Revision 7:aceafdd78b28, committed 2014-10-30

Comitter:

uci1

Date:

Thu Oct 30 05:55:15 2014 +0000

Parent:

6:c78fb487c397

Child:

8:7f64569563ea

Commit message:

allow use of parasite power to be switched on and off

Changed in this revision

--- a/DS1820.cpp	Mon Sep 22 00:38:39 2014 +0000
+++ b/DS1820.cpp	Thu Oct 30 05:55:15 2014 +0000
@@ -7,17 +7,20 @@
 char DS1820_search_ROM[8];
  
  
-DS1820::DS1820 (PinName data_pin, PinName power_pin) : _datapin(data_pin), _parasitepin(power_pin) {
+DS1820::DS1820 (PinName data_pin, PinName power_pin, const bool useParasitePwr) : 
+            _parasite_power(useParasitePwr),
+            _parasite_power_pn(power_pin),
+            _datapin(data_pin), _parasitepin(power_pin) {
     int byte_counter;
-    _parasite_power = true;
     for(byte_counter=0;byte_counter<8;byte_counter++)
         ROM[byte_counter] = 0xFF;
     for(byte_counter=0;byte_counter<9;byte_counter++)
         RAM[byte_counter] = 0x00;
 }
-DS1820::DS1820 (PinName data_pin) : _datapin(data_pin), _parasitepin(NC) {
+DS1820::DS1820 (PinName data_pin) : _parasite_power(false),
+                                    _parasite_power_pn(NC),
+                                    _datapin(data_pin), _parasitepin(NC) {
     int byte_counter;
-    _parasite_power = false;
     for(byte_counter=0;byte_counter<8;byte_counter++)
         ROM[byte_counter] = 0xFF;
     for(byte_counter=0;byte_counter<9;byte_counter++)
@@ -164,6 +167,7 @@
 }
  
 void DS1820::search_ROM_setup() {
+    _datapin.mode(PullUp);
     extern bool DS1820_done_flag;
     extern int DS1820_last_descrepancy;
     extern char DS1820_search_ROM[8];
@@ -250,6 +254,7 @@
 }
  
 int DS1820::convert_temperature(bool wait, devices device) {
+    _datapin.mode(PullUp);
     // Convert temperature into scratchpad RAM for all devices at once
     int delay_time = 750; // Default delay time
     char resolution;
@@ -371,6 +376,7 @@
 // this allowed an expanded resolution of 1/150th of a deg C. I wouldn't rely on this
 // being super acurate, but it does allow for a smooth display in the 1/10ths of a
 // deg C or F scales.
+    _datapin.mode(PullUp);
     float answer, remaining_count, count_per_degree;
     int reading;
     read_RAM();

--- a/DS1820.h	Mon Sep 22 00:38:39 2014 +0000
+++ b/DS1820.h	Thu Oct 30 05:55:15 2014 +0000
@@ -89,7 +89,8 @@
      * @param data_pin DigitalInOut pin for the data bus
      * @param power_pin DigitalOut pin to control the power MOSFET
      */
-    DS1820(PinName data_pin, PinName power_pin); // Constructor with parasite power pin
+    DS1820(PinName data_pin, PinName power_pin, 
+           const bool useParasitePwr=true); // Constructor with parasite power pin
 
     /** Create a probe object connected to the specified pin
      *  this is used when all probes are externally powered
@@ -247,21 +248,6 @@
       * returns false if the device (or ANY device) is parasite powered.
       */
     bool read_power_supply(devices device=this_device);
-
-    /** Allow the parasite pin to be set at any time. If it is set
-      * to "NC", then parasite mode is turned off. It is ok if this
-      * pin is the same as the datapin.
-      *
-      * @param parasitePin The pin to use for parasite power, or NC for
-      *        external power
-      * @returns true if the parasite power is set to a connected pin
-      *          false if parasite power is not connected (external power)
-      */
-    bool set_parasite_pin(DigitalInOut parasitePin) {
-        _parasitepin = parasitePin;
-        _parasite_power = (NC!=parasitePin);
-        return _parasite_power;
-    }
     
     /** Check if parasite power is being used.
       *
@@ -270,8 +256,26 @@
       */
     bool is_on_parasite_power() const { return _parasite_power; }
     
+    /** Allow use of parasite power to be switched on or off
+      *
+      * @param pwr Specify whether to use the parasite pin for power (true)
+      *            or not (false).
+      * @return true if using parasite power
+      *         false if not (i.e. parasite mode requested, but no parasite pin)
+      */
+    bool set_use_parasite_power(const bool pwr) {
+        if (pwr && (_parasite_power_pn!=NC)) {
+            _parasite_power = true;
+        } else {
+            _parasite_power = false;
+        }
+        return _parasite_power;
+    }
+    
 private:
     bool _parasite_power;
+    PinName _parasite_power_pn;
+    
     char CRC_byte (char CRC, char byte );
     bool onewire_reset();
     void match_ROM();