Diff: LM77.cpp

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0:8e812deb9f66

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/LM77.cpp	Sat Jan 10 19:10:40 2015 +0000
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+/* mbed LM77 Library, for an I2C Temperature sensor
+ * Copyright (c) 2015, v01: WH, Initial version
+ * 
+ * The LM77 is a digital temperature sensor and thermal window comparator with an I2C Serial Bus interface. 
+ * The open-drain Interrupt (INT) output becomes active whenever temperature goes outside a programmable window,
+ * while a separate Critical Temperature Alarm (T_CRIT_A) output becomes active when the temperature exceeds a 
+ * programmable critical limit. The INT output can operate in either a comparator or event mode, while the T_CRIT_A 
+ * output operates in comparator mode only. The host can program both the upper and lower limits of the window as 
+ * well as the critical temperature limit. Programmable hysterisis as well as a fault queue are available to minimize 
+ * false tripping. Two pins (A0, A1) are available for address selection. The sensor powers up with default thresholds 
+ * of 2°C THYST, 10°C TLOW, 64°C THIGH, and 80°C TCRIT.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "LM77.h"
+
+/** Create an LM77 device instance
+  *
+  * @param i2c    I2C Bus 
+  * @param char deviceAddress I2C slaveaddress
+  */ 
+LM77::LM77(I2C *i2c, char deviceAddress) : _i2c(i2c), _slaveAddress(deviceAddress) {
+
+}
+
+/** Get Status
+ *
+ * @return bool Sensor ready 
+ */ 
+bool LM77::getStatus(void) {
+  char buffer[2];      
+  int status;
+    
+  // Dummy operation to check status
+  buffer[0] = 0x00;
+  status=_i2c->write(_slaveAddress, buffer, 0);
+
+  return (status==0);           // True when device found   
+}
+
+
+/** Get the current power mode of the LM77
+  *
+  * @returns The current power mode as a PowerMode enum.
+  */
+LM77::PowerMode LM77::getPowerMode() {
+
+    //Read the 8-bit register value
+    char value = _readReg8(LM77_REG_CONF);
+
+    //Return the status of the SHUTDOWN bit
+    if (value & LM77_PWR_MSK) {
+        return POWER_SHUTDOWN;
+    }    
+    else {
+        return POWER_NORMAL;
+    }    
+}
+
+
+/** Set the power mode of the LM77
+  *
+  * @param mode The new power mode as a PowerMode enum.
+  */
+void LM77::setPowerMode(PowerMode mode) {
+    
+    //Read the current 8-bit register value
+    char value = _readReg8(LM77_REG_CONF);
+
+    //Set or clear the SHUTDOWN bit
+    if (mode == POWER_SHUTDOWN) {
+        value |= LM77_PWR_DWN;
+    }    
+    else {
+        value &= ~LM77_PWR_DWN;
+    }    
+
+    //Write the value back out
+    _writeReg8(LM77_REG_CONF, value);
+}
+
+
+/** Get the current INT pin mode of the LM77
+  *
+  * @returns The current INT pin mode as an IntMode enum.
+  */
+LM77::IntMode LM77::getIntMode() {
+    
+    //Read the 8-bit register value
+    char value = _readReg8(LM77_REG_CONF);
+
+    //Return the status of the INT_MODE bit
+    if (value & LM77_INT_MSK) {
+        return INT_EVENT;
+    }    
+    else {
+        return INT_COMPARATOR;
+    }    
+}
+
+
+/** Set the INT pin mode of the LM77
+  *
+  * @param mode The new INT pin mode as an IntMode enum.
+  */
+void LM77::setIntMode(IntMode mode) {
+
+    //Read the current 8-bit register value
+    char value = _readReg8(LM77_REG_CONF);
+
+    //Set or clear the OS_COMP_INT bit
+    if (mode == INT_EVENT) {
+        value |= LM77_INT_EVENT;
+    }    
+    else {
+        // Comparator mode 
+        value &= ~LM77_INT_EVENT;
+    }    
+
+    //Write the value back out
+    _writeReg8(LM77_REG_CONF, value);
+}
+
+
+/** Get the current INT pin polarity of the LM77
+  *
+  * @returns The current INT pin polarity as an PinPolarity enum.
+  */
+LM77::PinPolarity LM77::getIntPolarity() {
+    
+    //Read the 8-bit register value
+    char value = _readReg8(LM77_REG_CONF);
+
+    //Return the status of the POL_INT bit
+    if (value & LM77_POL_INT_MSK) {
+        return ACTIVE_HIGH;
+    }    
+    else {
+        return ACTIVE_LOW;
+    }    
+}
+
+/** Set the INT pin polarity of the LM77
+  *
+  * @param polarity The new INT pin polarity as an PinPolarity enum.
+  */
+void LM77::setIntPolarity(PinPolarity polarity)
+{
+    //Read the current 8-bit register value
+    char value = _readReg8(LM77_REG_CONF);
+
+    //Set or clear the POL_INT bit
+    if (polarity == ACTIVE_HIGH) {
+        value |= LM77_POL_INT_H;
+    }    
+    else {
+        value &= ~LM77_POL_INT_H;
+    }    
+
+    //Write the value back out
+    _writeReg8(LM77_REG_CONF, value);
+}
+
+/** Get the current T_CRIT_A pin polarity of the LM77
+  *
+  * @returns The current T_CRIT_A pin polarity as an PinPolarity enum.
+  */
+LM77::PinPolarity LM77::getTCritPolarity() {
+    
+    //Read the 8-bit register value
+    char value = _readReg8(LM77_REG_CONF);
+
+    //Return the status of the POL_TCRIT bit
+    if (value & LM77_POL_TCRIT_MSK) {
+        return ACTIVE_HIGH;
+    }    
+    else {
+        return ACTIVE_LOW;
+    }    
+}
+
+/** Set the T_CRIT_A pin polarity of the LM77
+  *
+  * @param polarity The new T_CRIT_A pin polarity as an PinPolarity enum.
+  */
+void LM77::setTCritPolarity(PinPolarity polarity)
+{
+    //Read the current 8-bit register value
+    char value = _readReg8(LM77_REG_CONF);
+
+    //Set or clear the POL_TCRIT bit
+    if (polarity == ACTIVE_HIGH) {
+        value |= LM77_POL_TCRIT_H;
+    }    
+    else {
+        value &= ~LM77_POL_TCRIT_H;
+    }    
+
+    //Write the value back out
+    _writeReg8(LM77_REG_CONF, value);
+}
+
+
+/** Get the current pin and flag fault queue length of the LM77
+  *
+  * @returns The current pin and flag fault queue length as an FaultQueue enum.
+  */
+LM77::FaultQueue LM77::getFaultQueue()
+{
+    //Read the 8-bit register value
+    char value = _readReg8(LM77_REG_CONF);
+
+    //Return the status of the FAULT_QUE bit
+    if (value & LM77_FQU_MSK) {
+        return FAULT_QUEUE_4;
+    }    
+    else {
+        return FAULT_QUEUE_1;
+    }    
+}
+
+
+/** Set the pin and flag fault queue length of the LM77
+  *
+  * @param queue The new pin and flag fault queue length as an FaultQueue enum.
+  */
+void LM77::setFaultQueue(FaultQueue queue)
+{
+    //Read the current 8-bit register value
+    char value = _readReg8(LM77_REG_CONF);
+
+    //Set the new FAULT_QUE bit
+    if (queue == FAULT_QUEUE_4) {
+        value |= LM77_FQU_4;
+    }    
+    else {
+        value &= ~LM77_FQU_4;
+    }    
+
+    //Write the value back out
+    _writeReg8(LM77_REG_CONF, value);
+}
+
+/** Get the current Critical alert temperature threshold of the LM77
+  * Reset value is 80.0 °C.   
+  *
+  * @returns The current Critical alert temperature threshold in °C.
+  */
+float LM77::getCritAlertTemp() {
+    
+  //Use the 9-bit helper to read the TCRIT register
+  return _readTempHelper(LM77_REG_TCRIT);
+}
+
+/** Set the critical alert temperature threshold of the LM77
+  * Reset value is 80.0 °C.   
+  *
+  * @param temp The new critical alert temperature threshold in °C.
+  */
+void LM77::setCritAlertTemp(float temp) {
+    
+  //Use the 9-bit helper to write to the TCRIT register
+  _writeTempHelper(LM77_REG_TCRIT, temp);
+}
+
+/** Get the current Low temperature alert threshold of the LM77
+  * Reset value is 10.0 °C.   
+  *
+  * @returns The current Low temperature alert threshold in °C.
+  */
+float LM77::getLowAlertTemp() {
+
+  //Use the 9-bit helper to read the TLOW register
+  return _readTempHelper(LM77_REG_TLOW);
+}
+
+/** Set the current Low temperature alert threshold of the LM77
+  * Reset value is 10.0 °C.   
+  *
+  * @param temp The new Low alert temperature threshold in °C.
+  */
+void LM77::setLowAlertTemp(float temp){
+  
+  //Use the 9-bit helper to write to the TLOW register  
+  _writeTempHelper(LM77_REG_TLOW, temp);
+}    
+
+/** Get the current High temperature alert threshold of the LM77
+  * Reset value is 64.0 °C.   
+  *
+  * @returns The current High temperature alert threshold in °C.
+  */
+float LM77::getHighAlertTemp(){
+
+  //Use the 9-bit helper to read the THIGH register
+  return _readTempHelper(LM77_REG_THIGH);
+}    
+    
+/** Set the High temperature alert threshold of the LM77
+  * Reset value is 64.0 °C.   
+  *
+  * @param temp The new High temperature alert threshold in °C.
+  */
+void LM77::setHighAlertTemp(float temp) {
+
+  //Use the 9-bit helper to write to the THIGH register  
+  _writeTempHelper(LM77_REG_THIGH, temp);   
+}
+
+
+/** Get the current alert temperature hysteresis of the LM77
+  * Reset value is 2.0 °C.
+  *
+  * @returns The current alert temperature hysteresis in °C.
+  */ 
+float LM77::getAlertHyst() {
+    
+  //Use the 9-bit helper to read the THYST register
+  return _readTempHelper(LM77_REG_THYST);
+}
+
+/** Set the alert temperature hysteresis of the LM77
+  * Reset value is 2.0 °C.
+  *
+  * @param temp The new alert temperature hysteresis in °C.
+  */
+void LM77::setAlertHyst(float temp) {
+    
+  //Use the 9-bit helper to write to the THYST register
+  _writeTempHelper(LM77_REG_THYST, temp);
+}
+
+
+/** Get Temperature as int in °Celsius x 10
+  *
+  * @return int Temperature in °Celsius x 10
+  */ 
+int LM77::getTemperatureInt(void) {
+  
+    //Signed return value
+    int16_t value;
+
+    //Read the 9-bit raw temperature value in 0.5 degree resolution
+    value = _readReg16(LM77_REG_TEMP) >> 3;
+
+    //Sign extend negative numbers
+    if (value & (1 << 9))
+        value |= 0xFE00;
+
+    //Return the temperature in °C x 10
+    return (int) value * 5;    // x 10 x 0.5
+}
+
+/** Get the Alert flags of the LM77
+  *
+  * @returns The current Alert flags as int.
+  */
+int LM77::getAlertFlags() {
+
+    //Signed return value
+    int16_t value;
+
+    //Read the 9-bit raw temperature value and the flags
+    value = _readReg16(LM77_REG_TEMP);
+    
+    //Return the flag bits
+    // LM77_FLAG_LOW    0x01
+    // LM77_FLAG_HIGH   0x02
+    // LM77_FLAG_CRIT   0x04
+    // LM77_FLAG_MSK    0x07   
+    return (value & LM77_FLAG_MSK);
+}
+
+
+/** Get Temperature as float in °Celsius
+  *
+  * @return float Temperature in °Celsius
+  */ 
+float LM77::getTemperature(void) {
+  
+  return _readTempHelper(LM77_REG_TEMP);
+}
+
+#ifdef MBED_OPERATORS
+LM77::operator float() {
+
+  //Return the current temperature reading
+  return getTemperature();
+}
+#endif
+
+/** Convert Temperature from °Celsius into °Fahrenheit
+  *
+  * @param  float celsius in °Celsius  
+  * @return float temperature in °Fahrenheit
+  */ 
+float LM77::celsiusToFahrenheit(float celsius) {
+  
+  return ((celsius * 9.0f) / 5.0f) + 32.0f; // Convert to Fahrenheit
+}
+
+
+/** Read 8 bit value from register
+  *
+  * @param reg Index of register
+  * @return data value from register
+  */     
+char LM77::_readReg8(char reg) {
+    
+    //Select the register
+    _i2c->write(_slaveAddress, &reg, 1, true);
+
+    //Read the 8-bit register
+    _i2c->read(_slaveAddress, &reg, 1);
+
+    //Return the byte
+    return reg;
+}
+
+/** Write 8 bit value to register
+  *
+  * @param reg Index of register
+  * @param data value to write
+  */     
+void LM77::_writeReg8(char reg, char data) {
+    
+    //Create a temporary buffer
+    char buf[2];
+
+    //Load the register address and 8-bit data
+    buf[0] = reg;
+    buf[1] = data;
+
+    //Write the data
+    _i2c->write(_slaveAddress, buf, 2);
+}
+
+/** Read 16 bit value from register
+  * Used for Critical temp threshold, Low and High temp threshold window and Hysteresis
+  *
+  * @param reg Index of register
+  * @return data value from register  
+  */     
+int16_t LM77::_readReg16(char reg) {
+    
+    //Create a temporary buffer
+    char buf[2];
+    
+    //Select the register
+    _i2c->write(_slaveAddress, &reg, 1, true);
+
+    //Read the 16-bit register
+    _i2c->read(_slaveAddress, buf, 2);
+
+    //Return the combined 16-bit value
+    return (buf[0] << 8) | buf[1];
+}
+
+/** Write 16 bit value to register
+  * Used for Critical temp threshold, Low and High temp threshold window and Hysteresis
+  *
+  * @param reg Index of register
+  * @param data value to write
+  */     
+void LM77::_writeReg16(char reg, int16_t data) {
+    
+    //Create a temporary buffer
+    char buf[3];
+
+    //Load the register address and 16-bit data
+    buf[0] = reg;
+    buf[1] = data >> 8;
+    buf[2] = data;
+
+    //Write the data
+    _i2c->write(_slaveAddress, buf, 3);    
+}
+
+/** Get Temperature as float in °Celsius
+  * Used for Critical temp threshold, Low and High temp threshold window and Hysteresis
+  *
+  * @param reg Index of register to read temp value
+  * @return float Temperature in °Celsius
+  */     
+float LM77::_readTempHelper(char reg) {
+
+    //Signed return value
+    int16_t value;
+       
+#if(1)
+    //Read the 9-bit raw temperature value in 0.5 degree resolution
+    value = _readReg16(reg) >> 3;
+#else
+    int16_t readreg;
+    
+    //Test neg temps
+    readreg   = 0xFE70;  //-25 degree
+    value = readreg >> 3;
+#endif   
+    
+    //Sign extend negative numbers
+    if (value & (1 << 9))
+        value |= 0xFE00;
+
+    //Return the temperature in °C
+    return (float) value * 0.5f; 
+}
+
+
+/** Set Temperature as float in °Celsius
+ * Used for Critical temp threshold, Low and High temp threshold window and Hysteresis
+ *
+ * @param reg Index of register to write temp value
+ * @param temp float Temperature value in °Celsius
+ */        
+void LM77::_writeTempHelper(char reg, float temp) {
+    //Signed value
+    int16_t value;    
+
+    //Range limit temp
+    if (temp < -55.0)
+        temp = -55.0;
+    else if (temp > 125.0)
+        temp = 125.0;
+
+    //Extract and shift the signed integer
+    value =  temp * 2.0f;
+    value <<= 3;
+
+    //Send the new value
+    _writeReg16(reg, value);
+}
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