text: /*
   * max5322.c:
   *	Extend wiringPi with the MAX5322 SPI Digital to Analog convertor
   *	Copyright (c) 2012-2013 Gordon Henderson
   ***********************************************************************
   * This file is part of wiringPi:
   *	https://projects.drogon.net/raspberry-pi/wiringpi/
   *
   *    wiringPi is free software: you can redistribute it and/or modify
   *    it under the terms of the GNU Lesser General Public License as
   *    published by the Free Software Foundation, either version 3 of the
   *    License, or (at your option) any later version.
   *
   *    wiringPi 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 Lesser General Public License for more details.
   *
   *    You should have received a copy of the GNU Lesser General Public
   *    License along with wiringPi.
   *    If not, see <http://www.gnu.org/licenses/>.
   ***********************************************************************
   */
  
  #include <wiringPi.h>
  #include <wiringPiSPI.h>
  
  #include "max5322.h"
  
  /*
   * myAnalogWrite:
   *	Write analog value on the given pin
   *********************************************************************************
   */
  
  static void myAnalogWrite (struct wiringPiNodeStruct *node, int pin, int value)
  {
    unsigned char spiData [2] ;
    unsigned char chanBits, dataBits ;
    int chan = pin - node->pinBase ;
  
    if (chan == 0)
      chanBits = 0b01000000 ;
    else
      chanBits = 0b01010000 ;
  
    chanBits |= ((value >> 12) & 0x0F) ;
    dataBits  = ((value      ) & 0xFF) ;
  
    spiData [0] = chanBits ;
    spiData [1] = dataBits ;
  
    wiringPiSPIDataRW (node->fd, spiData, 2) ;
  }
  
  /*
   * max5322Setup:
   *	Create a new wiringPi device node for an max5322 on the Pi's
   *	SPI interface.
   *********************************************************************************
   */
  
  int max5322Setup (const int pinBase, int spiChannel)
  {
    struct wiringPiNodeStruct *node ;
    unsigned char spiData [2] ;
  
    if (wiringPiSPISetup (spiChannel, 8000000) < 0)	// 10MHz Max
      return -1 ;
  
    node = wiringPiNewNode (pinBase, 2) ;
  
    node->fd          = spiChannel ;
    node->analogWrite = myAnalogWrite ;
  
  // Enable both DACs
  
    spiData [0] = 0b11100000 ;
    spiData [1] = 0 ;
    
    wiringPiSPIDataRW (node->fd, spiData, 2) ;
  
    return 0 ;
  }
  