} Program to transmit a string to PC using UART After that, the data is taken from the RCREG register.Īfter complete reception, RCIF should also be made to 0. To ensure the data is completely received, we will wait till RCIF bit is set. After this, we will wait till the TXIF bit is set to ensure the transaction is complete.īefore leaving the function, TXIF is made 0 again. To transmit the character, first, the character should be loaded into the TXREG register. Inside the while loop, The character returned from receive function is stored to variable ‘a’ and then it is transmitted back to the computer to display using the transmit function.value for SPBRG is calculated for Baudrate of 9600 using the formula.To enable the Serial ports and Continues receiving RCSTA will take the value 0x90.To Enable transmission and to work in Asynchronous 8 bit mode TXSTA is given the value 0x24.The Tx pin must be set as output and Rx will be input.In the main function, we will do all the required configuration for the UART module. You can get detailed instructions on setting up configuration bits here. I have also included the file containing the configuration bits ‘Config.h’. Program to receive and transmit a character using UARTįirst, the xc.h header should be used to access compiler and device-specific features. Given the desired baud rate and FOSC, the nearest integer value for the SPBRG register can be calculated using the below formula. SPBRG is an 8-bit register that controls the baud rate generation. Both the devices Rx/Tx should be set to the same baud rate for successful communication. The main criterion for UART communication is its baud rate. RX9D: 9th bit of Received Data (can be parity bit but must be calculated by user firmware).1 = Overrun error (can be cleared by clearing bit CREN).1 = Framing error (can be updated by reading RCREG register and receive next valid byte).0 = Disables address detection, all bytes are received and the ninth bit can be used as a parity bit.1 = Enables address detection, enables interrupt and load of the receive buffer when RSR is set.1 = Serial port enabled (configures RC7/RX/DT and RC6/TX/CK pins as serial port pins).TX9D: 9th bit of Transmit Data, can be Parity bit.TRMT: Transmit Shift Register Status bit.So now, let’s see how these registers can be configured. Here, TXSTA and RCSTA are the control registers. Register configurationīefore moving on to program lets understand the registers associated with PIC16F877A UART. So the same value should be set in RealTerm. We will be configuring our UART to work on a Baud rate of 9600. Make sure you chose the right port and Baud rate in Realterm. we will use the serial terminal, ‘ RealTerm’ for transmitting and receiving data from the computer side. This tutorial will focus on receiving a character typed on PC and then transmitting that back to PC to display on the screen. TTL – RS232 converter circuit TTL – USB converter circuit But if you want to build your own, use the below circuits. TTL – RS232 or TTL USB converter modules can be easily purchased. Also, you may directly use a TTL to USB converter. If your PC doesn’t have a DB9 port, you might want to use an RS232 to USB converter. This can be achieved using a DB9 connector. which is a level translator that helps the PIC Microcontroller to connect with a PC using RS-232 telecommunications standard. In this tutorial, we learn to Enable the inbuilt hardware module for UART in PIC16F877A Microcontroller and how to communicate with your Computer using the UART protocol.įor this, we will use an IC called MAX232. Serial communication using a Microcontroller is one of the easiest operations to learn on a microcontroller and it comes into use in almost every application. A universal asynchronous receiver-transmitter is a hardware module for asynchronous serial communication in which the data format and transmission speeds are configurable.
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