Diff: readDS18B20.cpp

Revision:

0:1193dbfe28e2

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/readDS18B20.cpp	Thu Mar 24 17:21:29 2011 +0000
@@ -0,0 +1,108 @@
+//---------------------------------------------------------------------------
+// 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 ReadDS18B20(int portnum, uchar *SerialNum, float *Temp)
+{
+    uchar rt=FALSE;
+    uchar send_block[30],lastcrc8;
+    int send_cnt, tsht, i;
+    float tmp;
+
+    // set the device serial number to the counter device
+    owSerialNum(portnum,SerialNum,FALSE);
+
+    // 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[2]*256 + send_block[1];
+                    tmp = (float)(tsht);
+                    tmp = tmp / 16;
+                    *Temp = tmp;
+                    // success
+                    rt = TRUE;
+                }
+            }
+        }
+    }
+    // return the result flag rt
+    return rt;
+}
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