Diff: Adafruit_MAX31865.cpp

Revision:

0:9294dd756a0c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Adafruit_MAX31865.cpp	Sun Jun 11 04:00:56 2017 +0000
@@ -0,0 +1,207 @@
+/*************************************************** 
+  This is a library for the Adafruit PT100/P1000 RTD Sensor w/MAX31865
+
+  Designed specifically to work with the Adafruit RTD Sensor
+  ----> https://www.adafruit.com/products/3328
+
+  This sensor uses SPI to communicate, 4 pins are required to  
+  interface
+  Adafruit invests time and resources providing this open source code, 
+  please support Adafruit and open-source hardware by purchasing 
+  products from Adafruit!
+
+  Written by Limor Fried/Ladyada for Adafruit Industries.  
+  BSD license, all text above must be included in any redistribution
+  
+  Modified for mbed project - Dan Julio - 5/2017
+ ****************************************************/
+#include "Adafruit_MAX31865.h"
+
+Adafruit_MAX31865::Adafruit_MAX31865(swspi& spiO, int ssNum, PinName rdyPin)
+  :
+  ssN(ssNum),
+  spi(spiO)
+{
+  debug = false;
+  rdyP = new DigitalIn(rdyPin);
+}
+
+bool Adafruit_MAX31865::begin(max31865_numwires_t wires) {
+
+  /*
+  for (uint8_t i=0; i<8; i++) {
+    readRegister8(i);
+  }
+  */
+
+  setWires(wires);
+  enableBias(false);
+  autoConvert(false);
+  clearFault();
+
+  if (debug) {
+    printf("config: 0x%2x\r\n", readRegister8(MAX31865_CONFIG_REG));
+  }
+  return true;
+}
+
+
+uint8_t Adafruit_MAX31865::readFault(void) {
+  return readRegister8(MAX31865_FAULTSTAT_REG);
+}
+
+void Adafruit_MAX31865::clearFault(void) {
+  uint8_t t = readRegister8(MAX31865_CONFIG_REG);
+  t &= ~0x2C;
+  t |= MAX31865_CONFIG_FAULTSTAT;
+  writeRegister8(MAX31865_CONFIG_REG, t);
+}
+
+void Adafruit_MAX31865::enableBias(bool b) {
+  uint8_t t = readRegister8(MAX31865_CONFIG_REG);
+  if (b) {
+    t |= MAX31865_CONFIG_BIAS;       // enable bias
+  } else {
+    t &= ~MAX31865_CONFIG_BIAS;       // disable bias
+  }
+  writeRegister8(MAX31865_CONFIG_REG, t);
+}
+
+void Adafruit_MAX31865::autoConvert(bool b) {
+  uint8_t t = readRegister8(MAX31865_CONFIG_REG);
+  if (b) {
+    t |= MAX31865_CONFIG_MODEAUTO;       // enable autoconvert
+  } else {
+    t &= ~MAX31865_CONFIG_MODEAUTO;       // disable autoconvert
+  }
+  writeRegister8(MAX31865_CONFIG_REG, t);
+}
+
+void Adafruit_MAX31865::setWires(max31865_numwires_t wires ) {
+  uint8_t t = readRegister8(MAX31865_CONFIG_REG);
+  if (wires == MAX31865_3WIRE) {
+    t |= MAX31865_CONFIG_3WIRE;
+  } else {
+    // 2 or 4 wire
+    t &= ~MAX31865_CONFIG_3WIRE;
+  }
+  writeRegister8(MAX31865_CONFIG_REG, t);
+}
+
+float  Adafruit_MAX31865::temperature(float RTDnominal, float refResistor, uint16_t rtdVal) {
+  // http://www.analog.com/media/en/technical-documentation/application-notes/AN709_0.pdf
+
+  float Z1, Z2, Z3, Z4, Rt, temp;
+
+  if (rtdVal == 0) {
+    Rt = readRTD();
+  } else {
+    Rt = rtdVal;
+  }
+  Rt /= 32768;
+  Rt *= refResistor;
+  
+  if (debug) {
+    printf("Resistance: %1.4f\r\n", Rt);
+  }
+
+  Z1 = -RTD_A;
+  Z2 = RTD_A * RTD_A - (4 * RTD_B);
+  Z3 = (4 * RTD_B) / RTDnominal;
+  Z4 = 2 * RTD_B;
+
+  temp = Z2 + (Z3 * Rt);
+  temp = (sqrt(temp) + Z1) / Z4;
+  
+  if (temp >= 0) return temp;
+
+  // ugh.
+  float rpoly = Rt;
+
+  temp = -242.02f;
+  temp += 2.2228f * rpoly;
+  rpoly *= Rt;  // square
+  temp += (float) 2.5859e-3 * rpoly;
+  rpoly *= Rt;  // ^3
+  temp -= (float) 4.8260e-6 * rpoly;
+  rpoly *= Rt;  // ^4
+  temp -= (float) 2.8183e-8 * rpoly;
+  rpoly *= Rt;  // ^5
+  temp += (float) 1.5243e-10 * rpoly;
+
+  return temp;
+}
+
+
+bool Adafruit_MAX31865::isReady(uint16_t* rtdVal) {
+    if (rdyP->read() == 0) {
+        *rtdVal = readRegister16(MAX31865_RTDMSB_REG);
+        
+        // remove fault
+        *rtdVal >>= 1;
+        return true;
+    } else {
+        return false;
+    }
+}
+
+
+uint16_t Adafruit_MAX31865::readRTD (void) {
+  clearFault();
+  enableBias(true);
+  wait_ms(10);
+  uint8_t t = readRegister8(MAX31865_CONFIG_REG);
+  t |= MAX31865_CONFIG_1SHOT;      
+  writeRegister8(MAX31865_CONFIG_REG, t);
+  wait_ms(65);
+
+  uint16_t rtd = readRegister16(MAX31865_RTDMSB_REG);
+
+  // remove fault
+  rtd >>= 1;
+
+  return rtd;
+}
+
+/**********************************************/
+
+uint8_t Adafruit_MAX31865::readRegister8(uint8_t addr) {
+  return spi.spiRead(addr, 1, ssN);
+}
+
+uint16_t Adafruit_MAX31865::readRegister16(uint8_t addr) {
+  uint8_t buffer[2];
+  
+  spi.spiBurstRead(addr, buffer, 2, 1, ssN);
+
+  uint16_t ret = buffer[0];
+  ret <<= 8;
+  ret |=  buffer[1];
+  
+  return ret;
+}
+
+
+void Adafruit_MAX31865::readRegisterN(uint8_t addr, uint8_t buffer[], uint8_t n) {
+  addr &= 0x7F; // make sure top bit is not set
+
+  spi.spiBurstRead(addr, buffer, n, 1, ssN);
+
+  if (debug) {
+    printf("$0x%2x: ", addr);
+    while (n--) {
+        printf(" 0x%2x", *buffer++);
+    }
+    printf("\n");
+  }
+}
+
+
+void Adafruit_MAX31865::writeRegister8(uint8_t addr, uint8_t data) {
+  spi.spiWrite(addr, data, 1, ssN);
+
+  if (debug) {
+    printf("$0x%2x = 0x%2x\r\n", addr, data);
+  }
+}
+