Sample program to get ambient temperature from MCP9700 sensor
Revision 0:6dde232b3b3b, committed 2010-11-23
- Comitter:
- todotani
- Date:
- Tue Nov 23 00:46:29 2010 +0000
- Commit message:
Changed in this revision
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/LinearTempSensor/LinearTempSensor.cpp Tue Nov 23 00:46:29 2010 +0000
@@ -0,0 +1,92 @@
+/* mbed Linear Temperature Sensor library
+ * Supports Microchip MCP9700/9701, National Semiconductor LM35
+ *
+ * Written by Todotani, Nov 22 2010
+ */
+
+#include "LinearTempSensor.h"
+
+LinearTempSensor::LinearTempSensor(PinName ain, int N, SensorType type):
+ // Initialize private variables using Initialization Lists
+ // _ain(ain) is equivalent to _ain = new AnalogIn(ain)
+ // _sample(N) is equivalent to _sample = N
+ _ain(ain), _samples(N), _type(type) {
+ sampleBuffer = (float *)malloc(sizeof(float) * _samples);
+ sampleCount = 0;
+ index = 0;
+ Vref = 3300;
+ bufferNotFilled = true;
+
+ // Set constants to calculate temperature from sensor value
+ switch (_type) {
+ case LM35:
+ V0 = 0.0f;
+ Tc = 10.0f;
+ break;
+ case MCP9701:
+ V0 = 400.0f;
+ Tc = 19.5f;
+ break;
+ case MCP9700:
+ default:
+ V0 = 500.0f;
+ Tc = 10.0f;
+ }
+
+ for (int i = 0; i < _samples; i++)
+ sampleBuffer[i] = 0.0f;
+}
+
+
+LinearTempSensor::~LinearTempSensor() {
+ free(sampleBuffer);
+}
+
+
+float LinearTempSensor::Sense() {
+ float val;
+
+ val = _ain * Vref;
+ sampleBuffer[index] = val;
+ //printf("Index:%d ", index); // Debug print
+ if ( ++index >= _samples )
+ index = 0;
+
+ if ( bufferNotFilled && (sampleCount == _samples) ) {
+ bufferNotFilled = false;
+ }
+ //printf("flag:%d ", bufferNotFilled); // Debug print
+ sampleCount++;
+
+ return val;
+}
+
+
+float LinearTempSensor::GetAverageTemp() {
+ float sum = 0;
+ int i, numberOfsumples;
+
+ if (sampleCount == 0)
+ return 0;
+
+ if (bufferNotFilled) {
+ // In case number of samples less than buffer lenght
+ for (i = 0; i < sampleCount; i++) {
+ sum += sampleBuffer[i];
+ }
+ numberOfsumples = sampleCount;
+ } else {
+ // In case buffer is filled
+ for (i = 0; i < _samples; i++) {
+ sum += sampleBuffer[i];
+ }
+ numberOfsumples = _samples;
+ }
+
+ return ((sum / numberOfsumples) - V0) / Tc; // Temp = (Vout - V0) / Tc
+}
+
+
+float LinearTempSensor::GetLatestTemp() {
+ return (sampleBuffer[(sampleCount-1)%_samples] - V0) / Tc;
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/LinearTempSensor/LinearTempSensor.h Tue Nov 23 00:46:29 2010 +0000
@@ -0,0 +1,73 @@
+/* mbed Linear Temperature Sensor library
+ * Supports Microchip MCP9700/9701, National Semiconductor LM35
+ *
+ * Written by Todotani, Nov 22 2010
+ */
+
+#ifndef MBED_LINEARTEMPSENSOR_H
+#define MBED_LINEARTEMPSENSOR_H
+
+#include "mbed.h"
+
+/** Linear Temperature Sensor class.
+ * Sample and store sensor acuired value in N (default=10) times and
+ * calculate avarage temperature from sampled data
+ * Supports Microchip MCP9700/9701, National Semiconductor LM35
+ * @author Todotani
+ */
+class LinearTempSensor {
+public:
+ /** Sensor Type Definitions */
+ enum SensorType {
+ MCP9700, /**< Microchip MCP9700 (Default) */
+ MCP9701, /**< Microchip MCP9701 */
+ LM35 /**< National Semiconductor LM35 */
+ };
+
+ /** Create a Temperature Sensor instanse
+ *
+ * @param ain PinName of analog input
+ * @param N Number of samples to calculate average temperature (default = 10)
+ * @param type Sensor type (default = MCP9700)
+ */
+ LinearTempSensor(PinName ain, int N = 10, SensorType type = MCP9700);
+
+ /** Sample (read) sensor data and store to buffer
+ *
+ * @param None
+ * @return Sensor-acuired value (mV)
+ */
+ float Sense();
+
+ /** Calculate average temperature from sample buffer
+ *
+ * @param None
+ * @return Average temperature from N times of sumple (Centigrade)
+ */
+ float GetAverageTemp();
+
+ /** Calculate temperature from the latest sample
+ *
+ * @param None
+ * @return Temperature from the latest sampled data (Centigrade)
+ */
+ float GetLatestTemp();
+
+ ~LinearTempSensor();
+
+private:
+ AnalogIn _ain;
+ int _samples;
+ SensorType _type;
+
+ float *sampleBuffer; // Buffer to store sensor acuired data
+ bool bufferNotFilled; // Flag shows that buffer have not filled
+ uint32_t sampleCount;
+ uint32_t index;
+
+ float V0; // Sensor read value in case 0 degree
+ float Tc; // Tmperature coefficient (temprature inclease) in each degree
+ float Vref; // Reference volgate for ADC
+};
+
+#endif
\ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/TextLCD.lib Tue Nov 23 00:46:29 2010 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/simon/code/TextLCD/#a53b3e2d6f1e
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Tue Nov 23 00:46:29 2010 +0000
@@ -0,0 +1,28 @@
+#include "mbed.h"
+#include "TextLCD.h"
+#include "LinearTempSensor.h"
+
+TextLCD lcd(p24, p26, p27, p28, p29, p30, TextLCD::LCD16x2); // RS, E, DB4, DB5, DB6, DB7
+LinearTempSensor sensor(p20); // With default parameters
+//LinearTempSensor sensor(p20, 5, LinearTempSensor::MCP9700); // With option parameters
+
+int main()
+{
+ float Vout, Tav, To;
+
+ lcd.cls();
+ lcd.printf("TEMP:");
+
+ while(true)
+ {
+ Vout = sensor.Sense(); // Sample data (read sensor)
+ Tav = sensor.GetAverageTemp(); // Calculate average temperature from N samples
+ To = sensor.GetLatestTemp(); // Calculate temperature from the latest sample
+
+ lcd.locate(5, 0);
+ lcd.printf("%4.1f", Tav);
+ printf("Vout:%f Tav:%f To:%f\n\r", Vout, Tav, To); // Debug print
+
+ wait(2.0);
+ }
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Tue Nov 23 00:46:29 2010 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/e2ac27c8e93e