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95 lines
2.7 KiB
95 lines
2.7 KiB
/* |
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* pseudoPins.c: |
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* Extend wiringPi with a number of pseudo pins which can be |
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* digitally or analog written/read. |
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* |
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* Note: |
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* Just one set of pseudo pins can exist per Raspberry Pi. |
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* These pins are shared between all programs running on |
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* that Raspberry Pi. The values are also persistant as |
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* they live in shared RAM. This gives you a means for |
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* temporary variable storing/sharing between programs, |
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* or for other cunning things I've not thought of yet.. |
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* |
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* Copyright (c) 2012-2016 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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#define SHARED_NAME "wiringPiPseudoPins" |
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#define PSEUDO_PINS 64 |
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#include <unistd.h> |
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#include <sys/types.h> |
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#include <sys/mman.h> |
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#include <sys/stat.h> |
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#include <fcntl.h> |
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#include <wiringPi.h> |
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#include "pseudoPins.h" |
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static int myAnalogRead (struct wiringPiNodeStruct *node, int pin) |
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{ |
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int *ptr = (int *)node->data0 ; |
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int myPin = pin - node->pinBase ; |
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return *(ptr + myPin) ; |
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} |
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static void myAnalogWrite (struct wiringPiNodeStruct *node, int pin, int value) |
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{ |
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int *ptr = (int *)node->data0 ; |
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int myPin = pin - node->pinBase ; |
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*(ptr + myPin) = value ; |
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} |
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/* |
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* pseudoPinsSetup: |
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* Create a new wiringPi device node for the pseudoPins driver |
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********************************************************************************* |
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*/ |
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int pseudoPinsSetup (const int pinBase) |
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{ |
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struct wiringPiNodeStruct *node ; |
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void *ptr ; |
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node = wiringPiNewNode (pinBase, PSEUDO_PINS) ; |
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node->fd = shm_open (SHARED_NAME, O_CREAT | O_RDWR, 0666) ; |
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if (node->fd < 0) |
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return FALSE ; |
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if (ftruncate (node->fd, PSEUDO_PINS * sizeof (int)) < 0) |
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return FALSE ; |
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ptr = mmap (NULL, PSEUDO_PINS * sizeof (int), PROT_READ | PROT_WRITE, MAP_SHARED, node->fd, 0) ; |
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node->data0 = (unsigned int)ptr ; |
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node->analogRead = myAnalogRead ; |
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node->analogWrite = myAnalogWrite ; |
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return TRUE ; |
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}
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