How to increase storage on TP Link TL MR3020 with

The TP-Link TL-MR3020 N150 3G/4G Travel Router is a very small device with a size of 74mm x 67mm x 22mm, it has only 4MB flash and 32MB memory. The router have about 428KB (67%) space available after installing OpenWRT Barrier Breaker 14.07, you may encounter shortage of storage when installing certain extensions due to limited of router space. 

By employing OpenWrt's extroot, you can expand the storage capacity of your root file system using the additional space of an added storage device.

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.

This project provides step by step approach to driving a Dot Matrix Display (DMD) Panel with an Arduino. The DMD is a 512 pixels single colour LED display arranged in 32x16 layout, a 16 pin (2x8) IDC connector is used to interface with Arduino.

In order to drive the 32x16 Dot Matrix Display Panel from Arduino, the DMD library for Arduino is required. You can download it from Freetronics GitHub.

The Freetronics DMD library is able to write letter and text on the display board with limited function, variable string and text centering is not supported. Yeah! now you can use my code to write variable string on the display board and centering it horizontally.

Updated: DMD2 library is released, this library is currently in BETA release.

Sunday, 08 February 2015 21:09



发送器连接了一个PS2键盘来完成输入,当然也可以使用USB键盘,不过必须添加一个USB Host Shield,这样将会增加成本。如果没办法取得PS2键盘,建议使用矩阵键盘。发送器也应用了一个小型LCD,用于显示编号,当然还能显示更多的相关资料。


Sunday, 12 October 2014 15:12

Using HEF4094 Shift Registers with Arduino

I have many seven segment modules in my hand. Each module consists of 5 digits and each digit is controlling by individual HEF4094 shift register. As shown in figure above is the seven segment module.

HEF4094 is an 8-stage serial shift register. Data is shifted on the LOW-to-HIGH transitions of the CP (Clock) input. The product data sheet is available here.

HEF4094 operates over a recommended VDD power supply range of 3 V to 15 V referenced to VSS (usually ground). There is also 74HC4094 available which operates at 2V to 6V.

I own a TP-Link TL-WR1043 V2.1 wireless router, I would like to test if it is able to run on OpenWRT or DD-WRT. it is first tested on OpenWRT, DD-WRT later, so far it has been working flawlessly for me.


About TP-Link TL-WR1043 V2.1 Wireless Router
TP-Link TL-WR1043 V2.1 is a 300Mbps Wireless N Gigabit Router, it has more memory (64MB) compared with the TL-WR1043 V1.x. Here is the comparison:

HW Version










Atheros  [email protected]









Atheros[email protected] 64MB








此教程使用一个TP-Link TL-MR3020 3G/4G无线路由器来打造简单的无线广告机。目标是提供一个免费热点(hostpot)让公众无线上纲同时弹出hostpot提供者的广告(称之为Splash page 或者Landing page)。

TP-Link TL-MR3020的厂家固件(Firmware)功能有限,不能安装第三方软件包,因此,固件必须升级至OpenWRT,然后再安装NoDogSplash

虽然这里是使用TP-Link TL-MR3020为教题,一般支持OpenWRT的路由器也是适合的。 

This is a guide on how to setting up a simple wireless hotspot using a TP-Link TL-MR3020 3G/4G Wireless N Router installaing with NoDogSplash. The goal is to provide a free hotspot with a splash page to advertise who is providing the hotspot, it should work as well for other OpenWRT supported router.
Friday, 04 July 2014 13:54

Arduino based RGB Matrix LED tester

Arduino based RGB Matrix LED tester

This is a very simple Arduino project which control the 16x32 RGB LED Matrix Panel via an 16pin IDC cable. The Arduino will continuously sending 5 set colours (Red, Green, Blue, White, Black)  to the LED Matrix Panel that allow the technician to find out which part of the LED Matrix Panel is malfunction.

Wednesday, 18 June 2014 23:34

Removing Applications from Raspberry Pi

You might want to remove some applications to free up some space on SD card. Use the following syntax to uninstall a program
sudo apt-get –purge remove APPNAME #replace APPNAME with the name of the app you want to remove
An example to remove Scratch program 
sudo apt-get remove scratch
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