MCP320x.cpp

00001 #include "MCP320x.h"
00002 
00003 namespace MCP320x_SPI {
00004 
00005     unsigned char CMCP320x_SPI::SPIModuleRefCounter = 0;
00006 
00007     CMCP320x_SPI::CMCP320x_SPI(const PinName p_mosi, const PinName p_miso, const PinName p_sclk, const PinName p_cs, const Mcp320xFamilly p_familly, const unsigned int p_frequency) : _internalId("") {
00008         CMCP320x_SPI::SPIModuleRefCounter += 1;
00009         if (CMCP320x_SPI::SPIModuleRefCounter > 1) {
00010             //FIXME Check that SPI settings are identical. Otherwise it should failed
00011             return;
00012         }
00013 
00014         _familly = p_familly;
00015         switch (_familly) {
00016             case _3201:
00017                 _channelsNum = 1;
00018                 break;
00019             case _3204:
00020                 _channelsNum = 4;
00021                 break;
00022             default: // _3208
00023                 _channelsNum = 8;
00024         } // End of 'switch' statement
00025         _settings = 0x02; // SGL/DIFF bit set to 1 = See DS21298E-page 19 TABLE 5-1: CONFIGURATION BITS FOR THE MCP3204/TABLE 5-2: CONFIGURATION BITS FOR THE MCP3208
00026         _spiInstance = new SPI(p_mosi, p_miso, p_sclk);
00027         _spiInstance->frequency(p_frequency); // Set the frequency of the SPI interface
00028         _spiInstance->format(8, 3);
00029 
00030         if (p_cs != NC) {
00031             _cs = new DigitalOut(p_cs);
00032             _cs->write(1); // Disable chip
00033         } else {
00034             _cs = NULL; // Not used
00035         }
00036     
00037      }
00038     
00039     CMCP320x_SPI::~CMCP320x_SPI() {
00040         // Release I2C instance
00041         CMCP320x_SPI::SPIModuleRefCounter -= 1;
00042         if (CMCP320x_SPI::SPIModuleRefCounter == 0) {
00043             delete _spiInstance;
00044             _spiInstance = NULL;
00045         }
00046         // Release _reset if required
00047         if (_cs != NULL) {
00048             _cs->write(1);
00049             delete _cs;
00050         }
00051     }
00052 
00053     float CMCP320x_SPI::Read(const Mcp320xChannels p_channels) {
00054         
00055         // Read a sample
00056         _sample.value = 0x00;
00057         switch (_familly) {
00058             case _3204:
00059                 // No break;
00060             case _3208:
00061                 Read_320x(p_channels);
00062                 break;
00063             default: // _3201
00064                 Read_3201();
00065                 break;
00066         } // End of 'switch' statement 
00067          //_sample.value >>= 1; // Adjust composite integer for 12 valid bits
00068         _sample.value &= 0x0FFF; // Mask out upper nibble of integer
00069         
00070         return _sample.value;        
00071     }
00072     
00073     void CMCP320x_SPI::SetConfig(const bool p_settings) {
00074         
00075         if (_settings) {
00076             _settings = 0x02;
00077         } else {
00078             _settings = 0x00;
00079         }
00080     }
00081     
00082     bool CMCP320x_SPI::Shutdown(const bool p_shutdown) {
00083         // Sanity check
00084         if (_cs == NULL) {
00085             return false;
00086         }
00087         
00088         _cs->write(p_shutdown == false ? 0 : 1);
00089         
00090         return true;
00091     }
00092     
00093     void CMCP320x_SPI::Read_3201() {
00094         if (_cs != NULL) {
00095             _cs->write(0);
00096             wait_us(1);
00097         }
00098         _sample.bytes[1] = _spiInstance->write(0);
00099         _sample.bytes[0] = _spiInstance->write(0);
00100         if (_cs != NULL) {
00101             _cs->write(1);
00102         }    
00103     }
00104 
00105     void CMCP320x_SPI::Read_320x(const Mcp320xChannels p_channels) {
00106         
00107         unsigned char _channels = (unsigned char)p_channels % _channelsNum;
00108         // Set start bit 
00109         unsigned char mask = 0x04 | _settings; // Start bit set to 1 - See DS21298E-page 19 Clause 5.0 SERIAL COMMUNICATIONS
00110         // Set channel address
00111         unsigned char cmd0;
00112         unsigned char cmd1;
00113         if (_familly == _3204) {
00114             cmd0 = mask;
00115             cmd1 = _channels << 6; // MCP3204 has 4 channels in single-ended mode
00116         } else { // MCP3208
00117             cmd0 = mask | ((_channels & 0x04) >> 2); // Extract D2 bit - See DS21298E-page 19 Clause 5.0 SERIAL COMMUNICATIONS
00118             cmd1 = _channels << 6; // MCP3204 has 8 channels in single-ended mode
00119         }
00120         if (_cs != NULL) {
00121             _cs->write(0);
00122             wait_us(1);
00123         }
00124         _spiInstance->write(cmd0); // Don't care of the result - See DS21298E-page 21 Clause 6.1 Using the MCP3204/3208 with Microcontroller (MCU) SPI Ports
00125         _sample.bytes[1] = _spiInstance->write(cmd1); // DS21298E-page 21 See FIGURE 6-1: SPI Communication using 8-bit segments (Mode 0,0: SCLK idles low)
00126         _sample.bytes[0] = _spiInstance->write(0);
00127         if (_cs != NULL) {
00128             _cs->write(1);
00129         }
00130             
00131     }
00132     
00133 } // End of namespace MCP320x_SPI