Laurence Wilkins / Mbed 2 deprecated DHT11-HelloWorld

DHT11 example f

Dependencies:   mbed C12832 I2CLCD TextLCD

Main.cpp@3:93078a6f3bad, 2019-12-11 (annotated)

Committer:
LaurenceW
Date:
Wed Dec 11 11:41:14 2019 +0000
Revision:
3:93078a6f3bad
Child:
4:67b457cac0ec
Basic SGP30 gas sensor program to display CO2 and VOC values on embedded LCD. As simple as it gets!

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 3:93078a6f3bad 8 I2C i2c(p28, p27); //I2c build into mbed.h, define pincs
LaurenceW 3:93078a6f3bad 9
LaurenceW 3:93078a6f3bad 10 const int SGP30I2CAddress7 = 0x58; // 7-bit I2C address
LaurenceW 3:93078a6f3bad 11 const int SGP30I2CAddress8 = 0x58 << 1; // 8-bit I2C address, shifted (0xA2)
LaurenceW 3:93078a6f3bad 12
LaurenceW 3:93078a6f3bad 13 int main()
LaurenceW 3:93078a6f3bad 14 {
LaurenceW 3:93078a6f3bad 15 char cmd[2]; //two byte array for 16 bit address/command
LaurenceW 3:93078a6f3bad 16 char data[6]; // six byte array for data
LaurenceW 3:93078a6f3bad 17 lcd.cls(); //clear LCD screen
LaurenceW 3:93078a6f3bad 18
LaurenceW 3:93078a6f3bad 19 cmd[0] = 0x20; //address 0X0203 initialises sensor
LaurenceW 3:93078a6f3bad 20 cmd[1] = 0x03;
LaurenceW 3:93078a6f3bad 21 i2c.write(SGP30I2CAddress8, cmd, 2); //2=two bytes of data
LaurenceW 3:93078a6f3bad 22
LaurenceW 3:93078a6f3bad 23 while(1) {
LaurenceW 3:93078a6f3bad 24 wait(1.0f); //wait 1 second btween reads
LaurenceW 3:93078a6f3bad 25 lcd.locate(0,0); //LCD cursor to top left
LaurenceW 3:93078a6f3bad 26 cmd[0] = 0x20;
LaurenceW 3:93078a6f3bad 27 cmd[1] = 0x08; //command 0X0208 reads six bits of air quality
LaurenceW 3:93078a6f3bad 28 i2c.write(SGP30I2CAddress8, cmd, 2);
LaurenceW 3:93078a6f3bad 29 wait(0.015); // MUST awiat 15mS after read request before read
LaurenceW 3:93078a6f3bad 30 i2c.read(SGP30I2CAddress8, data, 6); //read six bytes from sensor into data array
LaurenceW 3:93078a6f3bad 31 int CO2 = ((data[0]*256) + data[1]); //first two bits are CO2. Ignore checksums
LaurenceW 3:93078a6f3bad 32 int VOC = ((data[3]*256) + data[4]); //bits 3 & 4 are VOC. Ignore checksums
LaurenceW 3:93078a6f3bad 33 lcd.printf("SGP30 Gas Sensor \n\r"); //pretty heading
LaurenceW 3:93078a6f3bad 34 lcd.printf("CO2:%d ppm VOC:%d ppb \n\r",CO2,VOC);
LaurenceW 3:93078a6f3bad 35 lcd.printf("Raw: %02hhX %02hhX %02hhX %02hhX %02hhX %02hhX", data[0], data[1], data[2], data[3], data[4], data[5]);
LaurenceW 3:93078a6f3bad 36 //line above is for debugging only; it displays the six bytes read from sensor
LaurenceW 3:93078a6f3bad 37 }
LaurenceW 3:93078a6f3bad 38 }