mcpDac.h

/* Arduino WaveHC Library
 * Copyright (C) 2009 by William Greiman
 *
 * This file is part of the Arduino WaveHC Library
 *
 * This Library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This Library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with the Arduino WaveHC Library.  If not, see
 * <http://www.gnu.org/licenses/>.
 */
/**
 *  Macros and inline functions for MCP4921 DAC
 */
#ifndef mcpDac_h
#define mcpDac_h

#include <WavePinDefs.h>
#include <avr/io.h>

//------------------------------------------------------------------------------
#define mcpDacCsLow() MCP_DAC_CS_PORT &= ~_BV(MCP_DAC_CS_BIT)
#define mcpDacCsHigh() MCP_DAC_CS_PORT |= _BV(MCP_DAC_CS_BIT)

#define mcpDacSckLow() MCP_DAC_SCK_PORT &= ~_BV(MCP_DAC_SCK_BIT)
#define mcpDacSckHigh() MCP_DAC_SCK_PORT |= _BV(MCP_DAC_SCK_BIT)
#define mcpDacSckPulse()                                                       \
  {                                                                            \
    mcpDacSckHigh();                                                           \
    mcpDacSckLow();                                                            \
  }

#define mcpDacSdiLow() MCP_DAC_SDI_PORT &= ~_BV(MCP_DAC_SDI_BIT)
#define mcpDacSdiHigh() MCP_DAC_SDI_PORT |= _BV(MCP_DAC_SDI_BIT)
#define mcpDacSdiSet(v)                                                        \
  if (v) {                                                                     \
    mcpDacSdiHigh();                                                           \
  } else {                                                                     \
    mcpDacSdiLow();                                                            \
  }

// send bit b of d
#define mcpDacSendBit(d, b)                                                    \
  {                                                                            \
    mcpDacSdiSet(d &_BV(b));                                                   \
    mcpDacSckPulse();                                                          \
  }

//------------------------------------------------------------------------------
// init dac I/O ports
inline void mcpDacInit(void) {
  // set all to output mode
  MCP_DAC_CS_DDR |= _BV(MCP_DAC_CS_BIT);
  MCP_DAC_SCK_DDR |= _BV(MCP_DAC_SCK_BIT);
  MCP_DAC_SDI_DDR |= _BV(MCP_DAC_SDI_BIT);
  // chip select high
  mcpDacCsHigh();

#if USE_MCP_DAC_LDAC
  // LDAC low always - use unbuffered mode
  MCP_DAC_LDAC_DDR |= _BV(MCP_DAC_LDAC_BIT);
  MCP_DAC_LDAC_PORT &= ~_BV(MCP_DAC_LDAC_BIT);
#endif // USE_MCP_DAC_LDAC
}
//------------------------------------------------------------------------------
// send 12 bits to dac
// trusted compiler to optimize and it does
// csLow to csHigh takes 8 - 9 usec on a 16 MHz Arduino
inline void mcpDacSend(uint16_t data) {
  mcpDacCsLow();
  // send DAC config bits
  mcpDacSdiLow();
  mcpDacSckPulse(); // DAC A
  mcpDacSckPulse(); // unbuffered
  mcpDacSdiHigh();
  mcpDacSckPulse(); // 1X gain
  mcpDacSckPulse(); // no SHDN
  // send 12 data bits
  mcpDacSendBit(data, 11);
  mcpDacSendBit(data, 10);
  mcpDacSendBit(data, 9);
  mcpDacSendBit(data, 8);
  mcpDacSendBit(data, 7);
  mcpDacSendBit(data, 6);
  mcpDacSendBit(data, 5);
  mcpDacSendBit(data, 4);
  mcpDacSendBit(data, 3);
  mcpDacSendBit(data, 2);
  mcpDacSendBit(data, 1);
  mcpDacSendBit(data, 0);
  mcpDacCsHigh();
}

#endif // mcpDac_h