initial cleanup and mapping

devLib/maxdetect.c

@@ -0,0 +1,165 @@
+/*
+ * maxdetect.c:
+ *	Driver for the MaxDetect series sensors
+ *
+ * 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 <stdlib.h>
+//#include <unistd.h>
+
+#include <wiringPi.h>
+
+#include "maxdetect.h"
+
+#ifndef	TRUE
+#  define	TRUE	(1==1)
+#  define	FALSE	(1==2)
+#endif
+
+
+/*
+ * maxDetectLowHighWait:
+ *	Wait for a transition from high to low on the bus
+ *********************************************************************************
+ */
+
+static void maxDetectLowHighWait (const int pin)
+{
+  unsigned int timeOut = millis () + 2000 ;
+
+  while (digitalRead (pin) == HIGH)
+    if (millis () > timeOut)
+      return ;
+
+  while (digitalRead (pin) == LOW)
+    if (millis () > timeOut)
+      return ;
+}
+
+
+/*
+ * maxDetectClockByte:
+ *	Read in a single byte from the MaxDetect bus
+ *********************************************************************************
+ */
+
+static unsigned int maxDetectClockByte (const int pin)
+{
+  unsigned int byte = 0 ;
+  int bit ;
+
+  for (bit = 0 ; bit < 8 ; ++bit)
+  {
+    maxDetectLowHighWait (pin) ;
+
+// bit starting now - we need to time it.
+
+    delayMicroseconds (30) ;
+    byte <<= 1 ;
+    if (digitalRead (pin) == HIGH)	// It's a 1
+      byte |= 1 ;
+  }
+
+  return byte ;
+}
+
+
+/*
+ * maxDetectRead:
+ *	Read in and return the 4 data bytes from the MaxDetect sensor.
+ *	Return TRUE/FALSE depending on the checksum validity
+ *********************************************************************************
+ */
+
+int maxDetectRead (const int pin, unsigned char buffer [4])
+{
+  int i ;
+  unsigned int checksum ;
+  unsigned char localBuf [5] ;
+
+// Wake up the RHT03 by pulling the data line low, then high
+//	Low for 10mS, high for 40uS.
+
+  pinMode      (pin, OUTPUT) ;
+  digitalWrite (pin, 0) ; delay             (10) ;
+  digitalWrite (pin, 1) ; delayMicroseconds (40) ;
+  pinMode      (pin, INPUT) ;
+
+// Now wait for sensor to pull pin low
+
+  maxDetectLowHighWait (pin) ;
+
+// and read in 5 bytes (40 bits)
+
+  for (i = 0 ; i < 5 ; ++i)
+    localBuf [i] = maxDetectClockByte (pin) ;
+
+  checksum = 0 ;
+  for (i = 0 ; i < 4 ; ++i)
+  {
+    buffer [i] = localBuf [i] ;
+    checksum += localBuf [i] ;
+  }
+  checksum &= 0xFF ;
+
+  return checksum == localBuf [4] ;
+}
+
+
+/*
+ * readRHT03:
+ *	Read the Temperature & Humidity from an RHT03 sensor
+ *********************************************************************************
+ */
+
+int readRHT03 (const int pin, int *temp, int *rh)
+{
+  static unsigned int nextTime   = 0 ;
+  static          int lastTemp   = 0 ;
+  static          int lastRh     = 0 ;
+  static          int lastResult = TRUE ;
+
+  unsigned char buffer [4] ;
+
+// Don't read more than once a second
+
+  if (millis () < nextTime)
+  {
+    *temp = lastTemp ;
+    *rh   = lastRh ;
+    return lastResult ;
+  }
+  
+  lastResult = maxDetectRead (pin, buffer) ;
+
+  if (lastResult)
+  {
+    *temp      = lastTemp   = (buffer [2] * 256 + buffer [3]) ;
+    *rh        = lastRh     = (buffer [0] * 256 + buffer [1]) ;
+    nextTime   = millis () + 2000 ;
+    return TRUE ;
+  }
+  else
+  {
+    return FALSE ;
+  }
+}