Summary of AVR terminal for serial port using TSOP1738 microcontroller
This article describes an AVR-based terminal project featuring an HD44780 LCD, 8 multiplexed LEDs, four push buttons, a TSOP1738 infrared receiver, and an RS232 interface via MAX232. The software is written in C using avr-gcc and avrdude. It sends button identifiers to the serial port upon activation.
Parts used in the AVR Terminal Project:
- HD44780 compatible LCD controller
- 8 multiplexed LEDs
- Four push buttons
- TSOP1738 infrared remote receiver
- MAX232 chip for RS232 interface
- AVR microcontroller
description (hardware)
Above and below you can see the terminal.
The LCD display is represented by the connector X1. It has a HD44780 compatible LCD controller and I’m using the 4-bit interface to send data to the LCD controller.
The LED’s are multiplexed. I’ve seen the circuit somewhere in the web. It is possible to connect 12 LEDs with only 4 tristate ports with this circuit. You can address the LEDs setting 1 port high, 1 port low and 2 ports to high impedance. I’ve only used 8 LEDs because of space problemes in the aperture.
The blue points on the photo are four push buttons.
On the left side I’ve inserted an infrared remote receiver (TSOP1738) so that it is possible to telecontrol the computer.
Additionaly you can see the RS232 interface built with and max232 and the connector X3.
Connector X2 is used for incircuit prgramming.
schematic (drawn with gschem)
description (software)
The software is written in C. I’ve used the avr-gcc compiler and avrdude for programming.
If you press a pushbutton the terminal sends an “K”, the number of the button and a newline character.
For more detail: AVR terminal for serial port using TSOP1738 microcontroller
- How does the software respond when a pushbutton is pressed?
The terminal sends a K character followed by the button number and a newline. - What type of LCD controller is used in this design?
An HD44780 compatible LCD controller is utilized. - Can the system be controlled remotely?
Yes, an infrared remote receiver allows telecontrol of the computer. - How many LEDs are connected in the circuit?
Eight LEDs are used due to space constraints in the aperture. - Which compiler is used to write the software?
The avr-gcc compiler is used to write the C software. - What tool is used for programming the device?
Avrdude is used for programming the microcontroller.
