MCP4922Single.cpp

00001 //------------------------------------------------------
00002 // Class for 1 DAC in MCP4922
00003 //
00004 // Copyright (c) 2014 MIKAMI, Naoki,  2014/06/18
00005 //------------------------------------------------------
00006 
00007 #include "MCP4922Single.hpp"
00008 
00009 namespace Mikami
00010 {
00011     Dac::Dac(DAC dac, PinName mosi, PinName sclk,
00012              PinName cs, PinName ldac, int hz)
00013         : wcr_(dac | 0x3000), mySpi_(mosi, NC, sclk),
00014           myCs_(cs, 1), myLd_(ldac, 0)
00015     {
00016         // Set SPI format and bus frequency
00017         mySpi_.format(16, 0);
00018         mySpi_.frequency(hz);
00019 
00020         // Set DAC to 0
00021         WriteDac(0);
00022     }
00023 
00024     void Dac::Write(float value)
00025     {
00026         if (value < -1.0f) value = -1.0f;
00027         if (value >  1.0f) value =  1.0f;
00028 
00029         WriteDac((uint16_t)((value + 1.0f)*2047));
00030     }
00031 
00032     void Dac::Write(uint16_t value)
00033     {
00034         WriteDac((value > 4095) ? 4095 : value);
00035     }
00036         
00037     void Dac::Ldac()
00038     {
00039         myLd_.write(0);
00040         wait_us(1);       
00041         myLd_.write(1);
00042     }
00043 
00044     void Dac::WriteDac(uint16_t value)
00045     {
00046         myCs_.write(0); // cs <= L
00047         mySpi_.write(value | wcr_);
00048         myCs_.write(1); // cs <= H
00049     }
00050 }