File content as of revision 3:93078a6f3bad:

//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
    }
}