Computing stuff tied to the physical world

Meet the JeeBoard

In AVR, Hardware on Sep 2, 2009 at 00:01

I hate wires. Wires to power up stuff. Wires to transfer data. What a mess.

I just want to try out physical computing ideas on my desk, next to my (wireless) keyboard and my (wireless) mouse – while exploring the possibilities of hardware + firmware + software running on my “big” computer.

So here’s to scratching my own itch: meet the JeeBoard – a little 8×10 cm unit with no strings attached – heh ;)


A first mock-up with real parts, here still using a green JeeNode v2:


On the left, a couple of demo plugs have been inserted. Those that use I2C can be daisy-chained.

One port is permanently hooked up to an I/O expander chip with 6 digital I/O lines for the mini-breadboard, 2 LEDs, and 2 pushbuttons. The on-board battery pack provides 3.6V with NiMH or 4.5V with alkaline cells.

The little overhanging board on top of the mini-breadboard “feeds” 8 wires into the center of the breadboard: +3.3V, ground, and the 6 general-purpose I/O lines.

I’m going to mess around with the layout a bit and explore some actual hookups before designing a real PCB for this. But even just looking at the mockup makes me want to start trying out stuff with it. Wireless, of course!

  1. great idea ! i miss an lcd and an usb-port on the jeeboard. batterie pack , i think is not necessary . it takes too much place on the jeeboard which could be used by by another things. the battery pack could contact by a short wire, so there is the possibility to connect a power supply. kind regards thomas

    • Forgot to reply about USB: my suggestion is to use the USB-BUB, or any other FTDI-compatible plug or cable which is set to work with 3.3V signal levels. Or replace the JeeNode by a JeeLink. Both let you connect via the serial port and supply power through that same USB connection.

      I leave two BUBs permanently plugged in and I connect my various JeeNodes to the 6-pin headers as needed while developing and trying out stuff. It’s cheaper, and just as effective for me.

  2. Good points. I’m exploring the LCDs – could use an I2C I/O expander and tie it to any standard LCD in 4-bit mode, but there are more options and the whole thing has to run on 3.3V, preferably. It would be nice if it can be used with the new LiquidCrystal library in the Arduino 0017 IDE.

    The battery pack is actually a crucial part of this setup. What you’re after is equally important, but is for a different range of usage scenarios. The JeeBoard above, as I see it, is for untethered operation – and for experimentation in that context.

  3. A flat 3.7V LiPo battery like the ones Pollin is selliong might be a good alternative to the 3xAAA.

    It could be placed on the bottom side of the cardboard or between the cardboard and the breadboard. The saved space could be used for more on-board components, a larger breadboard, or to make the whole thing a bit smaller.

    • Interesting, and cheaper than most LiPo’s I’ve seen. Though I’d probably want to add a little charging circuit with such a solution, using the FTDI power as input. LiPo’s are finicky – I don’t even know whether they can be sent in a regular paper mail bag. They do hold their charge well over a long period of time.

      I’d rather use AA’s than AAA’s, more common and more power. But not three of them, so the other option I am considering is 1x AA plus a boost regulator – but that loses some of the simplicity.

      As for the space… one idea is to mount the optional LCD on top of the battery, maybe even a 128×65 pixel graphic one (I have one which does I2C @ 3.3V, reflective / no backlight).

      And I’d rather not make this thing too small – it’s good to have something sturdy and stable to act as “base” for other things, yet still small enough to be mounted on say a little robot. The JeeBoard is not the one-and-only board that can be done. Maybe later we add a little brother with LiPo or coin cell, once the power drain including wireless is really low?

      Power, display, proto area, pinouts, dImensions, expansion: so many choices, so many trade-offs!

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