This article shows how to get started with PIC18F4550 microcontroller USART module using CCS PIC C compiler.
PIC18F4550 microcontroller has one (1) USART (Universal Synchronous/Asynchronous Receive/Transmit) module. This module can work in USRT mode or UART mode. In this topic we are going to use the USART module as UART (Universal Asynchronous Receive/Transmit) to transmit and receive data between the microcontroller and the computer.
PIC18F4550 UART connection circuit schematic:
Pin RC6 (TX) and pin RC7 (RX) are used for the UART (serial) communication between the microcontroller and the computer. To change between TTL logic levels (5V) and RS232 signals (+/-12V), an IC is needed which is max232.
Don't connect TX and RX pins directly to an RS232 serial port which may damage your microcontroller.
This is the full C code of this example.
// CCS C UART example for PIC18F4550 microcontroller // http://ccspicc.blogspot.com/ // electronnote@gmail.com #include <18F4550.h> #fuses NOMCLR INTRC_IO #use delay(clock = 8000000) #use rs232(uart1, baud = 9600) // Initialize UART module #include <string.h> char message[] = "PIC18F4550 microcontroller UART example" ; char i, j, textsize; void main(){ setup_oscillator(OSC_8MHZ); // Set internal oscillator to 8MHz putc(13); // Go to first column printf("Hello world!"); // UART write delay_ms(5000); // Wait 5 seconds putc(13); // Go to first column putc(10); // Start a new line textsize = strlen(message); // Number of characters in message for(j = 0; j < textsize; j++){ putc(message[j]); delay_ms(100); } putc(13); // Go to first column putc(10); // Start a new line while(TRUE){ if(kbhit()){ // If data has been received i = getc(); // UART read putc(i); // Send it back } } }
PIC18F4550 UART example video:
The following video shows communication between the computer and PIC18F4550 using UART module.
