Diff: Main.cpp

Revision:

3:93078a6f3bad

Child:

4:67b457cac0ec

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Main.cpp	Wed Dec 11 11:41:14 2019 +0000
@@ -0,0 +1,38 @@
+//SGP30 Air Quality sensor
+//Laurence Wilkins CU Coventry University
+
+#include "mbed.h"
+#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
+
+const int SGP30I2CAddress7 = 0x58;                  // 7-bit I2C address
+const int SGP30I2CAddress8 = 0x58 << 1;             // 8-bit I2C address, shifted (0xA2)
+
+int main()
+{
+    char cmd[2];                                    //two byte array for 16 bit address/command
+    char data[6];                                   // six byte array for data
+    lcd.cls();                                      //clear LCD screen
+
+    cmd[0] = 0x20;                                  //address 0X0203 initialises sensor
+    cmd[1] = 0x03;
+    i2c.write(SGP30I2CAddress8, cmd, 2);            //2=two bytes of data
+
+    while(1) {
+        wait(1.0f);                                 //wait 1 second btween 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
+    }
+}