Diff: Hotboards_temp.cpp

Revision:

0:83da47b7ed26

Child:

1:f850ee1083ba

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Hotboards_temp.cpp	Thu Mar 17 04:57:00 2016 +0000
@@ -0,0 +1,145 @@
+/*
+  Hotboards_temp.cpp - Driver to read and control a serial (i2c) temperature sensor, The Microchip
+  MCP9808 is the digital sensor to control, can be read it, set its resolution, shutdown and also
+  set alarms.
+  Hotboards eeprom board (http://hotboards.org)
+  Created by Diego Perez, March 19, 2016.
+  Released into the public domain.
+*/
+#include "Hotboards_temp.h"
+
+#define SENSOR_ADDR       (uint8_t)0x3E
+#define REG_CONFIG        (uint8_t)0x01
+#define REG_ALERT_UPPER   (uint8_t)0x02
+#define REG_ALERT_LOWER   (uint8_t)0x03
+#define REG_CRITICAL_TEMP (uint8_t)0x04
+#define REG_TEMPERATURE   (uint8_t)0x05
+#define REG_MANU_ID       (uint8_t)0x06
+#define REG_DEVICE_ID     (uint8_t)0x07
+#define REG_RESOLUTION    (uint8_t)0x08
+
+Hotboards_temp::Hotboards_temp( I2C &i2c, uint8_t address, uint8_t resolution )
+    : _i2c(i2c) 
+{
+    _address = address | 0x18;
+    _resolution = resolution;
+}
+
+bool Hotboards_temp::init( void )
+{
+    bool flag = 0; // lets assume device is not here
+    uint16_t val = readReg( REG_MANU_ID );
+    if( val == 0x0054 )
+    {
+        // device is presence, default set resolution
+        writeReg( REG_RESOLUTION, _resolution );
+        // clear configuration register (alarms included)
+        writeReg( REG_CONFIG, 0x00 );
+        flag = 1;
+    }
+    return flag;
+}
+
+float Hotboards_temp::read( void )
+{
+    uint16_t val;
+    float temp;
+
+    // read the Ta register
+    val = readReg( REG_TEMPERATURE );
+
+    // small algorithm to calculate tmeperature in Celcius
+    // borrowed from https://github.com/adafruit/Adafruit_MCP9808_Library/blob/master/Adafruit_MCP9808.cpp
+    temp = val & 0x0FFF;
+    temp /=  (float)16.0;
+    // check if a negative temperature
+    if( val & 0x1000 ) temp -= 256;
+
+    return temp;
+}
+
+void Hotboards_temp::setAlarms( float lower, float upper )
+{
+    // set alarm values
+    writeAlarm( REG_ALERT_UPPER, upper );
+    writeAlarm( REG_CRITICAL_TEMP, upper );
+    writeAlarm( REG_ALERT_LOWER, lower );
+
+    uint16_t val = readReg( REG_CONFIG );
+    // set alarm only in comparator mode with LAERT pin set to LOW
+    writeReg( REG_CONFIG, val | 0x0008 );
+}
+
+void Hotboards_temp::disableAlarms( void )
+{
+    uint16_t val = readReg( REG_CONFIG );
+    // just clear the Alert Output Control bit
+    writeReg( REG_CONFIG, val ^ 0x0008 );
+}
+
+void Hotboards_temp::shutdown( bool state )
+{
+    uint16_t val = readReg( REG_CONFIG );
+
+    if( state == HT_SENSOR_OFF )
+    {// shutdown, curretn under 1uA, and disable convertions
+       writeReg( REG_CONFIG, val | 0x0100 );
+    }
+    else
+    {// power on
+       writeReg( REG_CONFIG, val ^ 0x0100 );
+    }
+}
+
+void Hotboards_temp::setResolution( uint8_t resolution )
+{
+    resolution &= 0x03;
+    writeReg( REG_RESOLUTION, resolution << 8 );
+}
+
+float Hotboards_temp::CelsiusToFarenheit( float celsius )
+{
+    return celsius * (float)9.0 / (float)5.0 + 32;
+}
+
+float Hotboards_temp::FarenheitToCelsius( float farenheit )
+{
+    return ( farenheit - 32 ) * (float)5.0 / (float)9.0;
+}
+
+uint16_t Hotboards_temp::readReg( uint8_t reg )
+{
+    int val;
+    char buffer[3];
+
+    buffer[0] = reg;
+    _i2c.write( _address, buffer, 1, true );
+    _i2c.read( _address, buffer, 2, false );
+    
+    val = buffer[0] << 8;
+    val |= buffer[1];
+
+    return val;
+}
+
+void Hotboards_temp::writeReg( uint8_t reg, uint16_t val )
+{
+    char buffer[3] = { reg, val >> 8, val & 0x00FF };
+    
+    _i2c.write( _address, buffer, 3 );
+}
+
+void Hotboards_temp::writeAlarm( uint16_t reg, float temp )
+{
+    uint16_t val = 0x0000;
+    // check if negative temp
+    if( temp < 0 )
+    {
+        temp += (float)256.0;
+        // set sign bit
+        val = 0x1000;
+    }
+    // convert to binary
+    val |= (uint16_t)( temp *= (float)16.0 );
+    writeReg( reg, val );
+}