Data Confirmation With RF Communications

October 18, 2010 by Mike Szczys 35 Comments

[Rafael] built a system that uses radio frequency for communications. The code he was using with the inexpensive receiver/transmitter pairs already had some error correction but from time to time an entire message would be missed by the receiver. He set out to make these RF communications more robust.

A little more than a year ago we looked at using these same transmitters with an Arduino. [Rafael] has a similar setup but since they are unidirectional he chose to use two pairs for bidirectional communication (each operating at a different frequency to avoid interference). On one end, a computer transmits data to the Arduino which is in a remote location. His confirmation protocol relies on a randomly generated message identifier. The computer will continually transmit the same message. The Arduino continually receives these messages, comparing them with the last successfully received message. If they match, it is considered a successful data transfer and the Arduino transmits a confirmation back to the computer which then starts transmitting the next message.

This isn’t an application-specific protocol. For demonstration purposes [Rafael] built a quick home automation setup that uses it to operate a house lamp.

IR Receiver As USB Keyboard

October 4, 2010 by Mike Szczys 12 Comments

[Arthur] built an IR receiver to use with XBMC. Because it’s software specific he identifies the device on USB as a keyboard, and passes the IR commands as keystrokes used by the popular media platform.

Normally, homebrew IR receivers would use LIRC, the Linux Infrared Remote Control software. But this method doesn’t require you to have that running. In fact, it doesn’t need any setup on the PC end of things. Any remote that uses the Sony SIRC protocol will work off the bat.

[Arthur] chose a PIC 18f2550 for the project. It is a popular microcontroller because it has built-in USB handling. We’re a bit skeptical of the hardware design though. We didn’t see specifically which IR receiver he’s using, but many require some type of filtering so check the suggested layout in the datasheet for your module.

All About VLF Radio

April 14, 2010 by Mike Szczys 20 Comments

If you’re interested in learning about Very Low Frequency communications take a look at what Larry has to offer on his site. He’s put together a guide to VLF receivers that is short enough to read and clear enough to understand with rudimentary knowledge of circuits. He builds a simple receiver as a working example and a high-powered transmitter that can put out over 2600 watts. Let’s face it, radio operators were the original electronic hackers. Get back to our roots and learn the ways of the transistor.

[Thanks Buddy]

Add IR Control To Your WiFi Router

September 29, 2009 by Mike Szczys 6 Comments

wrt54g_ir_receiver

[Craig] wanted to use Boxee on his TV but his computer was in a different room. He rigged up a rather dubious method of delivering the A/V signal (this is a hack in the most guttural sense). More interesting to us is his solution for a remote control interface. We’re familiar with building USB connected infrared receivers but [Craig] decided to patch one into the serial connection on his Linksys WRT54G router. Continue reading “Add IR Control To Your WiFi Router” →

Wireless BlinkM Control

January 10, 2009 by Eliot 5 Comments

blinkm

[John] has been working with several BlinkM RGB devices. He’s created a controller to talk to each of the BlinkMs wirelessly and change their behavior. The core is an old relay tester box used to test telephone circuits. Each of its four knobs are connected to the analog inputs on the Arduino. The signal is transmitted using RFlink devices. Each BlinkM is paired with an ATmega168 and receiver. The control box also has a switch to send the same signal to all of the devices at the same time. The transmit and receive code are available on his site. You can find a video of it embedded below.

Continue reading “Wireless BlinkM Control” →

Build Your Own GPS And GLONASS Receiver

October 4, 2007 by fabienneserriere 17 Comments

[superlopez] sent in this detailed article (mirrored here and here) which describes how to build a GPS and GLONASS (the Russian version of GPS) receiver. The resulting device is gigantic compared to one of those tiny bluetooth USB GPS units, but the ability to build one’s own receiver is one of those post-apocalyptic skills I sure would like to have. The creator of the article [Matjaz Vidmar] aka [S53MV] also has pages on Packet-Radio (PKT) transceiver improvements (PKT gets my vote for the best post-apocalyptic technology, and the only believable technology featured in the Transformers movie), and a more sophisticated homemade frequency counter than the one featured earlier this summer.

In 2005 we featured a from-scratch GPS receiver as well, thought the project site seems to be down. If your GPS unit just needs a better antenna, check out [Will]’s how-to from last year.