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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