Planet Arduino

Over on the Spectrum web site, [Dale] — a relatively new ham radio operator — talks about his system for sending text messaging over VHF radios called HamMessenger. Of course, hams send messages all the time using a variety of protocols, but [Dale] wanted a self-contained and portable unit with a keyboard, screen, and a GPS receiver. So he built one. You can find his work on GitHub.

At the heart of the project is MicroAPRS, an Arduino firmware for packet radio. Instead of using a bigger computer, he decided to dedicate another Arduino to do everything but the modem function.

You can probably figure out the rest. A $10 GPS, a battery pack, a charge controller, and a few user interface parts like an OLED screen and a keyboard. In addition, there’s an SD card to store messages.

Of course, we couldn’t help but notice that our cell phone has a keyboard, screen, GPS, and storage. We might have been tempted to work out a way to connect the radio to it by Bluetooth. But we have to admit the little HamMessenger setup is cool-looking and probably lasts longer on a charge than our phone, too.

Them kids with those Arduinos don’t know what they’re missing. A serial connection is just too easy, and there’s so much fun to be had with low bandwidth modems. [Mark] made the MicroModem with this in mind. It’s a 1200 baud AFSK modem, capable of APRS, TCP/IP over SLIP, mesh network experimentations, and even long-range radio communication.

As the MicroModem is designed to be an introduction to digital wireless communication, it’s an extremely simple build using only 17 components on a board compatible with the Microduino. The software is built around something called MinimalProtocol1, a protocol that will be received by all other listening stations, features error correction, and automatic data compression. There’s also the ability to send TCP/IP over the link, which allowed [Mark] to load up our retro site at a blistering 1200 bps.

The code is extremely well documented, as seen on the Github for this project, with board files and even breadboard layouts included. [Mark] has three PCBs of his prototype left over, and he’s willing to give those out to other Hackaday readers who would like to give his modem a shot.