mirror of
https://github.com/clockworkpi/WiringPi.git
synced 2025-12-12 16:08:49 +01:00
b1dfc186ef
for kernels 4.8 onwards. Some very old stuff might break. Additional fixes for the ISR code and some tweaks here and there. I've removed the checks for some operations that might fail when using the gpiomem interface - which is now the default way of doing things - if your program segfaults, then you may need to use sudo on it.
147 lines
3.4 KiB
C
147 lines
3.4 KiB
C
/*
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* ds18b20.c:
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* Extend wiringPi with the DS18B20 1-Wire temperature sensor.
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* This is used in the Pi Weather Station and many other places.
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* Copyright (c) 2016 Gordon Henderson
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***********************************************************************
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* This file is part of wiringPi:
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* https://projects.drogon.net/raspberry-pi/wiringpi/
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*
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* wiringPi is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* wiringPi is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with wiringPi.
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* If not, see <http://www.gnu.org/licenses/>.
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***********************************************************************
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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#include <malloc.h>
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#include <ctype.h>
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#include "wiringPi.h"
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#include "ds18b20.h"
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#define W1_PREFIX "/sys/bus/w1/devices/28-"
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#define W1_POSTFIX "/w1_slave"
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/*
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* myAnalogRead:
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*********************************************************************************
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*/
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static int myAnalogRead (struct wiringPiNodeStruct *node, int pin)
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{
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int chan = pin - node->pinBase ;
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int fd = node->fd ;
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char buffer [4096] ;
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char *p ;
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int temp, sign ;
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if (chan != 0)
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return -9999 ;
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// Rewind the file - we're keeping it open to keep things going
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// smoothly
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lseek (fd, 0, SEEK_SET) ;
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// Read the file - we know it's only a couple of lines, so this ought to be
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// more than enough
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if (read (fd, buffer, 4096) <= 0) // Read nothing, or it failed in some odd way
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return -9998 ;
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// Look for YES, then t=
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if (strstr (buffer, "YES") == NULL)
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return -9997 ;
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if ((p = strstr (buffer, "t=")) == NULL)
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return -9996 ;
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// p points to the 't', so we skip over it...
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p += 2 ;
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// and extract the number
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// (without caring about overflow)
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if (*p == '-') // Negative number?
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{
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sign = -1 ;
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++p ;
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}
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else
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sign = 1 ;
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temp = 0 ;
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while (isdigit (*p))
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{
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temp = temp * 10 + (*p - '0') ;
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++p ;
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}
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// We know it returns temp * 1000, but we only really want temp * 10, so
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// do a bit of rounding...
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temp = (temp + 50) / 100 ;
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return temp * sign ;
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}
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/*
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* ds18b20Setup:
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* Create a new instance of a DS18B20 temperature sensor.
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*********************************************************************************
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*/
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int ds18b20Setup (const int pinBase, const char *deviceId)
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{
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int fd ;
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struct wiringPiNodeStruct *node ;
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char *fileName ;
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// Allocate space for the filename
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if ((fileName = malloc (strlen (W1_PREFIX) + strlen (W1_POSTFIX) + strlen (deviceId) + 1)) == NULL)
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return FALSE ;
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sprintf (fileName, "%s%s%s", W1_PREFIX, deviceId, W1_POSTFIX) ;
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fd = open (fileName, O_RDONLY) ;
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free (fileName) ;
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if (fd < 0)
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return FALSE ;
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// We'll keep the file open, to make access a little faster
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// although it's very slow reading these things anyway )-:
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node = wiringPiNewNode (pinBase, 1) ;
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node->fd = fd ;
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node->analogRead = myAnalogRead ;
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return TRUE ;
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}
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