Diff: main.cpp

Revision:

0:a8fcc4098c24

Child:

1:e59c75779477

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Jun 23 18:40:14 2015 +0000
@@ -0,0 +1,99 @@
+
+
+#include "HIH_4010.h"
+#include "mbed.h"
+
+
+Serial pc(USBTX, USBRX);
+ 
+AnalogIn ain_UseA(p15);
+AnalogIn ain_UseB(p16);
+AnalogIn ain_UseC(p17);
+AnalogIn ain_UseD(p18);
+AnalogIn ain_UseE(p19);
+DigitalOut myled(LED1);
+
+
+/*
+
+Constructor
+dataPin: the IO pin connected to the sensor's data pin (pin 15)
+supplyVoltage: the voltage supplying the humidity sensor (pins 1,3 - typ. 5.0)
+referenceVoltage: motor controller's reference voltage 
+*/
+
+HIH4010::HIH4010(float dataPin, float supplyVoltage, float referenceVoltage){
+
+pin = dataPin;
+vSupply = supplyVoltage;
+vRef = referenceVoltage;
+
+/*
+Relative Humidity is calculated using the following equations taken from the datasheet:
+(1) Vout = (VSupply)(0.00636(sensorRH) + 0.1515)
+(2) sensorRH = (Vout - zeroOffset) / slope
+
+Solving (1) for sensorRH: 
+sensorRH = (Vout - (0.1515)VSupply) / (0.00636)VSupply
+
+Equate result with (2):
+zeroOffset = (0.1515)VSupply
+slope = (0.00636)VSupply
+*/ 
+
+slope = 0.00636 * vSupply;
+zeroOffset = 0.1515 * vSupply; 
+
+}
+
+
+/*
+Convert sensor reading into relative humidity using equation (2)
+*/ 
+
+float HIH4010::getSensorRH() {
+return ((vout() - zeroOffset) / slope);
+
+}
+
+/*
+Get temperature-compensated relative humity. From data sheet: 
+trueRH = sensorRH / (1.0546 - 0.00216T)
+*/
+
+float HIH4010::getTrueRH(float temperature) { 
+return getSensorRH() / (1.0546 - (0.00216 * temperature)); 
+
+}
+
+/*
+Get sensor output voltage.
+Assumes 12-bit (2^16 = 4096) A/D resolution.
+*/
+
+float HIH4010::vout() {
+return (float)(ain_UseA.read_u16()) * 3.3 / 65536;
+
+}
+
+ 
+int main()
+{
+    float ad[5];
+    float vdiv = (3.3 / 65536); //3.3 is the reference voltage (AnalogIn measures from 0V to 3.3V) and 4096 is the highest number that can be represented by a 12 bit unsigned
+    while( 1 ){
+        ad[0] = (float)ain_UseA.read_u16() * vdiv;  //returns 12 bit value representing the current input voltage normalized 
+        ad[1] = (float)ain_UseB.read_u16() * vdiv;
+        ad[2] = (float)ain_UseC.read_u16() * vdiv;
+        ad[3] = (float)ain_UseD.read_u16() * vdiv;
+        ad[4] = (float)ain_UseE.read_u16() * vdiv;
+        pc.printf("%5.3f,%5.3f,%5.3f,%5.3f,%5.3f\r\n ", ad[0],ad[1],ad[2],ad[3],ad[4]);
+        HIH4010 humidity(ad[0], 3.3, 3.3);
+        //pc.printf("%5.3f\r\n" , humidity.vout());
+        pc.printf("%5.3f\r\n", humidity.getSensorRH());
+    myled = 1;
+    wait(2.0);
+    myled = 0;
+    wait(2.0);
+    }
+}