MCP4822.cpp

00001 #include "MCP4822.h"
00002 
00003 MCP4822::MCP4822(PinName dataout, PinName clock, PinName chipselect, PinName latch)  :
00004     cs(chipselect), latchpin(latch), spi(dataout, NC, clock)
00005       {
00006     cs = 1;
00007     latchpin = 1;
00008     spi.format(16);
00009 }
00010 
00011 void MCP4822::setA(float voltage)  {
00012     setvoltage(voltage);
00013 }
00014 
00015 void MCP4822::setB(float voltage)    {
00016     setvoltage(voltage, true);
00017 }
00018 
00019 void MCP4822::set(float voltageA, float voltageB)    {
00020     setvoltage(voltageA);
00021     setvoltage(voltageB, true);
00022 }
00023 
00024 void MCP4822::setvoltage(float voltage, bool chanB)    {
00025     int gain = 1;
00026     if (voltage > 2.048)    {
00027         gain = 2;
00028     }
00029     unsigned int v;
00030     v = (unsigned int) (voltage * 4096.0 / 2.048 / (float) gain);
00031     write(chanB, (gain == 1), v);
00032 }
00033 
00034 void MCP4822::latch()    {
00035     latchpin = 0;
00036     latchpin = 1;
00037 }
00038 
00039 
00040 void MCP4822::write(bool chanB, bool gain1, unsigned int voltage, bool shutdown)    {
00041     if (voltage < 4096) {
00042         int msg = 0x0000;
00043         if (chanB)  msg |= (0x1 << 15);
00044         if (gain1)  msg |= (0x1 << 13);
00045         if (!shutdown)   msg |= (0x1 << 12);
00046         msg |= voltage; 
00047         cs = 0;
00048         spi.write(msg);
00049         cs = 1;
00050     }
00051 }
00052 
00053 void MCP4822::shutdown()    {
00054     write(false, false, 0, true);
00055     write(true, false, 0, true);
00056 }
00057 
00058 void MCP4822::shutdownA()   {
00059     write(false, false, 0, true);
00060 }
00061 
00062 void MCP4822::shutdownB()   {
00063     write(true, false, 0, true);
00064 }
00065 
00066 void MCP4822::chipSel(){
00067     cs = !cs;
00068 }