Computing stuff tied to the physical world

Assembling the JeeNode v5

In AVR, Hardware on Sep 26, 2010 at 00:01

New JeeNode means: new build instructions.

Here goes. A long description of how to go from this:

Dsc 1973

… to this:

Dsc 1970

Make sure you’ve got a nice soldering iron (not too hot, not too large) and some solder wick to remove solder in case you need to back up a bit to fix things. The JeeNode printed circuit is very sturdy and can handle a lot of abuse, but some traces are thin, so be careful and don’t apply too much force.

Components are soldered on from lowest to highest profile, because then you can turn over the board and push on it to get each component snugly against the board as you solder it. So let’s start with the resistor:

Dsc 1974 Dsc 1975

Once you’re satisfied with the soldering, turn it over and snip off the leads:

Dsc 1976 Dsc 1977


Next, the four small yellow ceramic caps – which you can either pull out of the cardboard strip or just cut free:

Dsc 1978

The fifth capacitor is a small black one, and the key here is that it is polarized, so you have to put it in the right way around – like this (the long lead is “+” and should be on the right-hand side):

Dsc 1979 Dsc 1980

Next, the 3-pin voltage regulator chip. Again, make sure it goes in the right way:

Dsc 1981

New on this board is the diode. It’s slightly tricky. First, bend the leads as follows, and then very gently “wiggle” it into the two holes:

Dsc 1982 Dsc 1983

As you will see, it barely fits – the holes are almost too small. But it does fit. Don’t push too hard, just wiggle until the diode is all the way in, almost against the board. Then turn it over, solder it, and snip off those thick soft wires.

UPDATE – the diode is no longer included in the JN5 kits (reason). Please use the solder jumper on the other side of the board instead, or your JeeNode won’t work!

Next step is the IC socket. Put it in the right way (see the notch on the left?) and solder down only two opposite corner pins at first:

Dsc 1984 Dsc 1985

Now make sure the socket is completely flush against the board – not like this!

Dsc 1986

If there is a gap, re-heat the pins and press on the socket while the solder is molten. Until everything is ok. Then solder those remaining 26 pins.

It’s time to put the port headers in. These fit in holes which are slightly staggered – that keeps them in place as you turn the board over for soldering:

Dsc 1987

Put all the headers in, then turn the board over on a flat surface, so that the headers are flush with the board when you solder those 4 x 6 pins.

One last component is that orange resonator with 3 pins. For convenience, I always put it in with the “16 Mhz” readable from the outside. Once soldered in, snip off the pin ends, because they are relatively long:

Dsc 1990

Almost there now. The last bit is the wireless part. Put a small dab of solder on one of the RFM12B pads:

Dsc 1988

Then place the radio module on it and hold it down with one finger while heating the solder until it flows under the radio module. That will hold it in place as you solder the remaining pads:

Dsc 1989

The FTDI header is also a bit tricky. I use a flat 6-pin male header, because that way the pins come out at almost the same level as the board itself, which works well with a USB-BUB.

The trick is to use one of the middle pins to align everything, so I first put solder on one pin and the matching pad. Looks as if I’m one off here, but that’s because the header is flipped over before soldering:

Dsc 1991 Dsc 1992

With a bit of experience, you can get the pins just right by holding the header with your fingers and pressing it down while re-heating the solder. Otherwise use a little clamp. Continue only when the pins are well-aligned and flat on the board. Don’t heat them too long or the plastic will melt. Then, finish the remaining pins and you end up with something like this:

Dsc 1993

Now the ATmega chip. You have to be careful – the pins usually stick out a bit more than is practical with an IC socket (that’s to help automated equipment pick up such chips). So first bend those pins slightly closer together:

Dsc 1994 Dsc 1995

The way to do that is to place them on the table with the pins on the surface, and then push the chip slightly towards the pins. Then turn it over and repeat for the pins on the other side.

Once adjusted, put the chip in the socket (watch the position of that notch!). Careful … this is how not to do it!

Dsc 1996

Once properly placed, push down so the chip goes all the way into the socket:

Dsc 1997

Ok – last step now, promise. Strip the antenna wire a little, and solder it in place (I usually do it from below):

Dsc 1998

Then bend the antenna wire so it doesn’t get in the way. I usally fit it as follows:

Dsc 1999 2

That’s it. Congratulations with your new JeeNode!

  1. Hi jcw, wouldn’t it be a good idea to put the antenna right on the pcb itself? In the last pic above it is a bit dangling around. cheers, Jan.

    • Yes – this has been suggested before. I’d rather not change the dimensions of the board at this stage, so for the through-hole kit it will be a bit hard to find the board real-estate.

      It’s not as bad as it may seem. That orientation alongside the headers is easy to pick up and often works out ok in day to day use, in my experience. I’ll keep it in mind, though – thx.

  2. Great idea staggering the header pins!

  3. Just be careful when soldering that 6 pin FTDI male header, those brass pins conduct heat right up to your finger very very quickly if you happen to be holding the one you’re trying to solder!

    I have the scars to prove it! ouch

    I insist on learning the hard way!

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