Merge commit '474f163b53d438955dae1a0cc9d7df46344b3950' as 'Code/devterm_wiringpi_cpi'

Code/devterm_wiringpi_cpi/devLib/maxdetect.c

@@ -0,0 +1,238 @@
+/*
+ * 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 <sys/time.h>
+#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 low to high on the bus
+ *********************************************************************************
+ */
+
+static int maxDetectLowHighWait (const int pin)
+{
+  struct timeval now, timeOut, timeUp ;
+
+// If already high then wait for pin to go low
+
+  gettimeofday (&now, NULL) ;
+  timerclear   (&timeOut) ;
+  timeOut.tv_usec = 1000 ;
+  timeradd     (&now, &timeOut, &timeUp) ;
+
+  while (digitalRead (pin) == HIGH)
+  {
+    gettimeofday (&now, NULL) ;
+    if (timercmp (&now, &timeUp, >))
+      return FALSE ;
+  }
+
+// Wait for it to go HIGH
+
+  gettimeofday (&now, NULL) ;
+  timerclear (&timeOut) ;
+  timeOut.tv_usec = 1000 ;
+  timeradd (&now, &timeOut, &timeUp) ;
+
+  while (digitalRead (pin) == LOW)
+  {
+    gettimeofday (&now, NULL) ;
+    if (timercmp (&now, &timeUp, >))
+      return FALSE ;
+  }
+
+  return TRUE ;
+}
+
+
+/*
+ * 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)
+  {
+    if (!maxDetectLowHighWait (pin))
+      return 0 ;
+
+// 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] ;
+  struct timeval now, then, took ;
+
+// See how long we took
+
+  gettimeofday (&then, NULL) ;
+
+// 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
+
+  if (!maxDetectLowHighWait (pin))
+    return FALSE ;
+
+// 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 ;
+
+// See how long we took
+  
+  gettimeofday (&now, NULL) ;
+  timersub (&now, &then, &took) ;
+
+// Total time to do this should be:
+//	10mS + 40µS - reset
+//	+ 80µS + 80µS - sensor doing its low -> high thing
+//	+ 40 * (50µS + 27µS (0) or 70µS (1) )
+//	= 15010µS
+// so if we take more than that, we've had a scheduling interruption and the
+// reading is probably bogus.
+
+  if ((took.tv_sec != 0) || (took.tv_usec > 16000))
+    return FALSE ;
+
+  return checksum == localBuf [4] ;
+}
+
+
+/*
+ * readRHT03:
+ *	Read the Temperature & Humidity from an RHT03 sensor
+ *	Values returned are *10, so 123 is 12.3.
+ *********************************************************************************
+ */
+
+int readRHT03 (const int pin, int *temp, int *rh)
+{
+  static struct timeval then ;	// will initialise to zero
+  static        int     lastTemp = 0 ;
+  static        int     lastRh   = 0 ;
+
+  int result ;
+  struct timeval now, timeOut ;
+  unsigned char buffer [4] ;
+
+// The data sheets say to not read more than once every 2 seconds, so you
+//	get the last good reading
+
+  gettimeofday (&now, NULL) ;
+  if (timercmp (&now, &then, <))
+  {
+    *rh   = lastRh ;
+    *temp = lastTemp ;
+    return TRUE ;
+  }
+
+// Set timeout for next read
+
+  gettimeofday (&now, NULL) ;
+  timerclear   (&timeOut) ;
+  timeOut.tv_sec = 2 ;
+  timeradd (&now, &timeOut, &then) ;
+
+// Read ...
+  
+  result = maxDetectRead (pin, buffer) ;
+
+  if (!result) // Try again, but just once
+    result = maxDetectRead (pin, buffer) ;
+
+  if (!result)
+    return FALSE ;
+
+  *rh   = (buffer [0] * 256 + buffer [1]) ;
+  *temp = (buffer [2] * 256 + buffer [3]) ;
+
+  if ((*temp & 0x8000) != 0)	// Negative
+  {
+    *temp &= 0x7FFF ;
+    *temp = -*temp ;
+  }
+
+// Discard obviously bogus readings - the checksum can't detect a 2-bit error
+//	(which does seem to happen - no realtime here)
+
+  if ((*rh > 999) || (*temp > 800) || (*temp < -400))
+    return FALSE ;
+
+  lastRh   = *rh ;
+  lastTemp = *temp ;
+
+  return TRUE ;
+}