Revision 1:10700868060f, committed 2013-10-16

Comitter:

yihui

Date:

Wed Oct 16 05:39:07 2013 +0000

Parent:

0:71564ae5e242

Commit message:

changing color with temperature

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/USBDevice.lib	Wed Oct 16 05:39:07 2013 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/USBDevice/#d495202c90f4

--- a/main.cpp	Tue Oct 15 09:42:36 2013 +0000
+++ b/main.cpp	Wed Oct 16 05:39:07 2013 +0000
@@ -1,19 +1,73 @@
 #include "mbed.h"
 #include "ChainableLED.h"
 
-DigitalOut led(LED4);
+//#define DEBUG
+
+#ifdef DEBUG
+
+#include "USBSerial.h"
+#define LOG(args...)        pc.printf(args)
+USBSerial pc;
+
+#else
+
+#define LOG(args...)
+
+#endif  // DEBUG
+
+
 // ChainableLED(clk, data, number_of_leds)
 ChainableLED color_led(P1_14, P1_13, 1);
+AnalogIn thermistor(P0_12);
+
+float get_temperature()
+{
+    unsigned int a, beta = 3975;
+    float temperature, resistance;
+    
+    a = thermistor.read_u16();
+    
+    /* Calculate the resistance of the thermistor from analog votage read. */
+    resistance = (float) 10000.0 * ((65536.0 / a) - 1);
+    
+    /* Convert the resistance to temperature using Steinhart's Hart equation */
+    temperature=(1/((log(resistance/10000.0)/beta) + (1.0/298.15)))-273.15; 
+    
+    return temperature;
+}
+
+int temperature2color(float t)
+{
+    float low  = 26;
+    float high = 30;
+    int   min = 0;
+    int   max = 255;
+    int   color;
+    
+    if (t < low) {
+        color = min;
+    } else if (t > high) {
+        color = max;
+    } else {
+        color = min + (max - min) * ((t - min) / (max - min));
+    }
+    
+    return color;
+}
+    
 
 int main() {
-    uint8_t value = 0;
-    
+  
     while(1) {
-        value += 10;
+        float t = get_temperature();
+        uint8_t color = temperature2color(t);
+        
+        LOG("Temperature: %f\r\n", t);
+        LOG("Color: %d\r\n", color);
+        
         // ChainableLED.setColorRGB(index_of_led, red, green, blue)
-        color_led.setColorRGB(0, value, 0xFF - value, 0);
-        led = !led;
-        wait(0.4);
+        color_led.setColorRGB(0, color, 0xFF - color, 0);
+        wait(0.05);
     }
 }