MCP9808.cpp

00001 #include "MCP9808.h"
00002 
00003 //***********************************/************************************
00004 //                              Constant                                //
00005 //***********************************/************************************
00006 #define MCP9808_I2C_ADDR    0x30 //( 18<<1)
00007 
00008 #define MCP9808_REG_CONFIG  0x01
00009 #define MCP9808_REG_TUPPER  0x02
00010 #define MCP9808_REG_TLOWER  0x03
00011 #define MCP9808_REG_TCRIT   0x04
00012 #define MCP9808_REG_TAMB    0x05
00013 #define MCP9808_REG_MANID   0x06
00014 #define MCP9808_REG_DEVID   0x07
00015 #define MCP9808_REG_RESOL   0x08
00016 
00017 #define MCP9808_TAMB_MASK   0x0F
00018 #define MCP9808_SIGN_POS    0x03
00019 
00020 //***********************************/************************************
00021 //                         Constructors                                 //
00022 //***********************************/************************************
00023 MCP9808::MCP9808(I2C *i2c, bool a0, bool a1, bool a2):_i2c(i2c)
00024 {
00025     _addr = (MCP9808_I2C_ADDR | (a2<<3) | (a1<<2) | (a0<<1));
00026 }
00027 
00028 float MCP9808::getTemp(void)
00029 {
00030     char reg = MCP9808_REG_TAMB;
00031     float ta;
00032     char buf[2];
00033 
00034     _i2c->write(_addr, &reg, 1);
00035     _i2c->read(_addr, buf, 2);
00036     
00037     /*
00038     if(buf[0] & (1<<MCP9808_SIGN_POS))
00039     {
00040         buf[0] &= MCP9808_TAMB_MASK;
00041         
00042         ta = 256 - (buf[0]*16 + buf[1]*0.0625); 
00043     }
00044     else
00045     {
00046         buf[0] &= MCP9808_TAMB_MASK;
00047         ta = (buf[0]*16 + buf[1]*0.0625);
00048     }*/
00049     
00050     ta = ((buf[0]&MCP9808_TAMB_MASK) << 8) | buf[1];
00051     ta /= 16.0;
00052     
00053     if(buf[0] & (1<<MCP9808_SIGN_POS))
00054     {
00055         ta -= 256;
00056     }
00057       
00058     return ta;  
00059 }
00060