diff --git a/libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde b/libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde index 1859a5b8a..24df38c63 100644 --- a/libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde +++ b/libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde @@ -1,33 +1,37 @@ -/* - 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 MOSI, MISO, SCK pins are different depending on the - MISO: pin 12 board type. See your board's documentation for details - SCK: pin 13 - created 31 July 2010 - by Tom Igoe - */ +/* + 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 +modified 14 August 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 +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 +cont byte READ = 0b11111100; // SCP1000's read command +const byte WRITE = 0b00000010; // SCP1000's write command // pins used for the connection with the sensor // the other you need are controlled by the SPI library): @@ -35,116 +39,104 @@ const int dataReadyPin = 6; const int chipSelectPin = 7; void setup() { - Serial.begin(9600); + Serial.begin(9600); - // start the SPI library: - SPI.begin(); + // start the SPI library: + SPI.begin(); - // initalize the data ready and chip select pins: - pinMode(dataReadyPin, INPUT); - pinMode(chipSelectPin, OUTPUT); + // 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); + //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); + //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); + // 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); + // 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 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; + //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)); - } + // display the temperature: + Serial.println("\tPressure [Pa]=" + String(pressure)); + } } +//Read from or write to register from the SCP1000: +unsigned int readRegister(byte thisRegister, int bytesToRead ) { + byte inByte = 0; // incoming byte from the SPI + unsigned int result = 0; // result to return + + // SCP1000 expects the register name in the upper 6 bits + // of the byte. So shift the bits left by two bits: + thisRegister = thisRegister << 2; + // now combine the address and the command into one byte + dataToSend = thisRegister & READ; + + // take the chip select low to select the device: + digitalWrite(chipSelectPin, LOW); + // send the device the register you want to read: + SPI.transfer(dataToSend); + // send a value of 0 to read the first byte returned: + result = SPI.transfer(0x00); + // decrement the number of bytes left to read: + bytesToRead--; + // if you still have another byte to read: + if (bytesToRead > 0) { + // shift the first byte left, then get the second byte: + result = result << 8; + inByte = SPI.transfer(0x00); + // combine the byte you just got with the previous one: + result = result | inByte; + // decrement the number of bytes left to read: + bytesToRead--; + } + // take the chip select high to de-select: + digitalWrite(chipSelectPin, HIGH); + // return the result: + return(result); +} + + //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); -} - - - - - - - - +void writeRegister(byte thisRegister, byte thisValue) { + // SCP1000 expects the register address in the upper 6 bits + // of the byte. So shift the bits left by two bits: + thisRegister = thisRegister << 2; + // now combine the register address and the command into one byte: + dataToSend = thisRegister | WRITE; + // take the chip select low to select the device: + digitalWrite(chipSelectPin, LOW); + SPI.transfer(dataToSend); //Send register location + SPI.transfer(thisValue); //Send value to record into register + // take the chip select high to de-select: + digitalWrite(chipSelectPin, HIGH); +} \ No newline at end of file