Diff: Main.cpp

Revision:

5:973401999337

Parent:

4:67b457cac0ec

Child:

6:5992fbd136ad

--- a/Main.cpp	Wed Dec 11 11:48:52 2019 +0000
+++ b/Main.cpp	Thu Dec 12 09:30:45 2019 +0000
@@ -5,10 +5,12 @@
 #include "C12832.h"
 
 C12832 lcd(p5, p7, p6, p8, p11);                    // set up instance of LCd screen
-I2C i2c(p28, p27);                                  //I2c build into mbed.h, define pincs
+I2C i2c(p28, p27);                                  //I2c built into mbed.h, define standard pins (data, clock)
+DigitalOut CO2Alarm (LED1);
+DigitalOut VOCAlarm (LED2);
 
-const int SGP30I2CAddress7 = 0x58;                  // 7-bit I2C address
-const int SGP30I2CAddress8 = 0x58 << 1;             // 8-bit I2C address, shifted (0xA2)
+const int SGP30I2CAddress8 = 0x58 << 1;             // 8-bit I2C address=0x58, shifted left (0xA2)
+
 
 int main()
 {
@@ -18,21 +20,41 @@
 
     cmd[0] = 0x20;                                  //address 0X0203 initialises sensor
     cmd[1] = 0x03;
+    wait_ms(1);                                     //give SGP30 time to stabilise after power up
     i2c.write(SGP30I2CAddress8, cmd, 2);            //2=two bytes of data
+    lcd.printf("Initiailising...");
 
     while(1) {
         wait(1.0f);                                 //wait 1 second between reads
         lcd.locate(0,0);                            //LCD cursor to top left
         cmd[0] = 0x20;
         cmd[1] = 0x08;                              //command 0X0208 reads six bits of air quality
-        i2c.write(SGP30I2CAddress8, cmd, 2);
-        wait(0.015);                                // MUST awiat 15mS after read request before read
-        i2c.read(SGP30I2CAddress8, data, 6);        //read six bytes from sensor into  data array
-        int CO2 = ((data[0]*256) + data[1]);        //first two bits are CO2. Ignore checksums
-        int VOC = ((data[3]*256) + data[4]);        //bits 3 & 4 are VOC. Ignore checksums
-        lcd.printf("SGP30 Gas Sensor \n\r");        //pretty heading
-        lcd.printf("CO2:%d ppm VOC:%d ppb \n\r",CO2,VOC);
-        lcd.printf("Raw: %02hhX %02hhX %02hhX %02hhX %02hhX %02hhX", data[0], data[1], data[2], data[3], data[4], data[5]);
-        //line above is for debugging only; it displays the six bytes read from sensor
+        if(i2c.write(SGP30I2CAddress8, cmd, 2)==false) {// check if I2C data was returned
+            wait_ms(15);                                // MUST awiat 15mS after read request before read
+            i2c.read(SGP30I2CAddress8, data, 6);        //read six bytes from sensor into  data array
+            int CO2 = ((data[0]*256) + data[1]);        //first two bits are CO2. Ignore checksums
+            int VOC = ((data[3]*256) + data[4]);        //bits 3 & 4 are VOC. Ignore checksums
+
+            if (CO2>1000) {                             //check if thresholds reached, sound alarm
+                CO2Alarm=true;
+            } else {
+                CO2Alarm=false;
+            }
+            if (VOC>500) {
+                VOCAlarm=true;
+            } else {
+                VOCAlarm=false;
+            }
+
+            lcd.printf("SGP30 Gas Sensor    ");        //pretty heading
+            lcd.locate(0,10);
+            lcd.printf("CO2:%d ppm VOC:%d ppb   ",CO2,VOC);
+            lcd.locate(0,20);
+            lcd.printf("Data: %02hhX %02hhX %02hhX %02hhX %02hhX %02hhX", data[0], data[1], data[2], data[3], data[4], data[5]);
+            //line above is for debugging only; it displays the six bytes read from sensor
+        } else {                                        //if no I2C response
+            lcd.cls();
+            lcd.printf("Sensor offline - check connection.");
+        }
     }
 }