main.cpp

00001 /* Discrete RGB color sensor
00002  *
00003  * - uses single-channel light-dependent resistor (via ADC)
00004  *   and a RGB LED.
00005  * -  compensates background light
00006  *
00007  * Copyright (c) 2014 ARM Limited
00008  *
00009  * Licensed under the Apache License, Version 2.0 (the "License");
00010  * you may not use this file except in compliance with the License.
00011  * You may obtain a copy of the License at
00012  *
00013  *     http://www.apache.org/licenses/LICENSE-2.0
00014  *
00015  * Unless required by applicable law or agreed to in writing, software
00016  * distributed under the License is distributed on an "AS IS" BASIS,
00017  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00018  * See the License for the specific language governing permissions and
00019  * limitations under the License.
00020  */
00021 
00022 #include <mbed.h>
00023 #include "rgb_sensor_buffer.h"
00024 
00025 #define DEBUG
00026 
00027 #define RGB_TRESHOLD 220
00028 #define COUNT(x) (sizeof(x)/sizeof(x[0]))
00029 #define RGB_VALUES 512
00030 
00031 /* serial console */
00032 static TRGB g_buffer[RGB_VALUES];
00033 static int g_median[RGB_VALUES];
00034 static Serial console(USBTX, USBRX);
00035 
00036 #ifdef DEBUG
00037 static void rgb_print(const TRGB &color)
00038 {
00039     int i;
00040 
00041     console.printf("\t[");
00042     for(i=0; i<COUNT(color.data); i++)
00043         console.printf("%s%4i", i?",":"", color.data[i] / RGB_OVERSAMPLING);
00044     console.printf("]");
00045 }
00046 #endif/*DEBUG*/
00047 
00048 static int median_compare(const void* a, const void *b)
00049 {
00050         return *((int*)a) - *((int*)b);
00051 }
00052 
00053 static bool median(TRGB &color, int count)
00054 {
00055     int channel, i;
00056 
00057     if(count<=0)
00058         return false;
00059 
00060     /* sort all three RGB channels to get median */
00061     for(channel=0; channel<3; channel++)
00062     {
00063         for(i=0; i<count; i++)
00064             g_median[i] = g_buffer[i].data[channel];
00065 
00066         qsort(&g_median, count, sizeof(g_median[0]), &median_compare);
00067 
00068         color.data[channel] = g_median[count/2];
00069     }
00070 
00071     return true;
00072 }
00073 
00074 
00075 int main() {
00076     int res;
00077     double magnitude;
00078     TRGB color;
00079 
00080     console.baud(115200);
00081 
00082     /* R,G,B pins and ADC for light dependent resistor */
00083     RGB_SensorBuffer rgb(p23,p24,p25,p20);
00084 
00085     /* needed for time measurement */
00086     Timer timer;
00087 
00088     while(1) {
00089 
00090         /* start four channel RGB conversion */
00091         timer.reset();
00092         timer.start();
00093 
00094         res = rgb.trigger(g_buffer, COUNT(g_buffer), RGB_TRESHOLD);       
00095 
00096         /* stop time measurement */
00097         timer.stop();
00098     
00099         if(res<=0)
00100         {
00101             console.printf("// failed to capture RGB values (%i)\r\n", res);
00102             while(1);
00103         }
00104 
00105         /* calculate RGB median */
00106         median(color, res);
00107         /* print normalized median */
00108         magnitude = sqrt(
00109             ( (double)color.ch.red   * color.ch.red   )+
00110             ( (double)color.ch.green * color.ch.green )+
00111             ( (double)color.ch.blue  * color.ch.blue  )
00112         );
00113         console.printf("\t[%1.4f,%1.4f,%1.4f,%5i], // %i values in %ims (%i/s)\n\r",
00114             color.ch.red   / magnitude,
00115             color.ch.green / magnitude,
00116             color.ch.blue  / magnitude,
00117             (int)((magnitude / RGB_OVERSAMPLING)+0.5),
00118             res,
00119             timer.read_ms(),
00120             (res*1000UL)/timer.read_ms()
00121         );
00122 
00123 #ifdef DEBUG
00124         int i;
00125         console.printf("\r\nvar test = [\r\n",
00126             res,
00127             timer.read_ms(),
00128             (res*1000UL)/timer.read_ms());
00129 
00130         for(i=0; i<res; i++)
00131         {
00132             rgb_print(g_buffer[i]);
00133             console.printf(i<(res-1) ? ",\r\n":"];\r\n\r\n");
00134         }
00135 #endif/*DEBUG*/
00136 
00137     }
00138 }