DS18B20的分辨率怎么设置成 9, 10, 11位，默认是12位的

hi55234

先上DallasTemperature.h

1. #ifndef DallasTemperature_h
   
2. #define DallasTemperature_h
   
3. 
   
4. #define DALLASTEMPLIBVERSION "3.7.2"
   
5. 
   
6. // This library is free software; you can redistribute it and/or
   
7. // modify it under the terms of the GNU Lesser General Public
   
8. // License as published by the Free Software Foundation; either
   
9. // version 2.1 of the License, or (at your option) any later version.
   
10. 
    
11. // set to true to include code for new and delete operators
    
12. #ifndef REQUIRESNEW
    
13. #define REQUIRESNEW false
    
14. #endif
    
15. 
    
16. // set to true to include code implementing alarm search functions
    
17. #ifndef REQUIRESALARMS
    
18. #define REQUIRESALARMS true
    
19. #endif
    
20. 
    
21. #include <inttypes.h>
    
22. #include <OneWire.h>
    
23. 
    
24. // Model IDs
    
25. #define DS18S20MODEL 0x10
    
26. #define DS18B20MODEL 0x28
    
27. #define DS1822MODEL  0x22
    
28. 
    
29. // OneWire commands
    
30. #define STARTCONVO      0x44  // Tells device to take a temperature reading and put it on the scratchpad
    
31. #define COPYSCRATCH     0x48  // Copy EEPROM
    
32. #define READSCRATCH     0xBE  // Read EEPROM
    
33. #define WRITESCRATCH    0x4E  // Write to EEPROM
    
34. #define RECALLSCRATCH   0xB8  // Reload from last known
    
35. #define READPOWERSUPPLY 0xB4  // Determine if device needs parasite power
    
36. #define ALARMSEARCH     0xEC  // Query bus for devices with an alarm condition
    
37. 
    
38. // Scratchpad locations
    
39. #define TEMP_LSB        0
    
40. #define TEMP_MSB        1
    
41. #define HIGH_ALARM_TEMP 2
    
42. #define LOW_ALARM_TEMP  3
    
43. #define CONFIGURATION   4
    
44. #define INTERNAL_BYTE   5
    
45. #define COUNT_REMAIN    6
    
46. #define COUNT_PER_C     7
    
47. #define SCRATCHPAD_CRC  8
    
48. 
    
49. // Device resolution
    
50. #define TEMP_9_BIT  0x1F //  9 bit
    
51. #define TEMP_10_BIT 0x3F // 10 bit
    
52. #define TEMP_11_BIT 0x5F // 11 bit
    
53. #define TEMP_12_BIT 0x7F // 12 bit
    
54. 
    
55. // Error Codes
    
56. #define DEVICE_DISCONNECTED -127
    
57. 
    
58. typedef uint8_t DeviceAddress[8];
    
59. 
    
60. class DallasTemperature
    
61. {
    
62.   public:
    
63. 
    
64.   DallasTemperature(OneWire*);
    
65. 
    
66.   // initalise bus
    
67.   void begin(void);
    
68. 
    
69.   // returns the number of devices found on the bus
    
70.   uint8_t getDeviceCount(void);
    
71.   
    
72.   // Is a conversion complete on the wire?
    
73.   bool isConversionComplete(void);
    
74.   
    
75.   // returns true if address is valid
    
76.   bool validAddress(uint8_t*);
    
77. 
    
78.   // finds an address at a given index on the bus
    
79.   bool getAddress(uint8_t*, const uint8_t);
    
80.   
    
81.   // attempt to determine if the device at the given address is connected to the bus
    
82.   bool isConnected(uint8_t*);
    
83. 
    
84.   // attempt to determine if the device at the given address is connected to the bus
    
85.   // also allows for updating the read scratchpad
    
86.   bool isConnected(uint8_t*, uint8_t*);
    
87. 
    
88.   // read device's scratchpad
    
89.   void readScratchPad(uint8_t*, uint8_t*);
    
90. 
    
91.   // write device's scratchpad
    
92.   void writeScratchPad(uint8_t*, const uint8_t*);
    
93. 
    
94.   // read device's power requirements
    
95.   bool readPowerSupply(uint8_t*);
    
96. 
    
97.   // get global resolution
    
98.   uint8_t getResolution();
    
99.   
    
100.   // set global resolution to 9, 10, 11, or 12 bits
     
101.   void setResolution(uint8_t);
     
102. 
     
103.   // returns the device resolution, 9-12
     
104.   uint8_t getResolution(uint8_t*);
     
105. 
     
106.   // set resolution of a device to 9, 10, 11, or 12 bits
     
107.   bool setResolution(uint8_t*, uint8_t);
     
108.   
     
109.   // sets/gets the waitForConversion flag
     
110.   void setWaitForConversion(bool);
     
111.   bool getWaitForConversion(void);
     
112.   
     
113.   // sets/gets the checkForConversion flag
     
114.   void setCheckForConversion(bool);
     
115.   bool getCheckForConversion(void);
     
116.   
     
117.   // sends command for all devices on the bus to perform a temperature conversion
     
118.   void requestTemperatures(void);
     
119.    
     
120.   // sends command for one device to perform a temperature conversion by address
     
121.   bool requestTemperaturesByAddress(uint8_t*);
     
122. 
     
123.   // sends command for one device to perform a temperature conversion by index
     
124.   bool requestTemperaturesByIndex(uint8_t);
     
125. 
     
126.   // returns temperature in degrees C
     
127.   float getTempC(uint8_t*);
     
128. 
     
129.   // returns temperature in degrees F
     
130.   float getTempF(uint8_t*);
     
131. 
     
132.   // Get temperature for device index (slow)
     
133.   float getTempCByIndex(uint8_t);
     
134.   
     
135.   // Get temperature for device index (slow)
     
136.   float getTempFByIndex(uint8_t);
     
137.   
     
138.   // returns true if the bus requires parasite power
     
139.   bool isParasitePowerMode(void);
     
140.   
     
141.   bool isConversionAvailable(uint8_t*);
     
142. 
     
143.   #if REQUIRESALARMS
     
144.   
     
145.   typedef void AlarmHandler(uint8_t*);
     
146. 
     
147.   // sets the high alarm temperature for a device
     
148.   // accepts a char.  valid range is -55C - 125C
     
149.   void setHighAlarmTemp(uint8_t*, const char);
     
150. 
     
151.   // sets the low alarm temperature for a device
     
152.   // accepts a char.  valid range is -55C - 125C
     
153.   void setLowAlarmTemp(uint8_t*, const char);
     
154. 
     
155.   // returns a signed char with the current high alarm temperature for a device
     
156.   // in the range -55C - 125C
     
157.   char getHighAlarmTemp(uint8_t*);
     
158. 
     
159.   // returns a signed char with the current low alarm temperature for a device
     
160.   // in the range -55C - 125C
     
161.   char getLowAlarmTemp(uint8_t*);
     
162.   
     
163.   // resets internal variables used for the alarm search
     
164.   void resetAlarmSearch(void);
     
165. 
     
166.   // search the wire for devices with active alarms
     
167.   bool alarmSearch(uint8_t*);
     
168. 
     
169.   // returns true if ia specific device has an alarm
     
170.   bool hasAlarm(uint8_t*);
     
171. 
     
172.   // returns true if any device is reporting an alarm on the bus
     
173.   bool hasAlarm(void);
     
174. 
     
175.   // runs the alarm handler for all devices returned by alarmSearch()
     
176.   void processAlarms(void);
     
177.   
     
178.   // sets the alarm handler
     
179.   void setAlarmHandler(AlarmHandler *);
     
180.   
     
181.   // The default alarm handler
     
182.   static void defaultAlarmHandler(uint8_t*);
     
183. 
     
184.   #endif
     
185. 
     
186.   // convert from celcius to farenheit
     
187.   static float toFahrenheit(const float);
     
188. 
     
189.   // convert from farenheit to celsius
     
190.   static float toCelsius(const float);
     
191. 
     
192.   #if REQUIRESNEW
     
193. 
     
194.   // initalize memory area
     
195.   void* operator new (unsigned int);
     
196. 
     
197.   // delete memory reference
     
198.   void operator delete(void*);
     
199.   
     
200.   #endif
     
201. 
     
202.   private:
     
203.   typedef uint8_t ScratchPad[9];
     
204.   
     
205.   // parasite power on or off
     
206.   bool parasite;
     
207. 
     
208.   // used to determine the delay amount needed to allow for the
     
209.   // temperature conversion to take place
     
210.   uint8_t bitResolution;
     
211.   
     
212.   // used to requestTemperature with or without delay
     
213.   bool waitForConversion;
     
214.   
     
215.   // used to requestTemperature to dynamically check if a conversion is complete
     
216.   bool checkForConversion;
     
217.   
     
218.   // count of devices on the bus
     
219.   uint8_t devices;
     
220.   
     
221.   // Take a pointer to one wire instance
     
222.   OneWire* _wire;
     
223. 
     
224.   // reads scratchpad and returns the temperature in degrees C
     
225.   float calculateTemperature(uint8_t*, uint8_t*);
     
226.   
     
227.   void        blockTillConversionComplete(uint8_t*,uint8_t*);
     
228.   
     
229.   #if REQUIRESALARMS
     
230. 
     
231.   // required for alarmSearch
     
232.   uint8_t alarmSearchAddress[8];
     
233.   char alarmSearchJunction;
     
234.   uint8_t alarmSearchExhausted;
     
235. 
     
236.   // the alarm handler function pointer
     
237.   AlarmHandler *_AlarmHandler;
     
238. 
     
239.   #endif
     
240.   
     
241. };
     
242. #endif
     

复制代码

通过注释，发现几个关键：
1、#define TEMP_9_BIT  0x1F //  9 bit  是把什么地方改成0x1F 呢？
2、
  // get global resolution
  //得到全局分辨率
  uint8_t getResolution();
//目测这里是吧得到的分辨率值赋值给 uint8_t

  // set global resolution to 9, 10, 11, or 12 bits
  //设置全局分辨率为9，10，11，或12位
  void setResolution(uint8_t);
//如果将将这个uint8_t换成0x1F编译将直接报错

3、
  // returns the device resolution, 9-12
  //返回设备的分辨率，9-12
  uint8_t getResolution(uint8_t*);

  // set resolution of a device to 9, 10, 11, or 12 bits
  //一个装置的分辨率9，10，11，或12位
  bool setResolution(uint8_t*, uint8_t);
//如果将这个uint8_t换成0x1F编译将直接报错

hi55234

网上一个修改分辨率的程序，顿时凌乱了，菜鸟表示看不懂啊~~~

Code:

1. // set resolution of all devices to 9, 10, 11, or 12 bits
   
2. // if new resolution is out of range, it is constrained.
   
3. void DallasTemperature::setResolution(uint8_t newResolution)
   
4. {
   
5.   bitResolution = constrain(newResolution, 9, 12);
   
6.   DeviceAddress deviceAddress;
   
7.   for (int i=0; i<devices; i++)
   
8.   {
   
9.     getAddress(deviceAddress, i);
   
10. setResolution(deviceAddress, bitResolution);
    
11.   }
    
12. }
    
13. 
    
14. // set resolution of a device to 9, 10, 11, or 12 bits
    
15. // if new resolution is out of range, 9 bits is used.
    
16. bool DallasTemperature::setResolution(uint8_t* deviceAddress, uint8_t newResolution)
    
17. {
    
18.   ScratchPad scratchPad;
    
19.   if (isConnected(deviceAddress, scratchPad))
    
20.   {
    
21.     // DS18S20 has a fixed 9-bit resolution
    
22.     if (deviceAddress[0] != DS18S20MODEL)
    
23.     {
    
24.       switch (newResolution)
    
25.       {
    
26.         case 12:
    
27.           scratchPad[CONFIGURATION] = TEMP_12_BIT;
    
28.           break;
    
29.         case 11:
    
30.           scratchPad[CONFIGURATION] = TEMP_11_BIT;
    
31.           break;
    
32.         case 10:
    
33.           scratchPad[CONFIGURATION] = TEMP_10_BIT;
    
34.           break;
    
35.         case 9:
    
36.         default:
    
37.           scratchPad[CONFIGURATION] = TEMP_9_BIT;
    
38.           break;
    
39.       }
    
40.       writeScratchPad(deviceAddress, scratchPad);
    
41.     }
    
42. return true;  // new value set
    
43.   }
    
44.   return false;
    
45. }
    

复制代码