Wireless microcontroller/PC interface for $3

May 19, 2013 By 48 Comments

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Sending data from a microcontroller to a PC usually requires some sort of serial connection, either through fiddly on-chip USB, FTDI chips, or expensive radio ICs. [Scott] didn’t want to deal with this when creating a network of wireless temperature sensors, so he hacked up a few cheap 433 MHz radio transmitters and receivers to transmit data to a PC for about $3.

After sensor data is collected on a microcontroller and sent over radio, there’s still the issue of getting it into a PC. For this, [Scott] piped the data into the microphone port of a cheap USB sound card. We’ve seen this trick before both in the world of microcontrollers and loading programs onto a Commodore 64 via a cassette interface.

Once the data is sent into the sound card, it’s decoded with a a small Python app. Given the range and quality of the RF transmitters and receivers  [Scott] says it’s not an extremely reliable way to send data to a PC. It is cheap, though, and if you need to read sensors wirelessly on a budget, it’s hard to do much better.

Check out [Scott]‘s demo of his creation below.

Filed Under: Microcontrollers, radio hacks, wireless hacks Tagged With: , , ,

Getting an Arduino to control a wireless outlet

January 31, 2013 By 8 Comments

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[Reza's] methodical investigation of this remote controlled outlet let him patch in with an Arduino using a 433 MHz transmitter. This is a single-device unit, but the techniques used here should allow you to take control of wireless rigs that have multiple modules to control many devices.

We’ve seen some folks at our local hackerspace try to patch into the remote control itself. That used some type of weird button scanning (not just connecting a pin to ground or voltage) and didn’t pan out. [Reza] doesn’t even crack open the case of either of the units seen above. Instead, he goes straight for a wireless receiver he had on hand, using a logic analyzer to capture the signals coming from the remote.

Once he had a good snapshot of the signals sent when pressing the on or off button of the remote he set out to replicate it in his Arduino code. His function called setStateWithDelay takes three parameters: the transmit pin, the level (high or low), and a number of milliseconds to delay. Each signal calls this function many times, but working the bugs out is pretty easy; just capture the signal with the logic sniffer and compare to the stock remote.

Filed Under: Arduino Hacks Tagged With: , ,

Wireless hackerspace music control

October 12, 2011 By 8 Comments

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The crew at the Netherlands-based Bitlair hackerspace love their music, and have set up a digital jukebox for their workshop using mpd and fookebox. One problem that you run into with a bunch of different people working in one place is that everyone has their own distinct taste in music. The rhythmic “wub wub wub” of Dubstep might be great for some while leaving others trying to solder while simultaneously covering their ears. To ensure that everyone can exercise a musical veto (a la Empire Records) now and again, they built a Skipbutton which allows members to change what’s playing.

The button allows users to skip to the next song in the queue. as well as to control the volume of the space’s sound system. It uses an Arduino pro mini to run the show, sending signals to the mpd daemon using a 433 MHz transmitter. Bitlair is pretty large and they often spend time outdoors, so they had to ensure that the Skipbutton worked wherever they did. To do this, they built a Yagi-Uda antenna at the receiving end to ensure that the button functions no matter where it’s being triggered from.

Check out their wiki if you’re interested in making a similar system for your home or hackerspace – all of the code and schematics are available for the taking.

Filed Under: Arduino Hacks, wireless hacks Tagged With: , , ,

BPSK on 433 MHz European ISM band

August 3, 2009 By 10 Comments

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[WaveRider] is using a type of phase shift keying called BPSK to transmit digital sound and video for remote telemetry. Though a higher signal to noise ratio (SNR) is generally sought after with communications, legal limitations are imposed on total radiated power. To balance the two headed beast, he opted out on frequency shift keying due to binary shift keying’s ability to work with lower SNR. This adds the difficulty of properly reconstructing the digital signal at the receiver. A PLL based carrier regeneration circuit is used to reconstruct the signal. Using the Rabit2000 processor as the host controller on both transmitter and receiver, 96KB/Sec serial data is obtained. On the other side of the spectrum is the Homemade regenerative tube radio.

Filed Under: home entertainment hacks, misc hacks, wireless hacks Tagged With: , , , , , , , , , ,