restructured

FlippR-Driver/lib/wiringPi/max31855.c

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+/*
+ * max31855.c:
+ *	Extend wiringPi with the max31855 SPI Analog to Digital convertor
+ *	Copyright (c) 2012-2015 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 <byteswap.h>
+#include <stdint.h>
+
+#include <wiringPi.h>
+#include <wiringPiSPI.h>
+
+#include "max31855.h"
+
+static int myAnalogRead (struct wiringPiNodeStruct *node, int pin)
+{
+  uint32_t spiData ;
+  int temp ;
+  int chan = pin - node->pinBase ;
+
+  wiringPiSPIDataRW (node->fd, (unsigned char *)&spiData, 4) ;
+
+  spiData = __bswap_32(spiData) ;
+
+  switch (chan)
+  {
+    case 0:				// Existing read - return raw value * 4
+      spiData >>= 18 ;
+      temp = spiData & 0x1FFF ;		// Bottom 13 bits
+      if ((spiData & 0x2000) != 0)	// Negative
+        temp = -temp ;
+
+      return temp ;
+
+    case 1:				// Return error bits
+      return spiData & 0x7 ;
+
+    case 2:				// Return temp in C * 10
+      spiData >>= 18 ;
+      temp = spiData & 0x1FFF ;		// Bottom 13 bits
+      if ((spiData & 0x2000) != 0)	// Negative
+        temp = -temp ;
+
+      return (int)((((double)temp * 25) + 0.5) / 10.0) ;
+
+    case 3:				// Return temp in F * 10
+      spiData >>= 18 ;
+      temp = spiData & 0x1FFF ;		// Bottom 13 bits
+      if ((spiData & 0x2000) != 0)	// Negative
+        temp = -temp ;
+
+      return (int)((((((double)temp * 0.25 * 9.0 / 5.0) + 32.0) * 100.0) + 0.5) / 10.0) ;
+
+    default:				// Who knows...
+      return 0 ;
+
+  }
+}
+
+
+/*
+ * max31855Setup:
+ *	Create a new wiringPi device node for an max31855 on the Pi's
+ *	SPI interface.
+ *********************************************************************************
+ */
+
+int max31855Setup (const int pinBase, int spiChannel)
+{
+  struct wiringPiNodeStruct *node ;
+
+  if (wiringPiSPISetup (spiChannel, 5000000) < 0)	// 5MHz - prob 4 on the Pi
+    return FALSE ;
+
+  node = wiringPiNewNode (pinBase, 4) ;
+
+  node->fd         = spiChannel ;
+  node->analogRead = myAnalogRead ;
+
+  return TRUE ;
+}