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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.
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.
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.