You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
90 lines
2.5 KiB
90 lines
2.5 KiB
/* |
|
* pcf8591.c: |
|
* Extend wiringPi with the PCF8591 I2C GPIO Analog expander chip |
|
* The chip has 1 8-bit DAC and 4 x 8-bit ADCs |
|
* Copyright (c) 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 <unistd.h> |
|
|
|
#include "wiringPi.h" |
|
#include "wiringPiI2C.h" |
|
|
|
#include "pcf8591.h" |
|
|
|
|
|
/* |
|
* myAnalogWrite: |
|
********************************************************************************* |
|
*/ |
|
|
|
static void myAnalogWrite (struct wiringPiNodeStruct *node, UNU int pin, int value) |
|
{ |
|
unsigned char b [2] ; |
|
b [0] = 0x40 ; |
|
b [1] = value & 0xFF ; |
|
if ( write (node->fd, b, 2) ){;} |
|
|
|
} |
|
|
|
/* |
|
* myAnalogRead: |
|
********************************************************************************* |
|
*/ |
|
|
|
static int myAnalogRead (struct wiringPiNodeStruct *node, int pin) |
|
{ |
|
int x ; |
|
|
|
wiringPiI2CWrite (node->fd, 0x40 | ((pin - node->pinBase) & 3)) ; |
|
|
|
x = wiringPiI2CRead (node->fd) ; // Throw away the first read |
|
x = wiringPiI2CRead (node->fd) ; |
|
|
|
return x ; |
|
} |
|
|
|
|
|
/* |
|
* pcf8591Setup: |
|
* Create a new instance of a PCF8591 I2C GPIO interface. We know it |
|
* has 4 pins, (4 analog inputs and 1 analog output which we'll shadow |
|
* input 0) so all we need to know here is the I2C address and the |
|
* user-defined pin base. |
|
********************************************************************************* |
|
*/ |
|
|
|
int pcf8591Setup (const int pinBase, const int i2cAddress) |
|
{ |
|
int fd ; |
|
struct wiringPiNodeStruct *node ; |
|
|
|
if ((fd = wiringPiI2CSetup (i2cAddress)) < 0) |
|
return FALSE ; |
|
|
|
node = wiringPiNewNode (pinBase, 4) ; |
|
|
|
node->fd = fd ; |
|
node->analogRead = myAnalogRead ; |
|
node->analogWrite = myAnalogWrite ; |
|
|
|
return TRUE ; |
|
}
|
|
|