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Thursday, 05 March 2015 23:29

Arduino based Electronic Queuing System

Queue calling system

This is a Queuing System project requested by a clinic asistant which allows the doctor enter number from a keyboard and display it on a 32x16 LED panel.

This project uses two Arduino, the first Arduino functioned as a SENDER which included a PS2 keyboard and a mini LCD for number input. While the other Arduino is functioned as a RECEIVER which will trigger a "ding-dong" tone and display number on the 32x16 LED panel.

The SENDER uses a PS2 keyboard instead of USB keyboard, USB keyboard will cost higher since it require a USB host shield. You should get a Matrix keypad (please use google translate) in case the PS2 keyboard is not available in the market.

These two Arduino (SENDER & RECEIVER) is connected via a CAT5e network cable, the CAT5e cable provide power to the RECEIVER and also transfer data between two Arduino.

What you will learn from this project

This project is not too difficult, upon successful completion of this project, you should able to:

  1. Built your own DIY Arduino without using the Arduino development board
  2. Using 8MHz internal oscillatior & eliminated the uses of 16 MHz crystal
  3. Serial communication between two Arduino
  4. Connect a PS2 keyboard for user input
  5. Control a Hitachi HD44780 compatible LCD
  6. Trigger a ding-dong reminder tone
  7. Driving a 32x16 Dot Matrix Display LED panel
  8. Monitor serial data while blink the Dot Matrix LED without delay


Materials for SENDER

  1. ATMEGA328 microcontroller
  2. PS2 Keyboard
  3. 10K resistor
  4. 0.1uF decoupling capacitor
  5. 100uF decoupling capacitor
  6. Printed circuit board
  7. 1602 LCD screen
  8. 2.2K resistor or resistor 6.8 K
  9. 5V 2A power adapter
  10. RS232 serial port header (DB9 male and female each one)
  11. Some wire


Materials for RECEIVER

  1. ATMEGA328
  2. Printed circuit board
  3. 10K resistor
  4. 0.1uF decoupling capacitor
  5. 100uF decoupling capacitor
  6. 32x16 Dot Matrix LED Display panel
  7. RS232 serial port header (DB9 male and female each one)
  8. 470 ohm resistors
  9. 8021-2 ding-dong doorbell IC
  10. 2W or 3W amplifier board + Mini Speaker
  11. Some wire

Arduino Software Libraries

You must have the following software libraries install on your computer:

Freetronics dot matrix display library: Driving Freetronics 512 pixels (32 × 16 layout) matrix LED display

TimerOne Library: Use with Freetronics dot matrix display library to configure 16bits hardware timer

PS2 Keyboard Library: An Arduino library for PS2 keyboard

LCD Monitor Library: Arduino LiquidCrystal dirver based on the Hitachi HD44780


Circuit diagrams and source code download

There are two folders (Queue_calling_system_Sender and Queue_calling_system_Receiver) inside the ZIP file, download and extract it to Arduino sketch folder. After that upload the Queue_calling_system_Sender.ino & Queue_calling_system_Receiver to the two Arduino respectively.

Electronic Queue Display System



This is a homemade Arduino (DIY Arduino) , it uses the 8MHZ internal oscillator as the clock source and require very few components. Resistor R3 is used to control the contrast , its resistance can be varies from 2.2K ohms to 6.8K ohms, it is recommended to use an 10K adjustable resistor to test the contrast before selecting a resistor. I have 20 sets mini LCD screen,  most of them can use the 2.2K ohm resistor for contrast control, however several of them have to use 6.8K ohm resistor.

R3, LED + and LED- is soldered directly to the PCB in order to reduce the wire connection beween the Arduino & mini LCD screen

Sender PCB

Sender Printed Circuit Board



The RECEIVER also using an 8MHZ internal oscillator as the clock source,  its design is very similar to SENDER with additional 470 ohm resistor and a 8021-2 ding-dong sound effect IC near to the pin 28 of ATMega328 .

The 8021-2 ding-dong sound effect IC is not able to drive a 3W speaker since its output signal is very weak, and therefore it must connected to a mini-amplifier.

I will not talk much about 32x16 Dot Matrix Display panel, please visit here for more details.

Receiver PCB

Receiver Printed Circuit Board


8021-2 ding-dong sound effect IC

The 8021-2 is a ding-dong sound effect generator IC produced by LSI CMOS technology. With built-in RC oscillator and digital envelope circuits, minimal external components are required.

M8021 Ding Dong Door Chime


Keyboard functions and instructions

Keyboard function


More photos


Sender Front

Sender Back

Complete Set Front

Complete Set Back


Read 15661 times Last modified on Sunday, 17 May 2015 21:35