Avr Software Uart In C

AVR/Arduino RFID Reader with UART Code in C Posted By: Admin on: June 23, 2012 In: AVR ATmega Projects, Interfacing(USB - RS232 - I2c -ISP) Projects, RFID - NFC Projects No Comments Print Email. 82 Added support for 48P, 88P, 168P, and 328P by adding them to the. AVR serial communication UART tutorial using Embedded C language code program built AVR studio software AVR microcontroller tutorials embedded design system.

Since ATtiny13 does not have hardware USART/UART in some cases we’re forced to use SoftwareUART. In this example project a simple bit-banging UART has been presented. Compiled for both TX and RX it uses just 248 bytes of flash. Default serial configuration is 8/N/1 format at 19200 baud (lowest error rates during tests). It can be easily changed to other standard RS-232 baudrate. Note that it is a great solution for a simple debug/logging but to other purposes I would recommend using an AVRs with a built-in UART. The code is on Github, click here.

Edit: To make a simpler integration with external projects I have created a little library:

Parts Required

  • ATtiny13 – i.e. MBAVR-1 development board

Circuit Diagram

Serial communications tools

1) TTL Serial Adapter (UART <-> USB converter)

2) Serial terminal

I usually use CuteCom – a graphical serial port communications program, similar to Minicom.

Or python scripts, i.e.:

Firmware

This code is written in C and can be compiled using the avr-gcc. More details on how compile this project is here.

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Avr Software Uart In C Code

The microcontroller PIC16F84A has no hardware UART module, but we can use software UART to send/receive data to/from the PC via RS232 cable (COM port). This topic shows a simple example for the use of the UART protocol with the PIC16F84A MCU.

Hardware Required:

Software

Avr Software Uart In C Pdf

  • PIC16F84A microcontroller
  • 8MHz crystal
  • 2 x 22pF ceramic capacitors
  • 10K ohm resistor
  • MAX232 — datasheet
  • 4 x 10uF polarized capacitor
  • Female RS232 connector
  • Breadboard
  • 5V power source
  • Jumper wires

Avr Software Uart In Color

UART Example for PIC16F84A microcontroller circuit:

Avr Software Uart In C Tutorial

To interface the PIC16F84A MCU with the PC we need MAX232 signal level converter as shown in the circuit diagram. There are 2 lines between the PIC16F84A and the MAX232 and also two lines between the MAX232 and the female COM connector. One line for data transmit and the other one for data receive.
The female COM connector is connected to the PC using RS232 cable, this cable has to be male-female because the PC RS232 port type is male.
In this example the PIC16F84A MCU runs with 8MHz crystal oscillator.

UART Example for PIC16F84A microcontroller C code:
The function #use rs232(xmit = PIN_B4, rcv = PIN_B5, baud = 2400) is used to configure the UART protocol. Here software UART is used.
where:
xmit is the transmit pin (RB4)
rcv is the receive pin (RB5)
2400 is the baud rate.
The functions used in the C code are:
printf: sends a string of characters over RS232 transmission pin (TX).
putc: send a character over RS232 transmission pin (TX).
getc(): read character if available.
Complete C code for CCS C compiler is below.

Avr Software Uart