126 lines
3.3 KiB
C
126 lines
3.3 KiB
C
/*
|
|
* mcp3422.c:
|
|
* Extend wiringPi with the MCP3422/3/4 I2C ADC chip
|
|
* This code assumes single-ended mode only.
|
|
* Tested on actual hardware: 20th Feb 2016.
|
|
* Copyright (c) 2013-2016 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 <stdio.h>
|
|
#include <unistd.h>
|
|
#include <stdint.h>
|
|
#include <fcntl.h>
|
|
#include <sys/ioctl.h>
|
|
|
|
#include <wiringPi.h>
|
|
#include <wiringPiI2C.h>
|
|
|
|
#include "mcp3422.h"
|
|
|
|
|
|
/*
|
|
* waitForConversion:
|
|
* Common code to wait for the ADC to finish conversion
|
|
*********************************************************************************
|
|
*/
|
|
|
|
void waitForConversion (int fd, unsigned char *buffer, int n)
|
|
{
|
|
for (;;)
|
|
{
|
|
read (fd, buffer, n) ;
|
|
if ((buffer [n-1] & 0x80) == 0)
|
|
break ;
|
|
delay (1) ;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* myAnalogRead:
|
|
* Read a channel from the device
|
|
*********************************************************************************
|
|
*/
|
|
|
|
int myAnalogRead (struct wiringPiNodeStruct *node, int chan)
|
|
{
|
|
unsigned char config ;
|
|
unsigned char buffer [4] ;
|
|
int value = 0 ;
|
|
int realChan = (chan & 3) - node->pinBase ;
|
|
|
|
// One-shot mode, trigger plus the other configs.
|
|
|
|
config = 0x80 | (realChan << 5) | (node->data0 << 2) | (node->data1) ;
|
|
|
|
wiringPiI2CWrite (node->fd, config) ;
|
|
|
|
switch (node->data0) // Sample rate
|
|
{
|
|
case MCP3422_SR_3_75: // 18 bits
|
|
waitForConversion (node->fd, &buffer [0], 4) ;
|
|
value = ((buffer [0] & 3) << 16) | (buffer [1] << 8) | buffer [2] ;
|
|
break ;
|
|
|
|
case MCP3422_SR_15: // 16 bits
|
|
waitForConversion (node->fd, buffer, 3) ;
|
|
value = (buffer [0] << 8) | buffer [1] ;
|
|
break ;
|
|
|
|
case MCP3422_SR_60: // 14 bits
|
|
waitForConversion (node->fd, buffer, 3) ;
|
|
value = ((buffer [0] & 0x3F) << 8) | buffer [1] ;
|
|
break ;
|
|
|
|
case MCP3422_SR_240: // 12 bits - default
|
|
waitForConversion (node->fd, buffer, 3) ;
|
|
value = ((buffer [0] & 0x0F) << 8) | buffer [1] ;
|
|
break ;
|
|
}
|
|
|
|
return value ;
|
|
}
|
|
|
|
|
|
/*
|
|
* mcp3422Setup:
|
|
* Create a new wiringPi device node for the mcp3422
|
|
*********************************************************************************
|
|
*/
|
|
|
|
int mcp3422Setup (int pinBase, int i2cAddress, int sampleRate, int gain)
|
|
{
|
|
int fd ;
|
|
struct wiringPiNodeStruct *node ;
|
|
|
|
if ((fd = wiringPiI2CSetup (i2cAddress)) < 0)
|
|
return FALSE ;
|
|
|
|
node = wiringPiNewNode (pinBase, 4) ;
|
|
|
|
node->fd = fd ;
|
|
node->data0 = sampleRate ;
|
|
node->data1 = gain ;
|
|
node->analogRead = myAnalogRead ;
|
|
|
|
return TRUE ;
|
|
}
|