Revision 0:118dcae93623, committed 2015-04-14

Comitter:

vk5653

Date:

Tue Apr 14 13:36:36 2015 +0000

Commit message:

basic color sensor using a cds photosensor and a shiftbrite led, based on the project at http://www.instructables.com/id/Using-an-RGB-LED-to-Detect-Colours/?ALLSTEPS

Changed in this revision

diff -r 000000000000 -r 118dcae93623 main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Apr 14 13:36:36 2015 +0000
@@ -0,0 +1,161 @@
+#include "mbed.h"
+//ShiftBrite Demo
+DigitalOut latch(p15);
+DigitalOut enable(p16);
+AnalogIn aout(p20);
+//Cycles through different colors on RGB LED
+SPI spi(p11, p12, p13);
+
+Serial pc(USBTX, USBRX); // tx, rx
+
+void RGB_LED(int red, int green, int blue);
+void checkBalance();
+void setBalance();
+void checkColor();
+void scanning(int step, int on);
+void getReading(int times);
+void printColor();
+
+//global variables
+    // boolean to know if the balance has been set
+    bool balanceSet = false;
+
+    //floats to hold colour arrays
+    float colorArray[] = {0,0,0};
+    float whiteArray[] = {0,0,0};
+    float blackArray[] = {0,0,0};
+
+    //place holder for average
+    int avgRead = 0;
+
+
+//Use SPI hardware to write color values to LED driver chip
+void RGB_LED(int red, int green, int blue) {
+    unsigned int low_color=0;
+    unsigned int high_color=0;
+    high_color=(blue<<4)|((red&0x3C0)>>6);
+    low_color=(((red&0x3F)<<10)|(green));
+    spi.write(high_color);
+    spi.write(low_color);
+    latch=1;
+    latch=0;
+}
+
+
+void checkBalance(){
+  //check if the balance has been set, if not, set it
+  if(balanceSet == false){
+    setBalance();
+  }
+}
+
+
+void setBalance(){
+  //set white balance
+   wait(5);                              //delay for five seconds, this gives us time to get a white sample in front of our sensor
+  //scan the white sample.
+  //go through each light, get a reading, set the base reading for each colour red, green, and blue to the white array
+  for(int i = 0; i<=2; i++){
+     scanning(i,1);
+     wait(0.1);
+     getReading(1);          //number is the number of scans to take for average, this whole function is redundant, one reading works just as well.
+     whiteArray[i] = avgRead;
+     scanning(i,0);
+     wait(0.1);
+  }
+  //done scanning white, now it will pulse blue to tell you that it is time for the black (or grey) sample.
+   //set black balance
+    wait(5);              //wait for five seconds so we can position our black sample 
+  //go ahead and scan, sets the colour values for red, green, and blue when exposed to black
+  for(int i = 0;i<=2;i++){
+     scanning(i,1);
+     wait(0.1);
+     getReading(1);
+     blackArray[i] = avgRead;
+     scanning(i,0);
+     wait(0.1);
+  }
+   //set boolean value so we know that balance is set
+  balanceSet = true;
+  //delay another 5 seconds to allow the human to catch up to what is going on
+  wait(5);
+}
+
+
+void scanning(int step, int on){
+    int mark = 0;
+    if(on == 1){
+        mark = 50;
+    }
+    else {
+        mark = 0;
+    }
+        
+    if (step == 0){
+        RGB_LED(mark,0,0);
+    }
+    else if (step == 1){
+        RGB_LED(0,mark,0);
+    }
+    else {
+        RGB_LED(0,0,mark);  
+    }
+}
+
+
+
+void checkColor(){
+    for(int i = 0;i<=2;i++){
+     scanning(i,1);  //turn the LED, red, green or blue depending which iteration
+     wait(0.1);                      //delay to allow CdS to stabalize, they are slow
+     getReading(5);                  //take a reading however many times
+     colorArray[i] = avgRead;        //set the current colour in the array to the average reading
+     float greyDiff = whiteArray[i] - blackArray[i];                    //the highest possible return minus the lowest returns the area for values in between
+     colorArray[i] = (colorArray[i] - blackArray[i])/(greyDiff)*255; //the reading returned minus the lowest value divided by the possible range multiplied by 255 will give us a value roughly between 0-255 representing the value for the current reflectivity(for the colour it is exposed to) of what is being scanned
+     scanning(i,0);   //turn off the current LED
+     wait(0.1);
+  }
+}
+
+
+void getReading(int times){
+  int reading;
+  int tally=0;
+  //take the reading however many times was requested and add them up
+    for(int i = 0;i < times;i++){
+        reading = aout.read();
+        tally = reading + tally;
+        wait(0.01);
+    }
+  //calculate the average and set it
+  avgRead = (tally)/times;
+}
+
+
+//prints the colour in the colour array, in the next step, we will send this to processing to see how good the sensor works.
+void printColor(){
+    pc.printf("R = ");
+    pc.printf("%d", colorArray[0]);
+    pc.printf("G = ");
+    pc.printf("%d", colorArray[1]);
+    pc.printf("B = ");
+    pc.printf("%d", colorArray[2]);
+}
+
+
+
+int main() {   
+    spi.format(16,0);
+    spi.frequency(500000);
+    enable=0;
+    latch=0;
+    
+    wait(5);  
+    while(1){
+        checkBalance();
+        checkColor();
+        printColor();
+    }
+    
+
+}

diff -r 000000000000 -r 118dcae93623 mbed.bld
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Tue Apr 14 13:36:36 2015 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/487b796308b0
\ No newline at end of file