Laurence Wilkins / Mbed 2 deprecated DHT11-HelloWorld

DHT11 example f

Dependencies:   mbed C12832 I2CLCD TextLCD

Main.cpp@5:973401999337, 2019-12-12 (annotated)

Committer:
LaurenceW
Date:
Thu Dec 12 09:30:45 2019 +0000
Revision:
5:973401999337
Parent:
4:67b457cac0ec 
SGP30 Hello World

Who changed what in which revision?

UserRevisionLine numberNew contents of line
LaurenceW 3:93078a6f3bad 1 //SGP30 Air Quality sensor
LaurenceW 3:93078a6f3bad 2 //Laurence Wilkins CU Coventry University
LaurenceW 3:93078a6f3bad 3
LaurenceW 3:93078a6f3bad 4 #include "mbed.h"
LaurenceW 3:93078a6f3bad 5 #include "C12832.h"
LaurenceW 3:93078a6f3bad 6
LaurenceW 3:93078a6f3bad 7 C12832 lcd(p5, p7, p6, p8, p11); // set up instance of LCd screen
LaurenceW 5:973401999337 8 I2C i2c(p28, p27); //I2c built into mbed.h, define standard pins (data, clock)
LaurenceW 5:973401999337 9 DigitalOut CO2Alarm (LED1);
LaurenceW 5:973401999337 10 DigitalOut VOCAlarm (LED2);
LaurenceW 3:93078a6f3bad 11
LaurenceW 5:973401999337 12 const int SGP30I2CAddress8 = 0x58 << 1; // 8-bit I2C address=0x58, shifted left (0xA2)
LaurenceW 5:973401999337 13
LaurenceW 3:93078a6f3bad 14
LaurenceW 3:93078a6f3bad 15 int main()
LaurenceW 3:93078a6f3bad 16 {
LaurenceW 3:93078a6f3bad 17 char cmd[2]; //two byte array for 16 bit address/command
LaurenceW 3:93078a6f3bad 18 char data[6]; // six byte array for data
LaurenceW 3:93078a6f3bad 19 lcd.cls(); //clear LCD screen
LaurenceW 3:93078a6f3bad 20
LaurenceW 3:93078a6f3bad 21 cmd[0] = 0x20; //address 0X0203 initialises sensor
LaurenceW 3:93078a6f3bad 22 cmd[1] = 0x03;
LaurenceW 5:973401999337 23 wait_ms(1); //give SGP30 time to stabilise after power up
LaurenceW 3:93078a6f3bad 24 i2c.write(SGP30I2CAddress8, cmd, 2); //2=two bytes of data
LaurenceW 5:973401999337 25 lcd.printf("Initiailising...");
LaurenceW 3:93078a6f3bad 26
LaurenceW 3:93078a6f3bad 27 while(1) {
LaurenceW 4:67b457cac0ec 28 wait(1.0f); //wait 1 second between reads
LaurenceW 3:93078a6f3bad 29 lcd.locate(0,0); //LCD cursor to top left
LaurenceW 3:93078a6f3bad 30 cmd[0] = 0x20;
LaurenceW 3:93078a6f3bad 31 cmd[1] = 0x08; //command 0X0208 reads six bits of air quality
LaurenceW 5:973401999337 32 if(i2c.write(SGP30I2CAddress8, cmd, 2)==false) {// check if I2C data was returned
LaurenceW 5:973401999337 33 wait_ms(15); // MUST awiat 15mS after read request before read
LaurenceW 5:973401999337 34 i2c.read(SGP30I2CAddress8, data, 6); //read six bytes from sensor into data array
LaurenceW 5:973401999337 35 int CO2 = ((data[0]*256) + data[1]); //first two bits are CO2. Ignore checksums
LaurenceW 5:973401999337 36 int VOC = ((data[3]*256) + data[4]); //bits 3 & 4 are VOC. Ignore checksums
LaurenceW 5:973401999337 37
LaurenceW 5:973401999337 38 if (CO2>1000) { //check if thresholds reached, sound alarm
LaurenceW 5:973401999337 39 CO2Alarm=true;
LaurenceW 5:973401999337 40 } else {
LaurenceW 5:973401999337 41 CO2Alarm=false;
LaurenceW 5:973401999337 42 }
LaurenceW 5:973401999337 43 if (VOC>500) {
LaurenceW 5:973401999337 44 VOCAlarm=true;
LaurenceW 5:973401999337 45 } else {
LaurenceW 5:973401999337 46 VOCAlarm=false;
LaurenceW 5:973401999337 47 }
LaurenceW 5:973401999337 48
LaurenceW 5:973401999337 49 lcd.printf("SGP30 Gas Sensor "); //pretty heading
LaurenceW 5:973401999337 50 lcd.locate(0,10);
LaurenceW 5:973401999337 51 lcd.printf("CO2:%d ppm VOC:%d ppb ",CO2,VOC);
LaurenceW 5:973401999337 52 lcd.locate(0,20);
LaurenceW 5:973401999337 53 lcd.printf("Data: %02hhX %02hhX %02hhX %02hhX %02hhX %02hhX", data[0], data[1], data[2], data[3], data[4], data[5]);
LaurenceW 5:973401999337 54 //line above is for debugging only; it displays the six bytes read from sensor
LaurenceW 5:973401999337 55 } else { //if no I2C response
LaurenceW 5:973401999337 56 lcd.cls();
LaurenceW 5:973401999337 57 lcd.printf("Sensor offline - check connection.");
LaurenceW 5:973401999337 58 }
LaurenceW 3:93078a6f3bad 59 }
LaurenceW 3:93078a6f3bad 60 }