Diff: readDS1920.cpp

Revision:

0:1193dbfe28e2

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/readDS1920.cpp	Thu Mar 24 17:21:29 2011 +0000
@@ -0,0 +1,133 @@
+//---------------------------------------------------------------------------
+// Copyright (C) 2000 Dallas Semiconductor Corporation, All Rights Reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY,  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL DALLAS SEMICONDUCTOR BE LIABLE FOR ANY CLAIM, DAMAGES
+// OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+//
+// Except as contained in this notice, the name of Dallas Semiconductor
+// shall not be used except as stated in the Dallas Semiconductor
+// Branding Policy.
+// ---------------------------------------------------------------------------
+//
+//  temp10.C - Module to read the DS1920/DS1820 - temperature measurement.
+//
+//  Version: 2.00
+//
+// ---------------------------------------------------------------------------
+//
+//
+#include "mbed.h"
+#include "ownet.h"
+#include "./Headers/readDS1920.h"
+
+//----------------------------------------------------------------------
+// Read the temperature of a DS1920/DS1820
+//
+// 'portnum'     - number 0 to MAX_PORTNUM-1.  This number was provided to
+//                 OpenCOM to indicate the port number.
+// 'SerialNum'   - Serial Number of DS1920/DS1820 to read temperature from
+// 'Temp '       - pointer to variable where that temperature will be
+//                 returned
+//
+// Returns: TRUE(1)  temperature has been read and verified
+//          FALSE(0) could not read the temperature, perhaps device is not
+//                   in contact
+//
+
+
+int ReadTemperature(int portnum, uchar *SerialNum, float *Temp)
+{
+   uchar rt=FALSE;
+   uchar send_block[30],lastcrc8;
+   int send_cnt, tsht, i, loop=0;
+   float tmp,cr,cpc;
+
+   // set the device serial number to the counter device
+   owSerialNum(portnum,SerialNum,FALSE);
+
+   for (loop = 0; loop < 2; loop ++)
+   {
+      // access the device
+      if (owAccess(portnum))
+      {
+         // send the convert command and start power delivery
+         if (!owWriteBytePower(portnum,0x44))
+            return FALSE;
+
+         // sleep for 1 second
+         msDelay(1000);
+
+         // turn off the 1-Wire Net strong pull-up
+         if (owLevel(portnum,MODE_NORMAL) != MODE_NORMAL)
+            return FALSE;
+
+         // access the device
+         if (owAccess(portnum))
+         {
+            // create a block to send that reads the temperature
+            // read scratchpad command
+            send_cnt = 0;
+            send_block[send_cnt++] = 0xBE;
+            // now add the read bytes for data bytes and crc8
+            for (i = 0; i < 9; i++)
+               send_block[send_cnt++] = 0xFF;
+
+            // now send the block
+            if (owBlock(portnum,FALSE,send_block,send_cnt))
+            {
+               // initialize the CRC8
+               setcrc8(portnum,0);
+               // perform the CRC8 on the last 8 bytes of packet
+               for (i = send_cnt - 9; i < send_cnt; i++)
+                  lastcrc8 = docrc8(portnum,send_block[i]);
+
+               // verify CRC8 is correct
+               if (lastcrc8 == 0x00)
+               {
+                  // calculate the high-res temperature
+                  tsht = send_block[1]/2;
+                  printf ("t1: %2x\r\n", tsht);
+                  if (send_block[2] & 0x01)
+                     tsht |= -128;
+                  printf ("t2: %2x\r\n", tsht);
+                  tmp = (float)(tsht);
+                  printf ("t3: %f\r\n", tmp);
+                  cr = send_block[7];
+                  cpc = send_block[8];
+                  if (((cpc - cr) == 1) && (loop == 0))
+                     continue;
+                  if (cpc == 0)
+                     return FALSE;
+                  else
+                     printf ("t4: %f\r\n", tmp);
+                     tmp = tmp - (float)0.25 + (cpc - cr)/cpc;
+                     printf ("t5: %f\r\n", tmp);
+                  *Temp = tmp;
+                  // success
+                  rt = TRUE;
+                  break;
+               }
+            }
+         }
+      }
+
+   }
+
+   // return the result flag rt
+   return rt;
+}