initial cleanup and mapping

wiringPi/mcp4802.c

@@ -0,0 +1,76 @@
+/*
+ * mcp4802.c:
+ *	Extend wiringPi with the MCP4802 SPI Digital to Analog convertor
+ *	Copyright (c) 2012-2013 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 <wiringPi.h>
+#include <wiringPiSPI.h>
+
+#include "mcp4802.h"
+
+/*
+ * myAnalogWrite:
+ *	Write analog value on the given pin
+ *********************************************************************************
+ */
+
+static void myAnalogWrite (struct wiringPiNodeStruct *node, int pin, int value)
+{
+  unsigned char spiData [2] ;
+  unsigned char chanBits, dataBits ;
+  int chan = pin - node->pinBase ;
+
+  if (chan == 0)
+    chanBits = 0x30 ;
+  else
+    chanBits = 0xB0 ;
+
+  chanBits |= ((value >> 4) & 0x0F) ;
+  dataBits  = ((value << 4) & 0xF0) ;
+
+  spiData [0] = chanBits ;
+  spiData [1] = dataBits ;
+
+  wiringPiSPIDataRW (node->fd, spiData, 2) ;
+}
+
+/*
+ * mcp4802Setup:
+ *	Create a new wiringPi device node for an mcp4802 on the Pi's
+ *	SPI interface.
+ *********************************************************************************
+ */
+
+int mcp4802Setup (const int pinBase, int spiChannel)
+{
+  struct wiringPiNodeStruct *node ;
+
+  if (wiringPiSPISetup (spiChannel, 1000000) < 0)
+    return -1 ;
+
+  node = wiringPiNewNode (pinBase, 2) ;
+
+  node->fd          = spiChannel ;
+  node->analogWrite = myAnalogWrite ;
+
+  return 0 ;
+}