dsPIC30F2010 ds18B20 HD44780 LCD in MikroC

Introduction

The ds18S20/ds18B20 is one-wire precision digital temperature sensor. It implements only one data cable for command and data. The resolution of the ds18S20 is 9-bit while the ds18B20 is 12-bit higher resolution with floating point numbers.

A DS18B20 Sample from Ali Express

 

To interface with this sensor the master MCU program commonly uses the high speed Assembly language due to its fast response and its one-by-one instruction executions. However the manufactures of this chip (DALLAS) provide some sample programs written in C for the 8051-base devices.

Today using the Arduino is very common and ease of use for most of electronic hobbyists and engineers. There a lot of libraries and demo programs using this sensors. 

dsPIC30F2010 and ds18B20 Programming in MikroC

MikroC supports this one-wire digital temperature sensor for both the ds18S20 and the ds18B20. Unlike the Arduino libraries, using the MikroC One-Wire library, the master MCU need to process many steps such as writing command, reset, reading from scratch-pad, etc.

 

Schematic Diagram

In this example, the dsPIC30F2010 read the temperature data from a connected ds18B20 and it will be displayed on a character LCD. Both LCD and the sensor can be connect to any pins of an MCU upon the programming settings.

Edit Project

 

Timing is important for this one-wire sensor incorrect timing could cause command and data reading errors. The clock source is directly driven from an external 20MHz crystal oscillator without using Phase Lock Loop (PLL).

MikroC Source Code:

 

1. // LCD module connections
2. sbit LCD_RS at LATE0_bit;
3. sbit LCD_EN at LATE1_bit;
4. sbit LCD_D4 at LATE2_bit;
5. sbit LCD_D5 at LATE3_bit;
6. sbit LCD_D6 at LATE4_bit;
7. sbit LCD_D7 at LATE5_bit;
8. 
   
9. sbit LCD_RS_Direction at TRISE0_bit;
10. sbit LCD_EN_Direction at TRISE1_bit;
11. sbit LCD_D4_Direction at TRISE2_bit;
12. sbit LCD_D5_Direction at TRISE3_bit;
13. sbit LCD_D6_Direction at TRISE4_bit;
14. sbit LCD_D7_Direction at TRISE5_bit;
15. // End LCD module connections
16. 
    
17. // Set TEMP_RESOLUTION to the corresponding resolution of used DS18x20 sensor:
18. // 18S20: 9 (default setting; can be 9,10,11,or 12)
19. // 18B20: 12
20. const unsigned short TEMP_RESOLUTION = 12;
21. 
    
22. char *text = "000.0000";
23. unsigned temp;
24. 
    
25. void Display_Temperature(unsigned int temp2write) {
26. const unsigned short RES_SHIFT = TEMP_RESOLUTION - 8;
27. char temp_whole;
28. unsigned int temp_fraction;
29. 
    
30. // check if temperature is negative
31. if (temp2write & 0x8000) {
32. text[0] = '-';
33. temp2write = ~temp2write + 1;
34. }
35. 
    
36. // extract temp_whole
37. temp_whole = temp2write >> RES_SHIFT ;
38. 
    
39. // convert temp_whole to characters
40. if (temp_whole/100)
41. text[0] = temp_whole/100 + 48;
42. else
43. text[0] = '0';
44. 
    
45. text[1] = (temp_whole/10)%10 + 48; // Extract tens digit
46. text[2] = temp_whole%10 + 48; // Extract ones digit
47. 
    
48. // extract temp_fraction and convert it to unsigned int
49. temp_fraction = temp2write << (4-RES_SHIFT);
50. temp_fraction &= 0x000F;
51. temp_fraction *= 625;
52. 
    
53. // convert temp_fraction to characters
54. text[4] = temp_fraction/1000 + 48; // Extract thousands digit
55. text[5] = (temp_fraction/100)%10 + 48; // Extract hundreds digit
56. text[6] = (temp_fraction/10)%10 + 48; // Extract tens digit
57. text[7] = temp_fraction%10 + 48; // Extract ones digit
58. 
    
59. // print temperature on LCD
60. Lcd_Out(2, 5, text);
61. }
62. 
    
63. void main() {
64. 
    
65. ADPCFG = 0xFFFF; // Configure AN pins as digital
66. 
    
67. Lcd_Init(); // Initialize LCD
68. Lcd_Cmd(_LCD_CLEAR); // Clear LCD
69. Lcd_Cmd(_LCD_CURSOR_OFF); // Turn cursor off
70. Lcd_Out(1, 1, " Temperature: ");
71. // Print degree character, 'C' for Centigrades
72. Lcd_Chr(2,13,223); // different LCD displays have different char code for degree
73. // if you see greek alpha letter try typing 178 instead of 223
74. 
    
75. Lcd_Chr(2,14,'C');
76. 
    
77. //--- main loop
78. do {
79. //--- perform temperature reading
80. Ow_Reset(&PORTC, 14); // Onewire reset signal
81. Ow_Write(&PORTC, 14, 0xCC); // Issue command SKIP_ROM
82. Ow_Write(&PORTC, 14, 0x44); // Issue command CONVERT_T
83. Delay_us(120);
84. 
    
85. Ow_Reset(&PORTC, 14);
86. Ow_Write(&PORTC, 14, 0xCC); // Issue command SKIP_ROM
87. Ow_Write(&PORTC, 14, 0xBE); // Issue command READ_SCRATCHPAD
88. Delay_ms(400);
89. 
    
90. temp = Ow_Read(&PORTC, 14);
91. temp = (Ow_Read(&PORTC, 14) << 8) + temp;
92. 
    
93. //--- Format and display result on Lcd
94. Display_Temperature(temp);
95. 
    
96. Delay_ms(500);
97. } while (1);
98. }

 

LCD and One-Wire libraries are not include in project by default. So we need select these two drivers.

 

Go to View -> Library Manager

 

If we temperature reading program please check connection or set its correct resolutions - 9-bit for ds18S20 and 12-bit for ds18B20.

 

Program Testing on my DIY dsPIC30F2010 Prototype Board