mcp3004.c
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/*
* mcp3004.c:
* Extend wiringPi with the MCP3004 SPI Analog to Digital convertor
* Copyright (c) 2012-2013 Gordon Henderson
*
* Thanks also to "ShorTie" on IRC for some remote debugging help!
***********************************************************************
* 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 "mcp3004.h"
/*
* myAnalogRead:
* Return the analog value of the given pin
*********************************************************************************
*/
static int myAnalogRead (struct wiringPiNodeStruct *node, int pin)
{
unsigned char spiData [3] ;
unsigned char chanBits ;
int chan = pin - node->pinBase ;
chanBits = 0b10000000 | (chan << 4) ;
spiData [0] = 1 ; // Start bit
spiData [1] = chanBits ;
spiData [2] = 0 ;
wiringPiSPIDataRW (node->fd, spiData, 3) ;
return ((spiData [1] << 8) | spiData [2]) & 0x3FF ;
}
/*
* mcp3004Setup:
* Create a new wiringPi device node for an mcp3004 on the Pi's
* SPI interface.
*********************************************************************************
*/
int mcp3004Setup (const int pinBase, int spiChannel)
{
struct wiringPiNodeStruct *node ;
if (wiringPiSPISetup (spiChannel, 1000000) < 0)
return -1 ;
node = wiringPiNewNode (pinBase, 8) ;
node->fd = spiChannel ;
node->analogRead = myAnalogRead ;
return 0 ;
}