/* SCP1000 Barometric Pressure Sensor Display Shows the output of a Barometric Pressure Sensor on a Uses the SPI library. For details on the sensor, see: http://www.sparkfun.com/commerce/product_info.php?products_id=8161 http://www.vti.fi/en/support/obsolete_products/pressure_sensors/ This sketch adapted from Nathan Seidle's SCP1000 example for PIC: http://www.sparkfun.com/datasheets/Sensors/SCP1000-Testing.zip Circuit: SCP1000 sensor attached to pins 6, 7, 10 - 13: DRDY: pin 6 CSB: pin 7 MOSI: pin 11 MISO: pin 12 SCK: pin 13 created 31 July 2010 by Tom Igoe */ // the sensor communicates using SPI, so include the library: #include //Sensor's memory register addresses: const int PRESSURE = 0x1F; //3 most significant bits of pressure const int PRESSURE_LSB = 0x20; //16 least significant bits of pressure const int TEMPERATURE = 0x21; //16 bit temperature reading // pins used for the connection with the sensor // the other you need are controlled by the SPI library): const int dataReadyPin = 6; const int chipSelectPin = 7; void setup() { Serial.begin(9600); // start the SPI library: SPI.begin(); // initalize the data ready and chip select pins: pinMode(dataReadyPin, INPUT); pinMode(chipSelectPin, OUTPUT); //Configure SCP1000 for low noise configuration: writeRegister(0x02, 0x2D); writeRegister(0x01, 0x03); writeRegister(0x03, 0x02); // give the sensor time to set up: delay(100); } void loop() { //Select High Resolution Mode writeRegister(0x03, 0x0A); // don't do anything until the data ready pin is high: if (digitalRead(dataReadyPin) == HIGH) { //Read the temperature data int tempData = readRegister(0x21, 2); // convert the temperature to celsius and display it: float realTemp = (float)tempData / 20.0; Serial.print("Temp[C]="); Serial.print(realTemp); //Read the pressure data highest 3 bits: byte pressure_data_high = readRegister(0x1F, 1); pressure_data_high &= 0b00000111; //you only needs bits 2 to 0 //Read the pressure data lower 16 bits: unsigned int pressure_data_low = readRegister(0x20, 2); //combine the two parts into one 19-bit number: long pressure = ((pressure_data_high << 16) | pressure_data_low)/4; // display the temperature: Serial.println("\tPressure [Pa]=" + String(pressure)); } } //Sends a write command to SCP1000 void writeRegister(byte registerName, byte registerValue) { // SCP1000 expects the reguster name in the upper 6 bits // of the byte: registerName <<= 2; // command goes in the lower two bits: registerName |= 0b00000010; //Write command // take the chip select low to select the device: digitalWrite(chipSelectPin, LOW); SPI.transfer(registerName); //Send register location SPI.transfer(registerValue); //Send value to record into register // take the chip select high to de-select: digitalWrite(chipSelectPin, HIGH); //Select SPI device } //Read register from the SCP1000: unsigned int readRegister(byte registerName, int numBytes) { byte inByte = 0; // incoming from the SPI read unsigned int result = 0; // result to return // SCP1000 expects the reguster name in the upper 6 bits // of the byte: registerName <<= 2; // command goes in the lower two bits: registerName &= 0b11111100; //Read command // take the chip select low to select the device: digitalWrite(chipSelectPin, LOW); // send the device the register you want to read: int command = SPI.transfer(registerName); // send a value of 0 to read the forst byte returned: inByte = SPI.transfer(0x00); // if there's more than one byte returned, // shift the first byte then get the second byte: switch(numBytes) { case 1: result = inByte; break; case 2: result = inByte << 8; inByte = SPI.transfer(0x00); result = result |inByte; break; } // take the chip select high to de-select: digitalWrite(chipSelectPin, HIGH); // return the result: return(result); }