Full featured security lock demonstration

[Arshad Pathan] let us know about his latest project, a modular code lock that can be adapted to many different situations.

The user interface is made up of a character LCD screen and a 3×4 keypad. For this example [Arshad] is using a stepper motor as the locking mechanism. When the board is first powered up it runs the stepper in one direction until receiving input from a limiting switch. In this way, the microcontroller calibrates itself to ensure the lock is in a known position. From there it waits for user input. An unlocked door can be locked at any time by pressing the * key. Unlocking requires entry of the correct password. And a password can be changed by entering 9999 (followed by the old password when prompted).

In the video after the break [Arshad] does a great job of demonstrating the various modes which he has programmed. This stands on its own, but we always love to have more details so we’ve asked if [Arshad] is willing to share a schematic and the source code. We’ll update this post if we hear back from him.

Update: [Arshad] sent in a couple of schematics which can be found after the break.

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LCD backpack: from Arduino board to homemade pcb

[Kaushlesh Chandel] prototyped a few projects on his Arduino that use an HD44780 Character LCD. Wanting to keep these projects in one piece, but not sacrifice his Arduino board, so he etched his own LCD backpack that is Arduino compatible. If you’ve never made it past the Arduino board to build a module that only uses the parts you need for a project, this is a great source of inspiration for you to give it a try.

The design that [Kaushlesh] drew up is quite simple. It connects directly to the single in-line header of the character LCD. It looks like he’s using the 4-bit mode for addressing that display, which leaves you with quite a few pins (both digital and analog) to work with in the future. The important components rolled into his design are the chip itself, an ATmega8/168/328, the crystal to make sure it is running at the correct speed for Arduino timing, and a trimpot for adjusting the contrast on the display. The final feature you’ll want to be sure to include in your own design is a pin header for programming the chip via an FTDI cable.

Never etched your own PCB before? Give our PCB fab tutorial a try.

XBMC controller is an all-in-one usb solution for HTPCs

On the original Xbox, XBMC was a software-only solution (assuming you had a chipped or soft-modded console). That’s because the Xbox was already meant to connect to a television and work with an IR remote control. Now that the XBMC software has transitioned to focus on a wider range of hardware, it may be more complicated to get the same functionality on an HTPC. Realizing this, [Dilshan] developed a USB connected XBMC controller that features an IR receiver, character LCD, and a rotary encoder with two buttons.

As long as your HTPC has a way to connect to the audio and video inputs on your TV, this should take care of the rest of the presentation. LCD screens were popular with XBMC from very early on because modchips included an interface. Because of this, XBMC is already setup to provide navigation and media information this way. So you can use XBMC for audio playback without needed to have your TV turned on. Add to that the ability to control your box with either  a remote control or the navigation tools on the front bezel and you’ve got a winning solution.

You can download an archive that includes all the info about this device over at the project repository. For your convenience we’ve embedded the schematic and PDF description of the project, which we found in that package, after the break.

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Wireless 4 Channel Temperature Monitor From Arduino Libraries

Say what you will about the Arduino platform but there certainly are a ton of libraries one can choose from. That is precisely what [Dan Julio] set out to do when building his slick looking 4 channel temperature monitor. The monitor consists of an Arduino RBBB, 2×16 character LCD and four DS18B20 1-wire digital thermometers. [Dan] also includes a bluesmirf to interface with an OS X monitoring program.  Using libraries for the Bluetooth, LCD, and temperature monitors the Arduino code is only about 200 lines, and pretty easy to follow. Check out more at [Dan]’s site.

If you’d like more temperature sensor projects check out this mug or this PIC based monitor or perhaps you’d like to keep it in the Atmel family.

Driving USB peripherals with Arduino


Circuits@Home have managed to host a USB keyboard with an Arduino and display the keyboard inputs on a character LCD. This uses the USB host shield we covered in August. That host shield includes a MAX3421 which is used here to drive the character LCD.

The control code for the keyboard ends up being fairly simple. The keyboard is polled for entries. The HID input is then examined and converted to ASCII codes for use with the LCD screen. This could make for an excellent controller or debugger for embedded systems. The Arduino, shield, and LCD could be integrated into the keyboard itself with an I/O port for connecting to your project. Commands can be typed out and sent through the I/O port when enter is pressed, with feedback displayed on the screen.

The example code provided with this project lays out the framework for hosting peripherals. We’re looking forward to more projects, and code libraries that take advantage of this new functionality.

Parts: 4×20 VFD character display (NA204SD02)


Futaba makes vacuum florescent character displays that can be used as a drop-in replacement for common character LCDs. VFDs have a wider viewing angle, and generally look cooler.

Futaba’s character displays can be interfaced using the standard 8-bit or 4-bit parallel LCD interface, or a simple two-wire protocol. The protocol type is set by resistors on the back of the display, so it’s not particularly easy to change without a hot-air rework station. Today we’ll demonstrate a serially-interfaced VFD using the Bus Pirate.

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