diff options
author | Thibaut VIARD <thibaut.viard@atmel.com> | 2011-06-21 00:20:43 +0200 |
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committer | Thibaut VIARD <thibaut.viard@atmel.com> | 2011-06-21 00:20:43 +0200 |
commit | 0887b98f627500271b5ad8b3c4f6c7b90bc227ee (patch) | |
tree | ef8626954567ba22e392c68c8f3606416b07b5b5 /libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde | |
parent | 90c487402cefadb6a2aab907ab07075cbb759e34 (diff) |
Moving all AVR specific libraries to hardware/avr
Diffstat (limited to 'libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde')
-rw-r--r-- | libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde b/libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde new file mode 100644 index 0000000..9d77a42 --- /dev/null +++ b/libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde @@ -0,0 +1,143 @@ +/* + 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 <SPI.h> + +//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 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): +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)); + } +} + +//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 + Serial.print(thisRegister, BIN); + Serial.print("\t"); + // 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 + byte dataToSend = thisRegister & READ; + Serial.println(thisRegister, BIN); + // 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 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: + 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); +} + |