Finding an Active TX Pin on Cheap GPS

Twenty Euros will score you a small, self-contained GPS keychain. Crack that case open and you can have a lot more. [j3tstream] explored the guts of the thing and found that the NMEA data can be streamed out of the TX pin on the GPS chip.

First off, check out that miniscule GPS antenna module, crazy! But we digress. For testing purposes the asynchronous UART of the GPS was probed, proving that the data can be acquired. From there [j3tstream] moved to an Arduino Pro Mini with an SD card for data logging. The uC is powered from the GPS board but this will quickly exhaust the stock battery so [j3tstream] swapped it out for one from an old cellphone.

That little dot-matix LCD that comes with the unit also caught our eye. If you can hack a headless interface for the GPS that could be repurposed for your next project. May we suggest a wearable gaming project for it?

A history of SparkFun prototypes


If you haven’t checked out SparkFun Electronics’ prototype collection yet, you’re missing out. They unearthed many of their old prototypes and published them to show what kind of mistakes could be made. You’ll see plenty of errors and get hints on what to look for while developing your own hardware. This pairs well with their Design for Manufacture post. Along with the pile of broken board iterations, they also walk through how the company developed. Finally, they specifically cover the individual iterations of the BlueSMiRF.

One of the interesting modules in the gallery that never saw full release was the SparkFun Toys line pictured above. The individual units used the standoffs as the power and data bus. The four posts were arranged so they could only be connected in one orientation: power, ground, TX, and RX. It’s an interesting idea that seems like it might be worth exploring further. SparkFun says that it worked fine, but didn’t feel they had the resources to market it to the intended audience.