initial cleanup and mapping

wiringPi/pcf8574.c

@@ -0,0 +1,126 @@
+/*
+ * pcf8574.c:
+ *	Extend wiringPi with the PCF8574 I2C GPIO expander chip
+ *	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 <stdio.h>
+#include <pthread.h>
+
+#include "wiringPi.h"
+#include "wiringPiI2C.h"
+
+#include "pcf8574.h"
+
+
+/*
+ * myPinMode:
+ *	The PCF8574 is an odd chip - the pins are effectively bi-directional,
+ *	however the pins should be drven high when used as an input pin...
+ *	So, we're effectively copying digitalWrite...
+ *********************************************************************************
+ */
+
+static void myPinMode (struct wiringPiNodeStruct *node, int pin, int mode)
+{
+  int bit, old ;
+
+  bit  = 1 << ((pin - node->pinBase) & 7) ;
+
+  old = node->data2 ;
+  if (mode == OUTPUT)
+    old &= (~bit) ;	// Write bit to 0
+  else
+    old |=   bit ;	// Write bit to 1
+
+  wiringPiI2CWrite (node->fd, old) ;
+  node->data2 = old ;
+}
+
+
+
+/*
+ * myDigitalWrite:
+ *********************************************************************************
+ */
+
+static void myDigitalWrite (struct wiringPiNodeStruct *node, int pin, int value)
+{
+  int bit, old ;
+
+  bit  = 1 << ((pin - node->pinBase) & 7) ;
+
+  old = node->data2 ;
+  if (value == LOW)
+    old &= (~bit) ;
+  else
+    old |=   bit ;
+
+  wiringPiI2CWrite (node->fd, old) ;
+  node->data2 = old ;
+}
+
+
+/*
+ * myDigitalRead:
+ *********************************************************************************
+ */
+
+static int myDigitalRead (struct wiringPiNodeStruct *node, int pin)
+{
+  int mask, value ;
+
+  mask  = 1 << ((pin - node->pinBase) & 7) ;
+  value = wiringPiI2CRead (node->fd) ;
+
+  if ((value & mask) == 0)
+    return LOW ;
+  else 
+    return HIGH ;
+}
+
+
+/*
+ * pcf8574Setup:
+ *	Create a new instance of a PCF8574 I2C GPIO interface. We know it
+ *	has 8 pins, so all we need to know here is the I2C address and the
+ *	user-defined pin base.
+ *********************************************************************************
+ */
+
+int pcf8574Setup (const int pinBase, const int i2cAddress)
+{
+  int fd ;
+  struct wiringPiNodeStruct *node ;
+
+  if ((fd = wiringPiI2CSetup (i2cAddress)) < 0)
+    return fd ;
+
+  node = wiringPiNewNode (pinBase, 8) ;
+
+  node->fd           = fd ;
+  node->pinMode      = myPinMode ;
+  node->digitalRead  = myDigitalRead ;
+  node->digitalWrite = myDigitalWrite ;
+  node->data2        = wiringPiI2CRead (fd) ;
+
+  return 0 ;
+}