dsPIC30F2010 ADC Programming in MikroC

Introduction

An Analog to Digital Converter (ADC) translates continuous voltage signal into a digital data that a digital or computer system could understands. For short, in most of modern micro-controllers have at least one dedicated ADC module inside. It range from 8-bit, 10-bit, 12-bit or even 16-bit in a mixed signal processor such as the MSP430 micro-controller series.

 

An ADC is needed in an audio sampling system, analog temperature reading, strain gauge, etc. Using a micro-controller's build-in ADC module is very cost effective reducing of complexities in hardware wiring. 

 

10-BIT HIGH SPEED A/D FUNCTIONAL BLOCK DIAGRAM

 

The dsPIC30F2010 has six-channel 10-bit ADC module that able to convert any analog input channel up to 500KSPS. It has a programmable reference voltage pins - AVREF+ and AVREF-, and select able ADC supply voltage pins - AVDD and AVSS . 

In some compilers there is no ADC library. So the programmer need configures its registers before allowing the ADC module to operate.

The A/D module has six 16-bit registers:

• A/D Control Register1 (ADCON1)
• A/D Control Register2 (ADCON2)
• A/D Control Register3 (ADCON3)
• A/D Input Select Register (ADCHS)
• A/D Port Configuration Register (ADPCFG)
• A/D Input Scan Selection Register (ADCSSL) 

 

The programmer needs to configure its, clock source/frequency, result preparation, number of analog inputs, reference voltage pins, etc.

 

dsPIC30F2010 ADC Programming in MikroC

Using MikroC, reading any ADC inputs is very easy. Because it has a ready-to-use function library. 

Library Routines

• ADCx_Init
• ADCx_Init_Advanced
• ADCx_Get_Sample
• ADCx_Read
• ADC_Set_Active
• ADC1_ActivateCore

ADC AN4 and LED 

Here I make a simple ADC reading example from AN4 pin that connects to a POT (on-board). I use its 10-bit resolution that ranges from 0 to 1023. If the result is over 512 an LED connects to RD0 will turn on, otherwise it will turns off.

 

Schematic Diagram: 

 

Schematic Diagram

 

It's the same to my dsPIC30F2010 DIY Prototype Board.

 

MikroC Source Code:

 

1. 
   unsigned int temp_res;
2. 
   
3. void main() {
4. 
   
5. TRISB = 0xFFFF; // PORTB is input
6. TRISD = 0; // PORTD is output
7. TRISF = 0; // PORTF is output
8. ADC1_Init(); // Enable ADC module
9. 
   
10. do {
11. temp_res = ADC1_Read(4); // Get 10-bit results of AD conversion
12. if(temp_res>=512) LATD=0;
13. else LATD=1;
14. } while(1);
15. }

 

ADC AN4 and Character LCD

Following the Mikroelektronika Development Board example, I use a character LCD to read the analog input from AN4, showing its analog voltage result on a 16x4 character LCD. 

 

Schematic Diagram

 

Schematic Diagram

 

 The voltage value displaying is in floating point format.

 

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. unsigned char ch;
18. unsigned int adc_rd;
19. char *text;
20. long tlong;
21. 
    
22. void main() {
23. ADPCFG = 0xFFFF; // Configure AN pins as digital
24. 
    
25. Lcd_Init();
26. LCD_Cmd(_LCD_CURSOR_OFF); // send command to LCD (cursor off)
27. LCD_Cmd(_LCD_CLEAR); // send command to LCD (clear LCD)
28. 
    
29. text = "mikroElektronika"; // assign text to string
30. LCD_Out(1,1,text); // print string a on LCD, 1st row, 1st column
31. text = "LCD example"; // assign text to string
32. LCD_Out(2,3,text); // print string a on LCD, 2nd row, 1st column
33. 
    
34. Delay_ms(7000);
35. text = "dsPIC30F2010 ADC";
36. LCD_Out(1,1,text);
37. text = "Voltage: "; // assign text to string
38. while (1) {
39. adc_rd = ADC1_read(4); // get ADC value from 2nd channel
40. LCD_Out(2,1,text); // print string a on LCD, 2nd row, 1st column
41. 
    
42. tlong = (long)adc_rd * 5000; // covert adc reading to milivolts
43. tlong = tlong / 1023; // 0..1023 -> 0-5000mV
44. 
    
45. ch = tlong / 1000; // extract volts digit
46. LCD_Chr(2,10,48+ch); // write ASCII digit at 2nd row, 9th column
47. LCD_Chr_CP('.');
48. 
    
49. ch = (tlong / 100) % 10; // extract 0.1 volts digit
50. LCD_Chr_CP(48+ch); // write ASCII digit at cursor point
51. 
    
52. ch = (tlong / 10) % 10; // extract 0.01 volts digit
53. LCD_Chr_CP(48+ch); // write ASCII digit at cursor point
54. 
    
55. LCD_Chr_CP('V');
56. 
    
57. Delay_ms(100);
58. }
59. }//~!

 

I tested this example on my DIY dsPIC30F2010 Prototype Board.

 

Reading +5.00V

  

Reading +2.53V

  

Reading 0.00V

Sending the ADC Data Over The Serial Port

We can send the ADC conversion data over the serial port using additional C sprintf and UART function.

 

MikroC Source Code:

1. 
   unsigned int adc_rd;
2. char *text;
3. float voltage;
4. 
   
5. void main() {
6. ADPCFG = 0xFFFF;
7. // Initialize UART module at 9600 bps
8. UART1_Init(9600);
9. Delay_ms(10);
10. text = "dsPIC30F2010 ADC UART Example\n\r";
11. UART1_Write_Text(text); // Write message on UART
12. 
    
13. while(1){
14. adc_rd = ADC1_read(4);
15. voltage = 5.0 * adc_rd / 1023;
16. sprintf(text,"AN4 Channel ADC Value: %d Decimal\n\r",adc_rd);
17. UART1_Write_Text(text); // Write message on UART
18. sprintf(text,"%0.2f Volts\n\r",voltage);
19. UART1_Write_Text(text); // Write message on UART
20. Delay_ms(2000);
21. }
22. }

 In the Library Manager, don't forget to tick on ADC, UART and Sprintf functions.

 

USART Terminal