How-to: The Bus Pirate, Universal Serial Interface

November 19, 2008 by Ian 60 Comments

UPDATE: New firmware with JTAG and more

We’re always excited to get a new chip or SIM card to interface, but our enthusiasm is often dampened by the prototyping process. Interfacing any chip usually means breadboarding a circuit, writing code, and hauling out the programmer; maybe even a prototyping PCB.

A few years ago we built the first ‘Bus Pirate’, a universal bus interface that talks to most chips from a PC serial terminal. Several standard serial protocols are supported at 3.3-5volts, including I2C, SPI, and asynchronous serial. Additional ‘raw’ 2- and 3- wire libraries can interface almost any proprietary serial protocols. Since this has been such a useful tool for us, we cleaned up the code, documented the design, and released it here with specs, schematic, and source code.

Continue reading “How-to: The Bus Pirate, Universal Serial Interface” →

Gift Card Electronics

November 11, 2008 by Kimberly Lau 28 Comments

Gift-giving season is upon us, and it’s time for people to start panicking about what to give to their friends and families. Gift cards have gained in popularity over the years, as companies count on people to forget to use them. But how about gift cards that do more than store a token amount of cash? Best Buy is now selling a gift card that doubles as a speaker. It has a mini headphone jack that’ll plug into any audio player. You only need to spend fifteen dollars to get it. Target’s gone all out, with a gift card that is also a 1.2 MP digital camera. It comes with a USB cord and driver disk, and there’s even one with a 64MB USB flash drive. We’re very interested to see if these will take off, and what people will do with them once the cards are used up.

[via Gizmodo]

How-to: USB Remote Control Receiver

October 30, 2008 by Ian 126 Comments

Now that we listen to MP3s, and watch XVIDs or x264s, a computer is the entertainment center in at least one room of most homes. Unless you have a special HTPC, though, you’re probably stuck using the keyboard to pause, change the volume, and fast-forward through annoying Mythbusters recaps. PC remote control receivers range from ancient serial port designs (who has one?) to USB devices not supported by popular software. In this how-to we design a USB infrared receiver that imitates a common protocol supported by software for Windows, Linux, and Mac. We’ve got a full guide to the protocol plus schematics and a parts list.

Continue reading “How-to: USB Remote Control Receiver” →

Parts: 3.5mm Stereo Audio Jacks

October 13, 2008 by Ian 21 Comments

3.5mm stereo connectors for headphones and microphones are almost mandatory for audio projects. X1 (left) is a simple plug with connections for the audio channels (pin 2,3), and ground (pin 1). X2 (right) has pass-through contacts (pin 2,3) that divert audio to an internal speaker when headphones aren’t connected.

Here’s a breakdown of the audio connectors illustrated above. Continue reading “Parts: 3.5mm Stereo Audio Jacks” →

Parts: MicroSD Memory Card Holders

October 6, 2008 by Ian 23 Comments

SD cards add cheap persistent memory to your project, but the holder takes a lot of board space. A smaller option is the microSD flash format. MicroSD cards are compatible with regular SD cards, and most come with a free adapter. We looked at four holders for our mini web server. Which should you choose? Read about our experience below. Continue reading “Parts: MicroSD Memory Card Holders” →

How-to: Networked Graffiti Wall

October 2, 2008 by Ian 22 Comments

[youtube=http://www.youtube.com/watch?v=G8KprTVbHD4]

Wondering what we did with our web server on a business card project from last week? It’s powering a giant LED graffiti wall. Animations can be user-submitted using the online designer. You can watch a live feed of user animations as well. The online interface runs on the Google App Engine for maximum scalability and resilience.

In today’s How-to we cover all the ins and outs of building your own networked graffiti wall. Continue reading “How-to: Networked Graffiti Wall” →

Parts: 0.1uF Decoupling Capacitors

September 29, 2008 by Ian 30 Comments

Most ICs need to be decoupled from their power supply, usually with a 0.1uF capacitor between each power pin and ground. Decoupling is usually used to remove noise and to smooth power fluctuations. Every project will need a few decoupling capacitors; our mini web server project has three ICs that require a total of 11. This can be an expensive part to buy in singles, so it’s crucial to stock up online. Read more about our favorite bulk through-hole and surface mount decoupling capacitors after the break. Continue reading “Parts: 0.1uF Decoupling Capacitors” →