DS1920.cpp

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00032 
00033 #include <MaximInterfaceCore/Error.hpp>
00034 #include <MaximInterfaceCore/OneWireMaster.hpp>
00035 #include "DS1920.hpp"
00036 
00037 namespace MaximInterfaceDevices {
00038 
00039 using namespace Core;
00040 
00041 Result<void> DS1920::writeScratchpad(uint_least8_t th, uint_least8_t tl) {
00042   Result<void> result = selectRom(*master);
00043   if (result) {
00044     const uint_least8_t sendBlock[] = {0x4E, th, tl};
00045     result = master->writeBlock(sendBlock);
00046   }
00047   return result;
00048 }
00049 
00050 Result<DS1920::Scratchpad> DS1920::readScratchpad() const {
00051   Result<void> result = selectRom(*master);
00052   if (!result) {
00053     return result.error();
00054   }
00055   result = master->writeByte(0xBE);
00056   if (!result) {
00057     return result.error();
00058   }
00059   Scratchpad scratchpad;
00060   result = master->readBlock(scratchpad);
00061   if (!result) {
00062     return result.error();
00063   }
00064   uint_least8_t receivedCrc;
00065   MaximInterfaceCore_TRY_VALUE(receivedCrc, master->readByte());
00066   if (receivedCrc != calculateCrc8(scratchpad)) {
00067     return CrcError;
00068   }
00069   return scratchpad;
00070 }
00071 
00072 Result<void> DS1920::copyScratchpad() {
00073   Result<void> result = selectRom(*master);
00074   if (result) {
00075     result = master->writeByteSetLevel(0x48, OneWireMaster::StrongLevel);
00076     if (result) {
00077       sleep->invoke(10);
00078       result = master->setLevel(OneWireMaster::NormalLevel);
00079     }
00080   }
00081   return result;
00082 }
00083 
00084 Result<void> DS1920::convertTemperature() {
00085   Result<void> result = selectRom(*master);
00086   if (result) {
00087     result = master->writeByteSetLevel(0x44, OneWireMaster::StrongLevel);
00088     if (result) {
00089       sleep->invoke(750);
00090       result = master->setLevel(OneWireMaster::NormalLevel);
00091     }
00092   }
00093   return result;
00094 }
00095 
00096 Result<void> DS1920::recallEeprom() {
00097   Result<void> result = selectRom(*master);
00098   if (result) {
00099     result = master->writeByte(0xB8);
00100   }
00101   return result;
00102 }
00103 
00104 const error_category & DS1920::errorCategory() {
00105   static class : public error_category {
00106   public:
00107     virtual const char * name() const { return "MaximInterfaceDevices.DS1920"; }
00108 
00109     virtual std::string message(int condition) const {
00110       switch (condition) {
00111       case CrcError:
00112         return "CRC Error";
00113 
00114       case DataError:
00115         return "Data Error";
00116       }
00117       return defaultErrorMessage(condition);
00118     }
00119   } instance;
00120   return instance;
00121 }
00122 
00123 Result<int> readTemperature(DS1920 & ds1920) {
00124   MaximInterfaceCore_TRY(ds1920.convertTemperature());
00125   DS1920::Scratchpad scratchpad;
00126   MaximInterfaceCore_TRY_VALUE(scratchpad, ds1920.readScratchpad());
00127 
00128   unsigned int tempData =
00129       (static_cast<unsigned int>(scratchpad[1]) << 8) | scratchpad[0];
00130   const unsigned int signMask = 0xFF00;
00131   int temperature;
00132   if ((tempData & signMask) == signMask) {
00133     temperature = -0x100;
00134     tempData &= ~signMask;
00135   } else if ((tempData & signMask) == 0) {
00136     temperature = 0;
00137   } else {
00138     return DS1920::DataError;
00139   }
00140   temperature += static_cast<int>(tempData);
00141   return temperature;
00142 }
00143 
00144 } // namespace MaximInterfaceDevices