dsPIC30F2010 MikroC for dsPIC UART Example

Overview

The UART is a simple serial communication interface exists in most of micro-controllers. Its protocol is very simple. A build-in UART module of a micro-controller offer a high speed, configurable and reliable data communication. This module doesn't exist in some low-end 8-bit micro-controller for example the PIC16F54 or the popular PIC16F84A. However the programmer can emulate this communication protocol in firmware such Assembly or even embedded C programming language (Software UART) due to its clarity. Some C compilers have their software UART allowing the user access to their build-in function libraries.

 

UART Received ASCII Data

 

This communication interface is used to interact between micro-controller to microcontroller due to its two data wire - Transmit (TX) and Receive (RX). Some peripheral device such as GSM module, Wi-Fi modem (ESP8266), or HMI use UART.

 

MikroC for dsPIC UART Library

MikroC has built-in UART library that supports both hardware and software UART. Hardware UART implements the internal dedicated UART modules of any 16-bit PIC micro-controllers. Some 16-bit PIC micro-controllers have more than one UART interface, UART1, UART2, etc.

These are MikroC Hardware UART Library Routines:

Library Routines

• UARTx_Init
• UARTx_Init_Advanced
• UARTx_Data_Ready
• UARTx_Tx_Idle
• UARTx_Read
• UARTx_Read_Text
• UARTx_Write
• UARTx_Write_Text
• UART_Set_Active

Generic Routines

• UART_Data_Ready
• UART_Tx_Idle
• UART_Read
• UART_Read_Text
• UART_Write
• UART_Write_Text

 

Now let test the UART1 communication interface of the dsPIC30F2010 using the MikroC UART example.

MikroC Source Code:

1. 
   
2. char uart_rd;
3. 
   
4. void main() {
5. 
   
6. UART1_Init(9600); // Initialize UART module at 9600 bps
7. Delay_ms(100); // Wait for UART module to stabilize
8. 
   
9. // U1MODEbits.ALTIO = 1; // Un-comment this line to have Rx and Tx pins on their alternate
10. // locations. This is used to free the pins for other module, namely the SPI.
11. 
    
12. UART1_Write_Text("Start");
13. UART1_Write(10);
14. UART1_Write(13);
15. 
    
16. while (1) { // Endless loop
17. if (UART1_Data_Ready()) { // If data is received,
18. uart_rd = UART1_Read(); // read the received data,
19. UART1_Write(uart_rd); // and send data via UART
20. }
21. }
22. }

 

In the Library Manger Window, Tick on UART. Then build the source code.

 

UART in Library Manager

 

In MikroC IDE, go to Tools -> USART Terminal to open the interface.

 

USART Terminal

 

Enter any characters and click Send, then the MCU will send back the received data. UART requires a precise micro-controller timing. So don't forget to set a correct clock source and frequency.

Let put a character LCD that displays received ASCII characters from PC Serial Port Terminal.

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. char txt1[] = "dsPIC30F2010";
18. char txt2[] = "UART Example";
19. char txt3[] = "Lcd4bit";
20. char txt4[] = "example";
21. 
    
22. char i=1;
23. char uart_rd;
24. 
    
25. void main(){
26. ADPCFG = 0xFFFF; // Configure AN pins as digital I/O
27. 
    
28. Lcd_Init(); // Initialize LCD
29. UART1_Init(9600); // Initialize UART module at 9600 bps
30. Delay_ms(100); // Wait for UART module to stabilize
31. UART1_Write_Text("Reply for dsPIC30F2010 MCU");
32. UART1_Write(10);
33. UART1_Write(13);
35. Lcd_Cmd(_LCD_CLEAR); // Clear display
36. Lcd_Cmd(_LCD_CURSOR_OFF); // Cursor off
37. Lcd_Out(1,3,txt1); // Write text in first row
38. 
    
39. Lcd_Out(2,3,txt2); // Write text in second row
40. Delay_ms(5000);
41. 
    
42. Lcd_Cmd(_LCD_CLEAR); // Clear display
43. Delay_ms(10);
44. Lcd_Out(1, 1 ,"PC Terminal:");
45. 
    
46. while(1) { // Endless loop
47. if (UART1_Data_Ready()) { // If data is received,
48. uart_rd = UART1_Read(); // read the received data,
49. UART1_Write(uart_rd); // and send data via UART
50. Lcd_Chr(2, i, uart_rd);
51. i++;
52. }
53. if(i>15) {
54. i = 1;
55. Lcd_Cmd(_LCD_CLEAR);
56. Delay_ms(10);
57. Lcd_Out(1 ,1 ,"PC Terminal:");
58. }
59. }
60. }

 

The LCD shows UART characters, and the MCU will clears it automatically whenever the UART receiving counts reach 15.

Schematic:

Schematic Diagram in Proteus

dsPIC30F2010 Prototype Board Testing:

 

Serial Port Terminal

 

Testing Program

 

UART ASCII Data Receiving

Using the Sprint Library

The mikroC PRO for dsPIC30/33 and PIC24 provides the standard ANSI C Sprintf function for easy data formatting.

Note : In addition to ANSI C standard, the Sprint Library also includes two limited versions of the sprintf function (sprinti and sprintl)
         These functions take less ROM and RAM and may be more convenient for use in                 some cases.  

Functions

• sprintf
• sprintl
• sprinti

 

Since UART terminal accept only binary ASCII codes. Other data types such as array, integer or floating point numbers could not be directly transmitted over this communication protocol. So additional C function libraries is useful for converting non-ASCII characters into a readable ASCII characters.

 

MikroC Source Code:

 

1. double ww = -1.2587538e+1;
2. char buffer[15];
3. 
   
4. void main(){
5. 
   
6. UART1_Init(9600); // Initialize UART module at 4800 bps
7. Delay_ms(10);
8. 
   
9. UART1_Write_Text("Floating point number representation"); // Write message on UART
10. 
    
11. sprintf(buffer, "%12e", ww); // Format ww and store it to buffer
12. UART1_Write_Text("rne format:"); // Write message on UART
13. UART1_Write_Text(buffer); // Write buffer on UART
14. 
    
15. sprintf(buffer, "%12f", ww); // Format ww and store it to buffer
16. UART1_Write_Text("rnf format:"); // Write message on UART
17. UART1_Write_Text(buffer); // Write buffer on UART
18. 
    
19. sprintf(buffer, "%12g", ww); // Format ww and store it to buffer
20. UART1_Write_Text("rng format:"); // Write message on UART
21. UART1_Write_Text(buffer); // Write buffer on UART
22. }

 

We need to set a correct on board clock to 20MHz HS, and also include the UART and SPrint Library in Library Manager.

 

USART Terminal