initial cleanup and mapping

wiringPi/sr595.c

@@ -0,0 +1,109 @@
+/*
+ * sr595.c:
+ *	Extend wiringPi with the 74x595 shift register as a GPIO
+ *	expander chip.
+ *	Note that the code can cope with a number of 595's
+ *	daisy-chained together - up to 4 for now as we're storing
+ *	the output "register" in a single unsigned int.
+ *
+ *	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 <stdint.h>
+
+#include "wiringPi.h"
+
+#include "sr595.h"
+
+
+/*
+ * myDigitalWrite:
+ *********************************************************************************
+ */
+
+static void myDigitalWrite (struct wiringPiNodeStruct *node, int pin, int value)
+{
+  unsigned int mask ;
+  int  dataPin, clockPin, latchPin ;
+  int  bit, bits, output ;
+
+  pin     -= node->pinBase ;				// Normalise pin number
+  bits     = node->pinMax - node->pinBase + 1 ;		// ie. number of clock pulses
+  dataPin  = node->data0 ;
+  clockPin = node->data1 ;
+  latchPin = node->data2 ;
+  output   = node->data3 ;
+
+  mask = 1 << pin ;
+
+  if (value == LOW)
+    output &= (~mask) ;
+  else
+    output |=   mask ;
+
+  node->data3 = output ;
+
+// A low -> high latch transition copies the latch to the output pins
+
+  digitalWrite (latchPin, LOW) ; delayMicroseconds (1) ;
+    for (bit = bits - 1 ; bit >= 0 ; --bit)
+    {
+      digitalWrite (dataPin, output & (1 << bit)) ;
+
+      digitalWrite (clockPin, HIGH) ; delayMicroseconds (1) ;
+      digitalWrite (clockPin, LOW) ;  delayMicroseconds (1) ;
+    }
+  digitalWrite (latchPin, HIGH) ; delayMicroseconds (1) ;
+}
+
+
+/*
+ * sr595Setup:
+ *	Create a new instance of a 74x595 shift register GPIO expander.
+ *********************************************************************************
+ */
+
+int sr595Setup (const int pinBase, const int numPins,
+	const int dataPin, const int clockPin, const int latchPin) 
+{
+  struct wiringPiNodeStruct *node ;
+
+  node = wiringPiNewNode (pinBase, numPins) ;
+
+  node->data0           = dataPin ;
+  node->data1           = clockPin ;
+  node->data2           = latchPin ;
+  node->data3           = 0 ;		// Output register
+  node->digitalWrite    = myDigitalWrite ;
+
+// Initialise the underlying hardware
+
+  digitalWrite (dataPin,  LOW) ;
+  digitalWrite (clockPin, LOW) ;
+  digitalWrite (latchPin, HIGH) ;
+
+  pinMode (dataPin,  OUTPUT) ;
+  pinMode (clockPin, OUTPUT) ;
+  pinMode (latchPin, OUTPUT) ;
+
+  return 0 ;
+}