OK6410 development board bare metal DS18B20 driver

I believe that those who have played with 51 should have played with DS18B20. Although it is used on ARM11, the operation is still the same. One more thing is that you need to switch the IO direction before reading and writing IO. In fact, 51 needs to be switched to a high level before reading, which is generally done by the compiler.

1. /****************************************************** *************************************************** ********** 

2.  * File name: ds18b20.c 

3.  * Function: S3C6410 DS18B20 driver 

4.  * Author: cp1300@139.com 

5.  * Created: September 17, 2012 22:45 

6.  * Last modified: September 17, 2012 

7.  * Details: Delay function support is required 

8.  * Make sure the delay accuracy is as high as possible 

9.  * Do not interrupt the reading process for a long time, because 1wire has strict timing requirements. 

10. *************************************************** *************************************************** *********/  

11. #include "system.h"  

12. #include "timer.h"  

13. #include "delay.h"  

14. #include "ds18b20.h"  

15.   

16.   

17. //DS18B20 uses GPIOE0  

18. #define Set18b20IOout() (rGPECON |= 1) //Set DS18B20 IO to output,  

19. #define Set18b20IOin() (rGPECON &= (~0xf)) //Set DS18B20 IO to floating input,  

20. #define Read18b20IO() ((rGPEDAT & BIT0) ? 1 : 0) //Read DS18B20 IO  

21. #define Write18b20IO(x) (x ? (rGPEDAT |= BIT0) : (rGPEDAT &= ~BIT0)) //Write DS18B20 IO  

22.   

23. /****************************************************** *************************************************** ************************ 

24. *Function: u8 DS18B20_Reset(void) 

25. *Function: Reset DS18B20 

26. *Parameters: None 

27. *Return: 0: success; 1: failure 

28. *Depends on: underlying macro definitions 

29. *Author : cp1300@139.com 

30. *Time: 20120917 

31. *Last modified: 20120917 

32. * Description: None 

33. *************************************************** *************************************************** *********************/  

34. u8 DS18B20_Reset(void)  

35. {  

36.     u8 i = 0;  

37.       

38.     Set18b20IOout(); //Host port push-pull output mode  

39.     Write18b20IO(1);  

40.     Delay_US(1);  

41.     Write18b20IO(0); //Pull the bus low for 480us~240us  

42.     Delay_US(500); //>480US delay  

43.     Write18b20IO(1);  

44.     Delay_US(2); //Reset completed  

45.     Set18b20IOin(); //Host port floating input mode  

46.     while(Read18b20IO()) //Wait for low level response signal  

47.     {  

48.         i++;  

49.         Delay_US(1);  

50.         if(i > 100)  

51.             return 1; //Waiting timeout, initialization failed, return 1;  

52.     }  

53.     Delay_US(250); //Skip reply signal  

54.     return 0x00; //DS18B20 detected and initialized successfully  

55. }  

56.   

57.   

58. /****************************************************** *************************************************** ************************ 

59. *Function: u8 DS18B20_ReadData(void) 

60. *Function: Read DS18B20 data 

61. *Parameters: None 

62. *Return: data 

63. *Depends on: underlying macro definitions 

64. *Author : cp1300@139.com 

65. *Time: 20120917 

66. *Last modified: 20120917 

67. * Description: None 

68. *************************************************** *************************************************** *********************/  

69. u8 DS18B20_ReadData(void)  

70. {  

71.     u8 i,data = 0;  

72.       

73.     for(i = 0;i < 8;i ++)  

74.     {  

75.         Set18b20IOout(); //Host port push-pull output mode  

76.         Write18b20IO(0); //Pull the bus low for 10-15us  

77.         data >>= 1;  

78.         Delay_US(12);  

79.         Write18b20IO(1); //Release the bus  

80.         Set18b20IOin(); //Host port floating input mode  

81.         Delay_US(1);  

82.         if(Read18b20IO()) //Read data, about 40-45us delay after reading  

83.             data |= 0x80;  

84.         Delay_US(42);  

85.     }  

86.     return data;  

87. }  

88.   

89.   

90. /****************************************************** *************************************************** ************************ 

91. *Function: void DS18B20_WriteData(u8 data) 

92. *Function: Write data to DS18B20 

93. *Parameter: data 

94. *Return: None 

95. *Depends on: underlying macro definitions 

96. *Author : cp1300@139.com 

97. *Time: 20120917 

98. *Last modified: 20120917 

99. * Description: None 

100. *************************************************** *************************************************** *********************/  

101. void DS18B20_WriteData(u8 data)  

102. {  

103.     u8 i;  

104.       

105.     Set18b20IOout(); //Host port push-pull output mode  

106.     for(i = 0;i < 8;i ++)  

107.     {  

108.         Write18b20IO(0); //Pull the bus low for 10-15us  

109.         Delay_US(12);  

110.         Write18b20IO(data & 0x01); //Write data bit, keep 20-45us  

111.         Delay_US(30);  

112.         Write18b20IO(1); //Release the bus  

113.         data >>= 1;  

114.         Delay_US(2);  

115.     }  

116. }  

117.   

118.   

119.   

120. /****************************************************** *************************************************** ************************ 

121. *Function: s16 DS18B20_ReadTemper(void) 

122. *Function: Read DS18B20 temperature 

123. *Parameters: None 

124. *Return: Temperature value 

125. *Depends on: underlying macro definitions 

126. *Author : cp1300@139.com 

127. *Time: 20120917 

128. *Last modified: 20120917 

129. * Note: The temperature value is expanded 100 times, and the temperature value is a signed number. 

130. *************************************************** *************************************************** *********************/  

131. s16 DS18B20_ReadTemper(void)  

132. {  

133.     u8th, tl;  

134.     s16 data;  

135.       

136.     if(DS18B20_Reset())   

137.     {  

138.         return 0xffff; //return error  

139.     }  

140.     DS18B20_WriteData(0xcc); //Skip reading serial number  

141.     DS18B20_WriteData(0x44); //Start temperature conversion  

142.     DS18B20_Reset();  

143.     DS18B20_WriteData(0xcc); //Skip reading serial number  

144.     DS18B20_WriteData(0xbe); //Read temperature  

145.     tl = DS18B20_ReadData(); //Read the lower eight bits  

146.     th = DS18B20_ReadData(); //Read the upper eight bits  

147.     data = th;  

148.     data <<= 8;  

149.     data |= tl;  

150.     data *= 6.25; //Expand the temperature value 100 times, accurate to 2 decimal places  

151.       

152.     return data;  

153. }  

1. #ifndef DS18B20_H_  

2. #define DS18B20_H_  

3.   

4.   

5. s16 DS18B20_ReadTemper(void); //Read DS18B20 temperature  

6.   

7. #endif /*DS18B20_H_*/  

DELAY.C

1. /****************************************************** *************************************************** ********** 

2.  * File name: delay.c 

3.  * Function: Delay function, call timer 1 for delay 

4.  * Author: cp1300@139.com 

5.  * Created: September 17, 2012 22:32 

6.  * Last modified: September 17, 2012 

7.  * Details: Delay error 1-2us, using timer 1 

8.  * Cannot be used in interrupt service routines 

9. *************************************************** *************************************************** *********/  

10. #include "system.h"  

11. #include "timer.h"  

12. #include "delay.h"  

13.   

14.   

15. /****************************************************** *************************************************** ************************ 

16. *Function: void Delay_US(u32 Delay) 

17. *Function: US delay 

18. *Parameter: Delay: delay time, unit US 

19. *Return: None 

20. *Depends on: underlying macro definitions 

21. *Author : cp1300@139.com 

22. *Time: 20120917 

23. *Last modified: 20120917 

24. * Note: If timer 0 is called for delay, then timer 0 cannot be used, and the delay error is 1US 

25. *************************************************** *************************************************** *********************/  

26. void Delay_US(u32 Delay)  

27. {  

28.     rTCFG0 |= 65; //Timer 0 pre-divided by 65+1, PCLK=66 provides clock, 66 division generates 1MHz timer clock  

29.     rTCON &= (~0xff); //Clear settings  

30.     rTCON |= BIT3; //Timer 0 automatic update enable  

31.     rTCNTB0 = Delay; //Reload value  

32.     rTINT_CSTAT |= BIT5; //Clear interrupt flag  

33.     rTINT_CSTAT &= ~BIT0; //Disable timer 0 interrupt  

34.     //The following operation starts timer 0  

35.     rTCON |= BIT1; //manual update  

36.     rTCON &= ~BIT1; //End manual update  

37.     rTCON |= BIT0; //Start timer 0      

38.     while(!(rTINT_CSTAT & BIT5)); //Wait for the delay to arrive  

39.     rTINT_CSTAT |= BIT5; //Clear interrupt flag  

40. }  

41.   

42.   

43.   

44. /****************************************************** *************************************************** ************************ 

45. *Function: void Delay_MS(u32 Delay) 

46. *Function: MS delay 

47. *Parameter: Delay: delay time, unit US 

48. *Return: None 

49. *Depends on: underlying macro definitions 

50. *Author : cp1300@139.com 

51. *Time : 20120918 

52. *Last modified: 20120918 

53. * Note: If timer 0 is called for delay, then timer 0 cannot be used, and the delay error is <1ms 

54. *************************************************** *************************************************** *********************/  

55. void Delay_MS(u32 Delay)  

56. {  

57.     while(Delay --)  

58.     {  

59.         Delay_US(1000);  

60.     }  

61. }  

Later, this program will be ported to LINUX as a DS18B20 driver.