source: arduino-1-6-7/trunk/fuentes/arduino-ide-amd64/hardware/arduino/avr/libraries/SPI/examples/BarometricPressureSensor/BarometricPressureSensor.ino @ 4837

Last change on this file since 4837 was 4837, checked in by daduve, 3 years ago

Adding new version

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1/*
2 SCP1000 Barometric Pressure Sensor Display
3
4 Shows the output of a Barometric Pressure Sensor on a
5 Uses the SPI library. For details on the sensor, see:
6 http://www.sparkfun.com/commerce/product_info.php?products_id=8161
7 http://www.vti.fi/en/support/obsolete_products/pressure_sensors/
8
9 This sketch adapted from Nathan Seidle's SCP1000 example for PIC:
10 http://www.sparkfun.com/datasheets/Sensors/SCP1000-Testing.zip
11
12 Circuit:
13 SCP1000 sensor attached to pins 6, 7, 10 - 13:
14 DRDY: pin 6
15 CSB: pin 7
16 MOSI: pin 11
17 MISO: pin 12
18 SCK: pin 13
19
20 created 31 July 2010
21 modified 14 August 2010
22 by Tom Igoe
23 */
24
25// the sensor communicates using SPI, so include the library:
26#include <SPI.h>
27
28//Sensor's memory register addresses:
29const int PRESSURE = 0x1F;      //3 most significant bits of pressure
30const int PRESSURE_LSB = 0x20;  //16 least significant bits of pressure
31const int TEMPERATURE = 0x21;   //16 bit temperature reading
32const byte READ = 0b11111100;     // SCP1000's read command
33const byte WRITE = 0b00000010;   // SCP1000's write command
34
35// pins used for the connection with the sensor
36// the other you need are controlled by the SPI library):
37const int dataReadyPin = 6;
38const int chipSelectPin = 7;
39
40void setup() {
41  Serial.begin(9600);
42
43  // start the SPI library:
44  SPI.begin();
45
46  // initalize the  data ready and chip select pins:
47  pinMode(dataReadyPin, INPUT);
48  pinMode(chipSelectPin, OUTPUT);
49
50  //Configure SCP1000 for low noise configuration:
51  writeRegister(0x02, 0x2D);
52  writeRegister(0x01, 0x03);
53  writeRegister(0x03, 0x02);
54  // give the sensor time to set up:
55  delay(100);
56}
57
58void loop() {
59  //Select High Resolution Mode
60  writeRegister(0x03, 0x0A);
61
62  // don't do anything until the data ready pin is high:
63  if (digitalRead(dataReadyPin) == HIGH) {
64    //Read the temperature data
65    int tempData = readRegister(0x21, 2);
66
67    // convert the temperature to celsius and display it:
68    float realTemp = (float)tempData / 20.0;
69    Serial.print("Temp[C]=");
70    Serial.print(realTemp);
71
72
73    //Read the pressure data highest 3 bits:
74    byte  pressure_data_high = readRegister(0x1F, 1);
75    pressure_data_high &= 0b00000111; //you only needs bits 2 to 0
76
77    //Read the pressure data lower 16 bits:
78    unsigned int pressure_data_low = readRegister(0x20, 2);
79    //combine the two parts into one 19-bit number:
80    long pressure = ((pressure_data_high << 16) | pressure_data_low) / 4;
81
82    // display the temperature:
83    Serial.println("\tPressure [Pa]=" + String(pressure));
84  }
85}
86
87//Read from or write to register from the SCP1000:
88unsigned int readRegister(byte thisRegister, int bytesToRead) {
89  byte inByte = 0;           // incoming byte from the SPI
90  unsigned int result = 0;   // result to return
91  Serial.print(thisRegister, BIN);
92  Serial.print("\t");
93  // SCP1000 expects the register name in the upper 6 bits
94  // of the byte. So shift the bits left by two bits:
95  thisRegister = thisRegister << 2;
96  // now combine the address and the command into one byte
97  byte dataToSend = thisRegister & READ;
98  Serial.println(thisRegister, BIN);
99  // take the chip select low to select the device:
100  digitalWrite(chipSelectPin, LOW);
101  // send the device the register you want to read:
102  SPI.transfer(dataToSend);
103  // send a value of 0 to read the first byte returned:
104  result = SPI.transfer(0x00);
105  // decrement the number of bytes left to read:
106  bytesToRead--;
107  // if you still have another byte to read:
108  if (bytesToRead > 0) {
109    // shift the first byte left, then get the second byte:
110    result = result << 8;
111    inByte = SPI.transfer(0x00);
112    // combine the byte you just got with the previous one:
113    result = result | inByte;
114    // decrement the number of bytes left to read:
115    bytesToRead--;
116  }
117  // take the chip select high to de-select:
118  digitalWrite(chipSelectPin, HIGH);
119  // return the result:
120  return (result);
121}
122
123
124//Sends a write command to SCP1000
125
126void writeRegister(byte thisRegister, byte thisValue) {
127
128  // SCP1000 expects the register address in the upper 6 bits
129  // of the byte. So shift the bits left by two bits:
130  thisRegister = thisRegister << 2;
131  // now combine the register address and the command into one byte:
132  byte dataToSend = thisRegister | WRITE;
133
134  // take the chip select low to select the device:
135  digitalWrite(chipSelectPin, LOW);
136
137  SPI.transfer(dataToSend); //Send register location
138  SPI.transfer(thisValue);  //Send value to record into register
139
140  // take the chip select high to de-select:
141  digitalWrite(chipSelectPin, HIGH);
142}
143
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