Computing stuff tied to the physical world

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Meet the new Room Board v2

In Hardware on Nov 28, 2010 at 00:01

For some time now, the Room Board kit has been outfitted with a new PIR sensor:

It’s nicely low-power, but unfortunately it has a pin-out which differs from the ELV model, even with 3 pins!

So I’ve decided to make a new Room Board v2, which drops support for the 8-pin ePir to allow the new PIR sensor to be mounted in two different ways.

Here’s the board, with a solder drop already applied for the SHT11 (much easier to solder it in that way):

Dsc 2345

Things have been moved around a bit, but the basic setup hasn’t changed. The 3 pins in the top left are still for the ELV PIR, and the 1-wire DS18B20 option is still there (with fixed pinout, yeay!).

Here is the board with SHT11 and LDR soldered on:

Dsc 2348

And here are the two ways to attach the new PIR sensor:

Dsc 2350 Dsc 2349

That second setup is the most compact, but also the most inconvenient one if you ever need to make changes or reach the headers. Note that the PIR pins were soldered in as far out as possible, and that the LDR was bent sideways a bit:

Dsc 2354

I would advise to use the first setup where possible.

Having said that, here’s a complete Room Node with the (relatively) “compact” layout:

Dsc 2355

Bit of a hodge-podge, but that’s what you get when everything is kept modular.

  1. Looking at the bare PCB, http://jeelabs.org/2010/11/dsc_2345.jpg I see you have several 90 degree bends on moderately small wires (8 mil?) It seems like your PCB vendor does a good job, but just for what it’s worth, I was always taught to avoid 90 degree turns when possible, due to “acid traps” during etch that would eat away some width on the inside corner, in the worst case causing an open trace.

    JBeale 28 November 2010 at 5am

    • Thx – yes, traces are usually 8 mil. All boards are electrically tested, so I hope they catch all these kinds of problems before the boards get sent out. I occasionally come across rejected boards in a panel, but not often.

      jcw 1 December 2010 at 9pm

  2. Is there any restriction concernibg the distance beraden the jeenode and the roomboard? Ie can I use 5meter long leads for example?

    Mars 1 December 2010 at 9pm

    • You might get away with it. I’ve recently found out that the SHT11 can be used over very long distances (but you need to add a capacitor over its power supply pins). The PIR and LDR can probably be used ok, if you use twisted-pair or shielded cable.

      You’ll have to try it out, though.

      jcw 1 December 2010 at 9pm

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