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authorThibaut VIARD <thibaut.viard@atmel.com>2011-06-21 00:20:43 +0200
committerThibaut VIARD <thibaut.viard@atmel.com>2011-06-21 00:20:43 +0200
commit0887b98f627500271b5ad8b3c4f6c7b90bc227ee (patch)
treeef8626954567ba22e392c68c8f3606416b07b5b5 /libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde
parent90c487402cefadb6a2aab907ab07075cbb759e34 (diff)
Moving all AVR specific libraries to hardware/avr
Diffstat (limited to 'libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.pde')
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+/*
+ 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);
+}
+