[136] | 1 | /*
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| 2 | SCP1000 Barometric Pressure Sensor Display
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| 3 |
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| 4 | Serves the output of a Barometric Pressure Sensor as a web page.
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| 5 | Uses the SPI library. For details on the sensor, see:
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| 6 | http://www.sparkfun.com/commerce/product_info.php?products_id=8161
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| 7 | http://www.vti.fi/en/support/obsolete_products/pressure_sensors/
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| 8 |
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| 9 | This sketch adapted from Nathan Seidle's SCP1000 example for PIC:
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| 10 | http://www.sparkfun.com/datasheets/Sensors/SCP1000-Testing.zip
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| 11 |
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| 12 | Circuit:
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| 13 | SCP1000 sensor attached to pins 6,7, and 11 - 13:
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| 14 | DRDY: pin 6
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| 15 | CSB: pin 7
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| 16 | MOSI: pin 11
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| 17 | MISO: pin 12
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| 18 | SCK: pin 13
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| 19 |
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| 20 | created 31 July 2010
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| 21 | by Tom Igoe
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| 22 | */
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| 23 |
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| 24 | #include <Ethernet2.h>
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| 25 | // the sensor communicates using SPI, so include the library:
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| 26 | #include <SPI.h>
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| 27 |
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| 28 |
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| 29 | // assign a MAC address for the ethernet controller.
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| 30 | // fill in your address here:
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| 31 | byte mac[] = {
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| 32 | 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
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| 33 | };
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| 34 | // assign an IP address for the controller:
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| 35 | IPAddress ip(192, 168, 1, 20);
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| 36 | IPAddress gateway(192, 168, 1, 1);
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| 37 | IPAddress subnet(255, 255, 255, 0);
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| 38 |
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| 39 |
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| 40 | // Initialize the Ethernet server library
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| 41 | // with the IP address and port you want to use
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| 42 | // (port 80 is default for HTTP):
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| 43 | EthernetServer server(80);
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| 44 |
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| 45 |
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| 46 | //Sensor's memory register addresses:
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| 47 | const int PRESSURE = 0x1F; //3 most significant bits of pressure
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| 48 | const int PRESSURE_LSB = 0x20; //16 least significant bits of pressure
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| 49 | const int TEMPERATURE = 0x21; //16 bit temperature reading
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| 50 |
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| 51 | // pins used for the connection with the sensor
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| 52 | // the others you need are controlled by the SPI library):
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| 53 | const int dataReadyPin = 6;
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| 54 | const int chipSelectPin = 7;
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| 55 |
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| 56 | float temperature = 0.0;
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| 57 | long pressure = 0;
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| 58 | long lastReadingTime = 0;
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| 59 |
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| 60 | void setup() {
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| 61 | // start the SPI library:
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| 62 | SPI.begin();
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| 63 |
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| 64 | // start the Ethernet connection and the server:
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| 65 | Ethernet.begin(mac, ip);
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| 66 | server.begin();
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| 67 |
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| 68 | // initalize the data ready and chip select pins:
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| 69 | pinMode(dataReadyPin, INPUT);
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| 70 | pinMode(chipSelectPin, OUTPUT);
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| 71 |
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| 72 | Serial.begin(9600);
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| 73 |
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| 74 | //Configure SCP1000 for low noise configuration:
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| 75 | writeRegister(0x02, 0x2D);
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| 76 | writeRegister(0x01, 0x03);
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| 77 | writeRegister(0x03, 0x02);
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| 78 |
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| 79 | // give the sensor and Ethernet shield time to set up:
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| 80 | delay(1000);
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| 81 |
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| 82 | //Set the sensor to high resolution mode tp start readings:
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| 83 | writeRegister(0x03, 0x0A);
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| 84 |
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| 85 | }
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| 86 |
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| 87 | void loop() {
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| 88 | // check for a reading no more than once a second.
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| 89 | if (millis() - lastReadingTime > 1000) {
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| 90 | // if there's a reading ready, read it:
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| 91 | // don't do anything until the data ready pin is high:
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| 92 | if (digitalRead(dataReadyPin) == HIGH) {
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| 93 | getData();
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| 94 | // timestamp the last time you got a reading:
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| 95 | lastReadingTime = millis();
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| 96 | }
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| 97 | }
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| 98 |
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| 99 | // listen for incoming Ethernet connections:
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| 100 | listenForEthernetClients();
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| 101 | }
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| 102 |
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| 103 |
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| 104 | void getData() {
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| 105 | Serial.println("Getting reading");
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| 106 | //Read the temperature data
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| 107 | int tempData = readRegister(0x21, 2);
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| 108 |
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| 109 | // convert the temperature to celsius and display it:
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| 110 | temperature = (float)tempData / 20.0;
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| 111 |
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| 112 | //Read the pressure data highest 3 bits:
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| 113 | byte pressureDataHigh = readRegister(0x1F, 1);
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| 114 | pressureDataHigh &= 0b00000111; //you only needs bits 2 to 0
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| 115 |
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| 116 | //Read the pressure data lower 16 bits:
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| 117 | unsigned int pressureDataLow = readRegister(0x20, 2);
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| 118 | //combine the two parts into one 19-bit number:
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| 119 | pressure = ((pressureDataHigh << 16) | pressureDataLow) / 4;
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| 120 |
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| 121 | Serial.print("Temperature: ");
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| 122 | Serial.print(temperature);
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| 123 | Serial.println(" degrees C");
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| 124 | Serial.print("Pressure: " + String(pressure));
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| 125 | Serial.println(" Pa");
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| 126 | }
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| 127 |
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| 128 | void listenForEthernetClients() {
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| 129 | // listen for incoming clients
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| 130 | EthernetClient client = server.available();
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| 131 | if (client) {
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| 132 | Serial.println("Got a client");
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| 133 | // an http request ends with a blank line
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| 134 | boolean currentLineIsBlank = true;
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| 135 | while (client.connected()) {
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| 136 | if (client.available()) {
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| 137 | char c = client.read();
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| 138 | // if you've gotten to the end of the line (received a newline
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| 139 | // character) and the line is blank, the http request has ended,
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| 140 | // so you can send a reply
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| 141 | if (c == '\n' && currentLineIsBlank) {
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| 142 | // send a standard http response header
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| 143 | client.println("HTTP/1.1 200 OK");
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| 144 | client.println("Content-Type: text/html");
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| 145 | client.println();
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| 146 | // print the current readings, in HTML format:
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| 147 | client.print("Temperature: ");
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| 148 | client.print(temperature);
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| 149 | client.print(" degrees C");
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| 150 | client.println("<br />");
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| 151 | client.print("Pressure: " + String(pressure));
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| 152 | client.print(" Pa");
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| 153 | client.println("<br />");
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| 154 | break;
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| 155 | }
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| 156 | if (c == '\n') {
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| 157 | // you're starting a new line
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| 158 | currentLineIsBlank = true;
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| 159 | }
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| 160 | else if (c != '\r') {
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| 161 | // you've gotten a character on the current line
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| 162 | currentLineIsBlank = false;
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| 163 | }
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| 164 | }
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| 165 | }
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| 166 | // give the web browser time to receive the data
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| 167 | delay(1);
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| 168 | // close the connection:
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| 169 | client.stop();
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| 170 | }
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| 171 | }
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| 172 |
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| 173 |
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| 174 | //Send a write command to SCP1000
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| 175 | void writeRegister(byte registerName, byte registerValue) {
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| 176 | // SCP1000 expects the register name in the upper 6 bits
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| 177 | // of the byte:
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| 178 | registerName <<= 2;
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| 179 | // command (read or write) goes in the lower two bits:
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| 180 | registerName |= 0b00000010; //Write command
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| 181 |
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| 182 | // take the chip select low to select the device:
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| 183 | digitalWrite(chipSelectPin, LOW);
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| 184 |
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| 185 | SPI.transfer(registerName); //Send register location
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| 186 | SPI.transfer(registerValue); //Send value to record into register
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| 187 |
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| 188 | // take the chip select high to de-select:
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| 189 | digitalWrite(chipSelectPin, HIGH);
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| 190 | }
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| 191 |
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| 192 |
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| 193 | //Read register from the SCP1000:
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| 194 | unsigned int readRegister(byte registerName, int numBytes) {
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| 195 | byte inByte = 0; // incoming from the SPI read
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| 196 | unsigned int result = 0; // result to return
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| 197 |
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| 198 | // SCP1000 expects the register name in the upper 6 bits
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| 199 | // of the byte:
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| 200 | registerName <<= 2;
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| 201 | // command (read or write) goes in the lower two bits:
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| 202 | registerName &= 0b11111100; //Read command
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| 203 |
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| 204 | // take the chip select low to select the device:
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| 205 | digitalWrite(chipSelectPin, LOW);
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| 206 | // send the device the register you want to read:
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| 207 | int command = SPI.transfer(registerName);
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| 208 | // send a value of 0 to read the first byte returned:
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| 209 | inByte = SPI.transfer(0x00);
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| 210 |
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| 211 | result = inByte;
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| 212 | // if there's more than one byte returned,
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| 213 | // shift the first byte then get the second byte:
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| 214 | if (numBytes > 1) {
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| 215 | result = inByte << 8;
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| 216 | inByte = SPI.transfer(0x00);
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| 217 | result = result | inByte;
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| 218 | }
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| 219 | // take the chip select high to de-select:
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| 220 | digitalWrite(chipSelectPin, HIGH);
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| 221 | // return the result:
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| 222 | return(result);
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| 223 | }
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