Hey guys!

I've an assignment that requires me to connect 2 sensors on the same PORT A. So I was thinking of using bit0 and bit1 for the ADC conversion. I looked through all the sample codes and my school's textbook, however, can't find a way to configure 2 pins at the same time. Currently I am using Mplabv8.63 compiler.

So far, I have only managed to get my temperature sensor(Lm35) working and to display the output reading. However, I can't seem to integrate another sensor onto the same codes. This codes were taken from http://forum.allaboutcircuits.com/threads/lm35-temperature-sensor.59885/

1. //Temperature Sensor - Convert the Analog signal to Digital and Display it to the LCD Display Board
2. 
   
3. #include <p18F4550.h>
4. #include <delays.h>
5. #include "lcd.h"
6. // ************** ErnieM Addition Start ****************
7. #include <stdlib.h> // added to get itoa() function to convert t into a string
8. // ************** ErnieM Addition End ****************
9. 
   
10. 
    
11. 
    
12. // Include this when using Bootloader Program ================================
13. #pragma udata
14. 
    
15. extern void _startup (void); // See c018i.c in your C18 compiler dir
16. #pragma code _RESET_INTERRUPT_VECTOR = 0x000800
17. void _reset (void)
18. {
19. _asm goto _startup _endasm
20. }
21. #pragma code
22. 
    
23. #pragma code _HIGH_INTERRUPT_VECTOR = 0x000808
24. void _high_ISR (void)
25. {
26. ;
27. }
28. 
    
29. #pragma code _LOW_INTERRUPT_VECTOR = 0x000818
30. void _low_ISR (void)
31. {
32. ;
33. }
34. #pragma code
35. 
    
36. #pragma code
37. 
    
38. // additional codes ends here ===============================================================
39. 
    
40. // Your program declarations start here:====
41. 
    
42. 
    
43. #define LCD_RS PORTDbits.RD6 // Register Select on LCD
44. #define LCD_EN PORTDbits.RD4 // Enable on LCD controller
45. #define LCD_WR PORTDbits.RD5 // Write on LCD controller
46. 
    
47. 
    
48. //--- Function for writing a command byte to the LCD in 4 bit mode -------------
49. 
    
50. void lcd_write_cmd(signed char cmd)
51. {
52. unsigned char temp2;
53. LCD_RS = 0; // Select LCD for command mode
54. Delay10TCYx(4); // 40us delay for LCD to settle down
55. temp2 = cmd;
56. temp2 = temp2 >> 4; // Output upper 4 bits, by shifting out lower 4 bits
57. PORTD = temp2 & 0x0F; // Output to PORTD which is connected to LCD
58. 
    
59. Delay1KTCYx(10); // 10ms - Delay at least 1 ms before strobing
60. lcd_strobe();
62. Delay1KTCYx(10); // 10ms - Delay at least 1 ms after strobing
63. 
    
64. temp2 = cmd; // Re-initialise temp2
65. PORTD = temp2 & 0x0F; // Mask out upper 4 bits
66. 
    
67. Delay1KTCYx(10); // 10ms - Delay at least 1 ms before strobing
68. lcd_strobe();
69. Delay1KTCYx(10); // 10ms - Delay at least 1 ms before strobing
70. 
    
71. }
72. 
    
73. //---- Function to write a character data to the LCD ---------------------------
74. 
    
75. void lcd_write_data(char data)
76. {
77. char temp1;
78. 
    
79. LCD_RS = 1; // Select LCD for data mode
80. Delay10TCYx(4); // 40us delay for LCD to settle down
81. 
    
82. temp1 = data;
83. temp1 = temp1 >> 4;
84. PORTD = temp1 & 0x0F;
85. Delay1KTCYx(10);
86. LCD_RS = 1;
87. Delay1KTCYx(10); //_-_ strobe data in
88. 
    
89. lcd_strobe();
90. Delay1KTCYx(10);
91. 
    
92. temp1 = data;
93. PORTD = temp1 & 0x0F;
94. Delay1KTCYx(10);
95. LCD_RS = 1;
96. Delay1KTCYx(10); //_-_ strobe data in
97. 
    
98. lcd_strobe();
99. Delay1KTCYx(10);
100. }
101. 
     
102. //-- Function to generate the strobe signal for command and character----------
103. 
     
104. void lcd_strobe(void) // Generate the E pulse
105. {
106. LCD_EN = 1; // E = 0
107. Delay1KTCYx(100); // 10ms delay for LCD_EN to settle
108. LCD_EN = 0; // E = 1
109. Delay1KTCYx(100); // 10ms delay for LCD_EN to settle
110. }
111. 
     
112. 
     
113. //---- Function to initialise LCD module ----------------------------------------
114. void lcd_init(void)
115. {
116. TRISD = 0x00;
117. PORTD = 0x00; // PORTD is connected to LCD data pin
118. LCD_EN = 0;
119. LCD_RS = 0; // Select LCD for command mode
120. LCD_WR = 0; // Select LCD for write mode
121. 
     
122. Delay10KTCYx(250); // Delay a total of 1 s for LCD module to
123. Delay10KTCYx(250); //
124. Delay10KTCYx(250); //
125. Delay10KTCYx(250); // finish its own internal initialisation
126. 
     
127. /* The data sheets warn that the LCD module may fail to initialise properly when
128. power is first applied. This is particularly likely if the Vdd
129. supply does not rise to its correct operating voltage quickly enough.
130. 
     
131. It is recommended that after power is applied, a command sequence of
132. 3 bytes of 30h be sent to the module. This will ensure that the module is in
133. 8-bit mode and is properly initialised. Following this, the LCD module can be
134. switched to 4-bit mode.
135. */
136. 
     
137. lcd_write_cmd(0x33);
138. lcd_write_cmd(0x32);
140. lcd_write_cmd(0x28); // 001010xx – Function Set instruction
141. // DL=0 :4-bit interface,N=1 :2 lines,F=0 :5x7 dots
142. 
     
143. lcd_write_cmd(0x0E); // 00001110 – Display On/Off Control instruction
144. // D=1 isplay on,C=1 :Cursor on,B=0 :Cursor Blink on
145. 
     
146. lcd_write_cmd(0x06); // 00000110 – Entry Mode Set instruction
147. // I/D=1 :Increment Cursor position
148. // S=0 : No display shift
149. 
     
150. lcd_write_cmd(0x01); // 00000001 Clear Display instruction
151. 
     
152. Delay1KTCYx(20); // 20 ms delay
153. 
     
154. }
155. 
     
156. void main(void)
157. {
158. // ************** ErnieM Addition Start ****************
159. // add these variables
160. char Buffer[10]; // buffer to hold your temperature character string
161. unsigned int i; // index variable
162. // moved your "t" variable up here, C18 wants to see variables defined at the
163. // very start of a block. Other compilers let you make a definition anywhere,
164. // this C28 compiler seems to want them up top like this
165. unsigned int t; // variable for temperature
166. // ************** ErnieM Addition End ****************
167. 
     
168. // Do not remove these as well=============
169. ADCON1 = 0x0F; // Configure PORTA to be digital I/O
170. CMCON = 0x07;
171. // ========================================
172. // Your MAIN program Starts here: =========
174. lcd_init(); // Initialise LCD module
175. 
     
176. LCD_RS = 1; // Select LCD for character data mode
177. Delay1KTCYx(1); // 1 ms delay
178. 
     
179. /* Initialise analog to digital conversion setting */
180. 
     
181. ADCON0 = 0b00000001; // bit5-2 0000 select channel 0 conversion
182. // bit1 A/D conversion status bit
183. // 1- GO to starts the conversion
184. // 0 - DONE when A/D is completed
185. // bit0 Set to 1 to power up A/D
186. 
     
187. ADCON1 = 0b00001100; // bit5 reference is VSS
188. // bit4 reference is VDD
189. // bit3-0 AN2 to AN0 Analog, the rest Digital
190. 
     
191. ADCON2 = 0b10010110; // bit7 : A/D Result Format. 0 Left, 1 Right justified ( Set it to 1, Right Justified)
192. // bit5-3 : 010 acquisition time = 4 TAD
193. // bit2-0 : 110 conversion clock = Tosc / 16
194. // ************** ErnieM Addition Start ****************
195. // I'm going to change your loops so it measures the temperature every second
196. // then displays it.
197. // for(;
198. // {
199. // ************** ErnieM Addition End ****************
200. 
     
202. // ************** ErnieM Addition Start ****************
203. // this code moved down below into the once a second loop
204. // ADCON0bits.GO = 1; // This is bit2 of ADCON0, START CONVERSION NOW
206. // while(ADCON0bits.GO == 1); // Waiting for DONE
207. 
     
208. // t = (ADRES * 500) / 255; //Convert to Degree Celcius - ADRES (16bit) is the output of ADC
209. // ************** ErnieM Addition End ****************
211. // ************** ErnieM Addition Start ****************
212. // removed this loop
213. // while(1)
214. // {
215. // ************** ErnieM Addition End ****************
216. lcd_write_cmd(0x80); // Move cursor to line 1 position 1
217. 
     
218. lcd_write_data('T');
219. lcd_write_data('E');
220. lcd_write_data('M');
221. lcd_write_data('P');
222. lcd_write_data('E');
223. lcd_write_data('R');
224. lcd_write_data('A');
225. lcd_write_data('T');
226. lcd_write_data('U');
227. lcd_write_data('R');
228. lcd_write_data('E');
229. lcd_write_data(':');
231. // ************** ErnieM Addition Start ****************
232. // HERE is where we'll loop
233. while(1)
234. {
235. // measure temperature
236. ADCON0bits.GO = 1; // This is bit2 of ADCON0, START CONVERSION NOW
237. while(ADCON0bits.GO == 1); // Waiting for DONE
238. t = (ADRES * 500) / 255; //Convert to Degree Celcius - ADRES (16bit) is the output of ADC
240. lcd_write_cmd(0xC0); // Move cursor to line 2 position 1
241. 
     
242. // lcd_write_data(t); // Display the temperature
243. 
     
244. // we can't just drint the integer, need to first convert the number into a character string
245. // convert t to a string
246. itoa(t,Buffer);
247. // print that string!
248. i = 0;
249. while (Buffer != 0) lcd_write_data(Buffer[i++]);
     [*]
     
     [*]
     
     [*] lcd_write_data(0xDF);
     [*] lcd_write_data('C');
     [*]
     
     [*] Delay10KTCYx(250); // Delay a total of 1 s
     [*] Delay10KTCYx(250); //
     [*] Delay10KTCYx(250); //
     [*] Delay10KTCYx(250); // so the screen doesn't "flash" too much on updates
     [*]// for the future: Save the old value of t, and only update the screen
     [*]// when a new temperature is measured. That way you don't need that 1 sec delay
     [*]
     [*]
     
     [*] }
     [*]// ************** ErnieM Addition End ****************
     [*]
     
     [*]
     [*]
     
     [*]
     [*]// ************** ErnieM Addition Start ****************
     [*]// removed infinite "stop here" loop
     [*]// while(1); //stop here for now
     [*]
     
     [*]
     
     [*]// }
     [*]// }
     [*]
     
     [*]// ************** ErnieM Addition End ****************
     [*]} // end of main()
     

Can somebody please advise me on how to configure another pin so I can add another sensor on the same port.(If it's even possible)

Thankyou!

 

You select the channel in ADCON0,

Your programme line 181...

 

Is it necessary to post the whole code?

Coul you edit and suppres what is not relevant?

Use the "code" tags

 

Sorry im new to this

 

Sorry im new to this

OK. Go an edit the OP then.

 

Hey!

You select the channel in ADCON0,

Thanks for the response. I wanna make use of pin0 and pin1. So far I've got this:

int value1, value2; //to store value 1 and 2
ADCON1 = 0x0D; // to select AN0(RA0) and AN1(RA1) as analog input
ADCON2 = 0x__; // i dunno the value but set as FOSC/4 and right justified
ADCON0 = 0x01; //select AN0
ADCON0bits.GO = 1; //start conversion
while(ADCON0bits.GO == 1); //wait for conversion to finish
value1 = (ADRESH*256)+ADRESL;
ADCON0 = 0x05; //select AN1(RA1)
ADCON0bits.GO = 1; //start conversion
while(ADCON0bits.GO == 1); //wait for conversion to finish
value2 = (ADRESH*256)+ADRESL;

This way value 1 and 2 contain the ADC values for AN0 and AN1 respectively.