Diff: DS1820.h

Revision:

0:61d83318f2d6

Child:

1:6a427f54e82c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/DS1820.h	Sun Dec 19 05:40:28 2010 +0000
@@ -0,0 +1,252 @@
+/* mbed DS1820 Library, for the Dallas (Maxim) 1-Wire Digital Thermometer
+ * Copyright (c) 2010, Michael Hagberg Michael@RedBoxCode.com
+ *
+ * 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 THE
+ * AUTHORS OR COPYRIGHT HOLDERS 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.
+ */
+
+#ifndef MBED_DS1820_H
+#define MBED_DS1820_H
+
+#include "mbed.h"
+
+// ****** THIS GLOBAL VARIABLES MUST BE DEFINED IN main.cpp
+
+// Global variables shared between all DS1820 objects
+//bool DS1820_done_flag;
+//int  DS1820_last_descrepancy;
+//char DS1820_search_ROM[8];
+
+/** DS1820 Dallas 1-Wire Temperature Probe
+ *
+ * Example:
+ * @code
+ * #include "mbed.h"
+ *
+ * #include "TextLCD.h"
+ * #include "DS1820.h"
+ *
+ * TextLCD lcd(p25, p26, p21, p22, p23, p24, TextLCD::LCD16x2); // rs, e, d0-d3, layout
+ *
+ * const int MAX_PROBES = 16;
+ * DS1820* probe[MAX_PROBES];
+ *
+ * int main() {
+ *     int i;
+ *     int devices_found=0;
+ *     // Initialize the probe array to DS1820 objects
+ *     for (i = 0; i < MAX_PROBES; i++)
+ *         probe[i] = new DS1820(p27);
+ *     // Initialize global state variables
+ *     probe[0]->search_ROM_setup();
+ *     // Loop to find all devices on the data line
+ *     while (probe[devices_found]->search_ROM() and devices_found<MAX_PROBES-1)
+ *         devices_found++;
+ *     // If maximum number of probes are found, 
+ *     // bump the counter to include the last array entry
+ *     if (probe[devices_found]->ROM[0] != 0xFF)
+ *         devices_found++;
+ * 
+ *     lcd.cls();
+ *     if (devices_found==0)
+ *         lcd.printf("No devices found");
+ *     else {
+ *         while (true) {
+ *             probe[0]->convert_temperature(DS1820::all_devices);
+ *             lcd.cls();
+ *             for (i=0; i<devices_found; i++) {
+ *                 lcd.printf("%3.1f ",probe[i]->temperature('f'));
+ *             }
+ *         }
+ *     }
+ * }
+ * @endcode
+ */
+ 
+class DS1820 {
+public:
+    enum devices{
+        this_device,     // command applies to only this device
+        all_devices };   // command applies to all devices
+
+    /** Create a probe object connected to the specified pins
+     *
+     * @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
+
+    /** Create a probe object connected to the specified pin
+     *  this is used when all probes are externally powered
+     *
+     * @param data_pin DigitalInOut pin for the data bus
+     */
+    DS1820(PinName data_pin);
+
+    /** ROM is a copy of the internal DS1820's ROM
+      * It's created during the search_ROM() or search_alarm() commands
+      *
+      * ROM[0] is the Dallas Family Code
+      * ROM[1] thru ROM[6] is the 48-bit unique serial number
+      * ROM[7] is the device CRC
+      */
+    char ROM[8];
+    
+    /** RAM is a copy of the internal DS1820's RAM
+      * It's updated during the read_RAM() command
+      * which is automaticaly called from any function
+      * using the RAM values.
+      */
+    char RAM[9];
+    
+    /* This function copies the DS1820's RAM into the object's
+     * RAM[].
+     */
+    void read_RAM();
+
+    /** This routine initializes the global variables used in
+      * the search_ROM() and search_alarm() funtions. It should
+      * be called once before looping to find devices.
+      */
+    void search_ROM_setup();
+
+    /** This routine will search for an unidentified device
+      * on the bus. It uses the variables in search_ROM_setup
+      * to remember the pervious ROM address found.
+      * It will return FALSE if there were no new devices
+      * discovered on the bus.
+      */
+    bool search_ROM();
+
+    /** This routine will search for an unidentified device
+      * which has the temperature alarm bit set. It uses the 
+      * variables in search_ROM_setup to remember the pervious 
+      * ROM address found. It will return FALSE if there were 
+      * no new devices with alarms discovered on the bus.
+      */
+    bool search_alarm();
+
+    /** This routine will read the ROM (Family code, serial number
+      * and Checksum) from a dedicated device on the bus.
+      *
+      * NOTE: This command can only be used when there is only one 
+      *       DS1820 on the bus. If this command is used when there 
+      *       is more than one slave present on the bus, a data 
+      *       collision will occur when all the DS1820s attempt to 
+      *       respond at the same time.
+      */
+    void read_ROM();
+
+    /** This routine will initiate the temperature conversion within
+      * a DS1820. There is a built in 750ms delay to allow the 
+      * conversion to complete.
+      *
+      * To update all probes on the bus, use a statement such as this:
+      * probe[0]->convert_temperature(DS1820::all_devices);
+      *
+      * @param allows the fnction to apply to a specific device or
+      * to all devices on the 1-Wire bus.
+      */
+    void convert_temperature(devices device=this_device);
+
+    /** This function will return the probe temperature. This function
+      * uses the count remainding values to interpolate the temperature
+      * to about 1/150th of a degree. Whereas the probe is not spec to
+      * that precision. It does seem to give a smooth reading to the
+      * tenth of a degree.
+      *
+      * @param scale, may be either 'c' or 'f'
+      * @returns temperature for that scale
+      */
+    float temperature(char scale='c');
+    
+    /** This function calculates the ROM checksum and compares it to the
+      * CRC value stored in ROM[7].
+      *
+      * @returns true if the checksum matches, otherwise false.
+      */
+    bool ROM_checksum_error();
+
+    /** This function calculates the RAM checksum and compares it to the
+      * CRC value stored in RAM[8].
+      *
+      * @returns true if the checksum matches, otherwise false.
+      */
+    bool RAM_checksum_error();
+
+    /** This funtion returns the values stored in the temperature
+      * alarm registers. 
+      *
+      * @returns a 16 bit integer of TH (upper byte) and TL (lower byte).
+      */
+    int read_scratchpad();
+    
+    /** This function will store the passed data into the DS1820's RAM.
+      * Note: It does NOT save the data to the EEPROM for retention
+      * during cycling the power off and on.
+      *
+      * @param a 16 bit integer of TH (upper byte) and TL (lower byte).
+      */
+    void write_scratchpad(int data);
+    
+    /** This function will transfer the TH and TL registers from the
+      * DS1820's RAM into the EEPROM.
+      * Note: There is a built in 10ms delay to allow for the
+      * completion of the EEPROM write cycle.
+      *
+      * @param allows the fnction to apply to a specific device or
+      * to all devices on the 1-Wire bus.
+      */
+    void store_scratchpad(devices device=this_device);
+
+    /** This function will copy the stored values from the EEPROM
+      * into the DS1820's RAM locations for TH and TL.
+      *
+      * @param allows the fnction to apply to a specific device or
+      * to all devices on the 1-Wire bus.
+      */
+    int recall_scratchpad(devices device=this_device);
+
+    /** This function will return the type of power supply for
+      * a specific device. It can also be used to query all devices
+      * looking for any device that is parasite powered.
+      *
+      * @returns true if the device (or all devices) are Vcc powered,
+      * returns false if the device (or ANY device) is parasite powered.
+      */
+    bool read_power_supply(devices device=this_device);
+
+private:
+    bool _parasite_power;
+    char CRC_byte (char CRC, char byte );
+    bool onewire_reset();
+    void match_ROM();
+    void skip_ROM();
+    bool search_ROM_routine(char command);
+    void onewire_bit_out (bool bit_data);
+    void onewire_byte_out(char data);
+    bool onewire_bit_in();
+    char onewire_byte_in();
+
+protected:
+    DigitalInOut _datapin;
+    DigitalOut _parasitepin;
+};
+
+
+#endif