MCP4822.cpp

00001 /* mbed MCP4822 Library, for driving the 12-Bit DAC with internal Vref and SPI interface
00002  * Copyright (c) 2015, Created by Steen Joergensen (stjo2809)
00003  *
00004  * Permission is hereby granted, free of charge, to any person obtaining a copy
00005  * of this software and associated documentation files (the "Software"), to deal
00006  * in the Software without restriction, including without limitation the rights
00007  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00008  * copies of the Software, and to permit persons to whom the Software is
00009  * furnished to do so, subject to the following conditions:
00010  *
00011  * The above copyright notice and this permission notice shall be included in
00012  * all copies or substantial portions of the Software.
00013  *
00014  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00015  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00016  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00017  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00018  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00019  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00020  * THE SOFTWARE.
00021  */
00022  
00023  #include "mbed.h"
00024  #include "MCP4822.h"
00025  
00026 //=============================================================================
00027 // Public functions
00028 //=============================================================================
00029 
00030     MCP4822::MCP4822(SPI& spi, PinName nLDAC, PinName nCs) : _spi(spi), _nLDAC(nLDAC), _nCs(nCs)
00031     {
00032         
00033     }
00034     
00035     
00036     MCP4822::MCP4822(PinName nLDAC, PinName mosi, PinName miso,PinName sck, PinName nCs) : _nLDAC(nLDAC), _mosi(mosi), _miso(miso), _sck(sck), _nCs(nCs)
00037     {
00038         SPI _spi(_mosi,_miso,_sck);    
00039     }
00040     
00041     void MCP4822::a(bool gain, int data)
00042     {
00043         _write(0, gain, 1, data);    
00044     }
00045     
00046     void MCP4822::b(bool gain, int data)
00047     {
00048         _write(1, gain, 1, data);     
00049     }
00050    
00051     void MCP4822::ldac(bool act)
00052     {
00053         _nLDAC = ~act;    
00054     }
00055     
00056     void MCP4822::shdn(bool output, bool act)
00057     {
00058         _write(output, 1, ~act, 0x00);    
00059     }
00060     
00061 //=============================================================================
00062 // Private functions
00063 //=============================================================================
00064 
00065     char MCP4822::_make_upper_half(bool output, bool gain, bool shdn, int data)
00066     {
00067         char responce = 0;
00068         
00069         if(output == '0')
00070         {
00071             responce = responce | CB_OUTPUT_A;        
00072         }
00073         else
00074         {
00075             responce = responce | CB_OUTPUT_B;      
00076         }
00077         
00078         if(gain == '0')
00079         {
00080             responce = responce | CB_GAIN_2X;        
00081         }
00082         else
00083         {
00084             responce = responce | CB_GAIN_1X;      
00085         }
00086         
00087         if(shdn == '0')
00088         {
00089             responce = responce | CB_NSHDN;        
00090         }
00091         else
00092         {
00093             responce = responce | CB_SHDN;      
00094         }
00095         
00096         if(data > 0xff && data < 0xfff)
00097         {
00098             responce = responce | (data >> 8);        
00099         }
00100         
00101         return responce;     
00102     }
00103     
00104     char MCP4822::_make_lower_half(int data)
00105     {
00106       return (data & 0xff);    
00107     }
00108     
00109     void MCP4822::_write(bool output, bool gain, bool shdn, int data)  
00110     {
00111         
00112         _upper_half = _make_upper_half(output, gain, shdn, data);
00113         _lower_half = _make_lower_half(data);
00114         
00115         _nCs = 0;
00116         _spi.write(_upper_half);
00117         _spi.write(_lower_half);
00118         _nCs = 1;    
00119     }