Diff: RdDS18B20.cpp

Revision:

8:5980547ae71c

Child:

9:0e103c2f869a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/RdDS18B20.cpp	Sat Feb 21 19:00:08 2015 +0000
@@ -0,0 +1,143 @@
+// Handles OneWire temperature sensors DB18S20
+// Can handle multiple devices per pin
+// Rob Dobson, 2015
+
+#include "RdDS18B20.h"
+
+// #define SHOW_18B20_DEBUGGING 1
+
+// Construct onewire bus with desired pin
+DS18B20::DS18B20(PinName mbedPin) : _oneWire(mbedPin)
+{
+    _numValidAddresses = 0;
+}
+
+// Request conversion
+void DS18B20::ReqConvert()
+{
+    // Request conversion begins
+    _oneWire.init();
+    _oneWire.writeByte(0xCC);
+    _oneWire.writeByte(0x44);
+}
+
+// Get temperature
+double DS18B20::GetTemperature(int addrIdx)
+{
+    // Check valid address
+    if ((addrIdx >= _numValidAddresses) || (addrIdx < 0))
+        return -1000.0;
+    
+    // Init the bus and req reading
+    _oneWire.init();
+    _oneWire.writeByte(0x55);
+    
+    // Send the address
+    for (int i = 0; i < 8; i++)
+        _oneWire.writeByte(_addrTable[addrIdx][i]);
+    _oneWire.writeByte(0xBE);
+
+    // Temperature val
+    int temperatureVals[] = {0,0};
+
+    // Read values back
+    for (int i = 0; i < sizeof(temperatureVals)/sizeof(int); i++)
+    {
+        temperatureVals[i] = _oneWire.readByte();
+    }
+    _oneWire.init();
+    
+    // Convert temperature
+    double temperature = ((temperatureVals[1] * 256) + temperatureVals[0])*0.0625;
+    return temperature; 
+}
+
+// Get address for a device
+uint8_t* DS18B20::GetAddress(int addrIdx)
+{
+    if ((addrIdx >= _numValidAddresses) || (addrIdx < 0))
+        return _addrTable[0];
+    return _addrTable[addrIdx];
+}
+
+// Get address as a string
+char* DS18B20::GetAddressStr(int addrIdx)
+{
+    if ((addrIdx >= _numValidAddresses) || (addrIdx < 0))
+        return "";
+    sprintf(_addrStr, "%02x %02x %02x %02x %02x %02x %02x %02x", 
+        _addrTable[addrIdx][0], _addrTable[addrIdx][1], _addrTable[addrIdx][2], 
+        _addrTable[addrIdx][3], _addrTable[addrIdx][4], _addrTable[addrIdx][5], 
+        _addrTable[addrIdx][6], _addrTable[addrIdx][7]);
+    return _addrStr;
+}
+    
+// Debug print address
+void DS18B20::DebugPrintAddress(int addrIdx)
+{
+    // Check valid address
+    if ((addrIdx >= _numValidAddresses) || (addrIdx < 0))
+    {
+        printf("Invalid addrIdx %d", addrIdx);
+        return;
+    }
+    // Write out address
+    printf(GetAddressStr(addrIdx));
+}
+
+void DS18B20::SearchToGetAddresses()
+{
+    _numValidAddresses = 0;
+    for (int addrIdx = 0; addrIdx < MAX_BUS_DEVICES; addrIdx++)
+    {
+        uint8_t addr[8];
+
+        if ( !_oneWire.search(addr))
+        {
+#ifdef SHOW_18B20_DEBUGGING
+            printf("No more addresses.\r\n");
+#endif
+            _oneWire.reset_search();
+            break;
+        }
+        
+#ifdef SHOW_18B20_DEBUGGING
+        printf("Found device addr (ROM) =");
+#endif
+        for( int i = 0; i < 8; i++) 
+        {
+            // Copy to table
+            _addrTable[_numValidAddresses][i] = addr[i];
+#ifdef SHOW_18B20_DEBUGGING
+            printf(" %02x", addr[i]);
+#endif
+        }
+        
+        // Check CRC - only include if CRC is valid
+        if (_oneWire.CRC(addr, ONEWIRE_ADDR_BYTES-1) == addr[ONEWIRE_ADDR_BYTES-1])
+            _numValidAddresses++;
+#ifdef SHOW_18B20_DEBUGGING
+        else
+            printf(" (CRC INVALID!)");
+#endif
+
+#ifdef SHOW_18B20_DEBUGGING        
+        // the first ROM byte indicates which chip
+        switch (addr[0])
+        {
+            case 0x10:
+                printf("  Chip = DS18S20\r\n");  // or old DS1820
+                break;
+            case 0x28:
+                printf("  Chip = DS18B20\r\n");
+                break;
+            case 0x22:
+                printf("  Chip = DS1822\r\n");
+                break;
+            default:
+                printf("  NOT DS18x20 FAMILY\r\n");
+                break;
+        } 
+#endif
+    }  
+}