main.cpp

00001 #include "mbed.h"
00002 #include "math.h"
00003 
00004 Serial pc (USBTX, USBRX);
00005 Serial xbee (PTE0, PTE1);
00006 
00007 const int ARRAY_LENGTH    = 50;
00008 float temperature_celsius, temperature_voltage, light_voltage, raw_pir_reading, noise_voltage, noise_maximum, noise_average, noise_total, noise_variance, noise_sd, presence_percentage, num_consecutive_runs;
00009 char publishString[40];
00010 float noise_array[ARRAY_LENGTH];
00011 int pir_array[ARRAY_LENGTH];
00012 
00013 //bool DEBUG_MODE = false;
00014 
00015 AnalogIn light_ain(A0);
00016 AnalogIn temp_ain(A1);
00017 AnalogIn pir_ain(A2);
00018 AnalogIn noise_ain(A3);
00019 
00020 void publish_measurements() {
00021     temperature_voltage = temp_ain.read_u16();
00022     // Convert DAC reading to millivolts
00023     temperature_voltage = (temperature_voltage * 3.3 * 1000) / 4095;
00024     // Convert millivolts to Celsius using datasheet equation
00025     temperature_celsius = (2103 - temperature_voltage) / 10.9;
00026     //if(DEBUG_MODE) {
00027         //Serial.println("Temperature (Celsius): " + String(temperature_celsius));
00028     //}
00029 
00030     light_voltage = light_ain.read_u16();
00031 
00032     sprintf(publishString,"%.1f, %.1f, %.1f, %.1f, %.1f", temperature_celsius, light_voltage, noise_maximum, noise_average, noise_variance);
00033     xbee.printf(publishString);
00034     pc.printf("publish");
00035     pc.printf(publishString);
00036     sprintf(publishString, "%.1f, %.1f", presence_percentage, num_consecutive_runs);
00037     xbee.printf(publishString);
00038 }
00039 
00040 
00041 void measure_pir_and_noise() {
00042     noise_voltage = 0;
00043 
00044     for (int i = 0; i < ARRAY_LENGTH; i++) {
00045         raw_pir_reading = pir_ain.read_u16();
00046         noise_voltage = noise_ain.read_u16();
00047         noise_array[i] = noise_voltage;
00048         if (raw_pir_reading > 3000) {
00049             pir_array[i] = 1;
00050         } else {
00051             pir_array[i] = 0;
00052         }
00053         //if (DEBUG_MODE) {
00054             //Serial.println("PIR: " + String(raw_pir_reading));
00055             //Serial.println("Noise: " + String(noise_voltage));
00056         //}
00057         wait(0.1);
00058     }
00059 }
00060 
00061 
00062 void noise_analysis() {
00063     float residuals[ARRAY_LENGTH];
00064     noise_maximum = 0;
00065     noise_average = 0;
00066     noise_variance = 0;
00067     noise_total = 0;
00068 
00069     for (int i = 0; i < ARRAY_LENGTH; i++) {
00070         if (noise_array[i] > noise_maximum) noise_maximum = noise_array[i];
00071         noise_total += noise_array[i];
00072     }
00073     noise_average = noise_total / (ARRAY_LENGTH * 1.0);
00074 
00075     for (int i = 0; i < ARRAY_LENGTH; i++) {
00076         residuals[i] = noise_array[i] - noise_average;
00077         noise_variance += residuals[i] * residuals[i];
00078     }
00079     noise_variance = noise_variance / (ARRAY_LENGTH * 1.0);
00080 }
00081 
00082 
00083 void pir_analysis() {
00084     int counts_over_1s = 0;
00085     int longest_consecutive_run = 0;
00086     int curr_num_consecutive = 0;
00087 
00088     counts_over_1s = pir_array[0] == 1 ? 1 : 0;
00089     for (int i = 1; i < ARRAY_LENGTH; i++) {
00090         if (pir_array[i] == 1) {
00091             ++counts_over_1s;
00092         }
00093         if (pir_array[i] == 1 && pir_array[i-1] == 1) {
00094             ++curr_num_consecutive;
00095         } else {
00096             if (curr_num_consecutive > longest_consecutive_run) {
00097                 longest_consecutive_run = curr_num_consecutive;
00098                 curr_num_consecutive = 0;
00099             }
00100         }
00101     }
00102 
00103     presence_percentage = 100 * counts_over_1s * 1.0 / ARRAY_LENGTH;
00104     num_consecutive_runs = longest_consecutive_run;
00105 }
00106 
00107 
00108 int main() {
00109     while (1) {        
00110   measure_pir_and_noise();
00111   noise_analysis();
00112   pir_analysis();
00113   publish_measurements();
00114   
00115 }
00116 }