mcp4725.cpp

00001 #include "mcp4725.h"
00002 #include "mbed.h"
00003 
00004 MCP4725::MCP4725(PinName sda, PinName scl, BusFrequency bus_frequency, int device_address_bits): _i2c_interface(sda, scl)
00005 {
00006     //Set the frequency
00007     int freq=0;
00008     switch(bus_frequency)
00009     {
00010         case Standard100kHz:
00011             freq = 100000;
00012             break;
00013         case Fast400kHz:
00014             freq = 400000;
00015             break;
00016         case HighSpeed3_4Mhz:
00017             freq = 3400000;
00018             break;
00019     }
00020     _i2c_interface.frequency(freq);
00021     
00022     // Assemble the full I2C device address.
00023     _device_address = 0xC0; // Prime the full device address with the device code.
00024     _device_address |= (device_address_bits<<1);
00025 }
00026 
00027 int MCP4725::read(enum PowerMode* mode, enum PowerMode* mode_eeprom, int* dac_value, int* dac_value_eeprom, bool* eeprom_write_in_progress)
00028 {
00029     char data[5];
00030     int result;
00031     
00032     // Read the raw data from the device.
00033     result = _i2c_interface.read(_device_address, data, sizeof(data)/sizeof(*data), false);
00034     
00035     // Parse the raw data, extracting our fields. Refer to MCP4725 ref manual, section 6.2
00036     if (result == 0)
00037     {
00038         *eeprom_write_in_progress = (data[0] & 0x80)? false:true;
00039         
00040         *mode = (enum PowerMode) ((data[0] & 0x06)>>1);
00041         
00042         *dac_value  = (data[1]<<4) + (data[2]>>4);
00043         
00044         *mode_eeprom = (enum PowerMode)((data[3] & 0x60)>>5);
00045         
00046         *dac_value_eeprom = ((data[3] & 0x0F) <<8) + data[4];
00047     }
00048      
00049     return result;
00050 }
00051 
00052 
00053 
00054 int MCP4725::write(float dac_value, enum PowerMode mode, bool writeToEeprom)
00055 {
00056 
00057     
00058     int dac_value_2 = (int) (0xFFF * (dac_value/5.029f) ); // Divide dac_value by the reference voltage // Optimally the reference voltage is exactly 5.0V but this is not the case here. // The Ref voltage is 5.029V
00059     char data[3]={0};
00060     int write_command;
00061     
00062     //Which write command are we to use?
00063     if (writeToEeprom == true)
00064     {
00065         //Write DAC Register and EEPROM
00066         write_command = 3;
00067     }
00068     else
00069     {
00070         //Write DAC Register
00071         write_command = 2;
00072     }
00073     
00074     //Assemble our three bytes of data - Refer to MCP4725 ref manual, section 6.
00075     data[0] = (write_command <<5) | ((int)mode<<1);
00076     data[1] = (dac_value_2>>4);
00077     data[2] = (dac_value_2<<4);
00078     
00079     // Now write them to the device.
00080     return _i2c_interface.write(_device_address, data, sizeof(data)/sizeof(*data), false);
00081 }