Computing stuff tied to the physical world

Smaller still?

In AVR, Hardware on Sep 9, 2009 at 00:01

Now that the JeeLink is a reality, and SMD has become an option, I’m already wondering how far to take this…

Because, well, there’s this neat USB stick case available:


I suspect that the same FTDI + ATmega + RFM12B as on the JeeLink can be fitted in there, but at the cost of omitting all expansion. No ports, no headers, no reset, nothing – but nevertheless an Arduino / JeeNode / JeeLink compatible unit.

There may even be room for a few Mb of flash memory. So this could be used as central interface to a PC/Mac, and it could collect data while the computer is off – as long as the USB port is on (a powered hub perhaps).

Would it make sense to create a separate unit for this? Just for the wow factor? Let me know, please…

  1. I like the look of the small usb enclosure.

    To me it would make sense to put everything in there without the I/O, more of a JeeBridge/gateway, a device to connect to your sensor network.

    I can also see the benefits of the Jee-link though :) (another product to the mix? lol)


  2. Yes, it is worth to do for a data collector. No I/O needed at this point but indeed memory. Thomas

  3. If it is possible to use the RFM12B for OOK decoding, this would make a nice weatherstation data collector. So far I only tried your basic samples with the JeeLink… Trying OOK decoding for Kaku is next on my list ;)

    • This could be tricky, but it would be great if you can solve it. You’ll probably need to continuously poll the RSSI info in the status register, so it might be hard to use a single RFM12B for both FSK and OOK reception.

      Another way to solve it could be to create a packet relay: a dedicated JeeNode which does the OOK decoding and then re-transmits all properly received data as FSK packets. The decoding can then be done with a small OOK receiver, or even two if you want to handle both 433 and 868 MHz.

      I’ll be very interested to hear about your progress!

  4. Hmm, I think you can use headers with a smaller pitch. Use both side’s of the circuit board and leave out the extra voltage and ground pins that is available on every port. So more like one total expansion port with all 4 aio and dio ports, vcc and ground. Make’s 10 pins used. I really like some extra leds on the board. Like the pin 13 on the arduino or a led near the INT / IRQ of the RF12b to see data packets comming in and out

    • Are you referring specifically to this smaller version, or JN’s/JL’s in general?

      The reason for the current port design is the use of plugs. Smaller pitch would make it harder for people who want to use through-hole components for easier soldering.

      There are RX/TX LEDs on the JeeLink, but not on the JeeNode which must also work in (very) low-power scenarios (the USB-BUB interface has a LED though). An activity LED could be an idea for USB-connected units, not for the JeeNode (power use again). Note also that the upcoming “Blink Plug” will make it easy to add LEDs via a port connector.

      Each of these units is a fairly tricky trade-off, and evidently one size won’t fit all. The concept of “ports” was added because I found myself always out of power and ground pins on an Arduino.

      I’ll keep the activity LED idea in mind. As for a single connector – what type of connector did you have in mind? Would an extra daughterboard with such a connector on top make sense?

  5. Let me put it this way. I almost placed an order yesterday. But then I saw that is would have been almost 60 euros… If you can get it to say, 40 or if I’d get two nodes for the 60. This would be a steal. Wireless is awesome… but I’d only play around with it anyways…

    • Two JeeNode kits + two sets of JeePlugs + one USB-BUB and you’re all set to have quite a bit of wireless fun for € 59, no?

  6. Where did you buy/get the USB case from, if you don’t mind?

  7. Hi JC! How are you? This is definitely a good idea. I’m planning to plug a JeeLink to the PC just for connectivity, I will not use the ports, just the radio module.

    • Salut Pedro – all is well here, thx :)

      Yes, that’s my thinking too. Remote nodes often need all sorts of connectivity and expansion, for which there are ports & plugs. But in the context of a single computer collecting (or controlling) such a group of JeeNodes, the central unit does not always need to be tied to sensors or actuators.

      The JeeNode and JeeLink wouldn’t be dropped, so this would merely add an extra option.

  8. I’ll be waiting for one of those that go inside the transparent box! Consider this as a pre-order ;-)

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