DHT11 example f
Dependencies: mbed C12832 I2CLCD TextLCD
Main.cpp
- Committer:
- LaurenceW
- Date:
- 2019-12-12
- Revision:
- 5:973401999337
- Parent:
- 4:67b457cac0ec
File content as of revision 5:973401999337:
//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 built into mbed.h, define standard pins (data, clock) DigitalOut CO2Alarm (LED1); DigitalOut VOCAlarm (LED2); const int SGP30I2CAddress8 = 0x58 << 1; // 8-bit I2C address=0x58, shifted left (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; 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 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."); } } }