Computing stuff tied to the physical world

JeeLink build woes

In AVR, Hardware on Aug 16, 2009 at 00:01

Ok, I’m back. The Jee Labs blog resumes…

This first post is a progress report on the JeeLinks. Here are three partial builds (the bottom one has some hand-soldered parts, the rest use reflow soldering):

DSC_0432.jpg

I had to remove some solder bridges from the FTDI chips, but apart from that everything looks pretty tidy now. The JeeNode-based reflow controller is working very nicely.

Here are a couple of extreme close-ups:

frame1.jpg

frame2.jpg

frame4.jpg

frame5.jpg

Unfortunately, I’ve not been able to get any of these boards working so far. The FTDI chip ought to be visible as a serial USB port, even if the MPU isn’t working properly, but it isn’t showing up.

I’m probably missing something but for now it’s bad news. I’ll continue debugging this, of course…

  1. Welcome back! I would toss in a 100nf decoupling capacitor on VBUS and 3V3OUT, and probably also a bigger one (10uF or smth.) on VBUS.

    Apart from that it looks ok to me..

    Cheers,

    -Marius

  2. Hi again,

    Another idea: It’s possible to reprogram the EEPROM of the FTDI chips and change things like device ID, device name etc. This could be a nice feature to be able to auto detect JeeLink boards on the host side and not confuse it with a normal FTDI serial port.

    -Marius

  3. Welcome back Jean Claude, hope you had a great break!

  4. Hello Marius, Stephen – good to see y’all back as well.

    I’ve changed the 1µF to 1 10 µF, now on both sides of the VR. Since they are ceramic, I thought maybe no extra 0.1µF decoupling is needed?

    As for reprogramming the FTDI, yes that could be a good idea for later – especially once I get to work on some new code to make it easier to manage/upload stuff to JeeLinks and JeeNodes. With multiple units connected, default serial port names are a bit awkward – though the Arduino IDE 0017 helps by supporting multiple serial consoles at once, IIUC.

    I’m still debugging the SMD boards – also ordered a magnifying glass with proper lighting.

  5. You have to explain how you use the reflow :)

  6. I’m basically following what others have done using various tips on the web, such as this one: http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=59

    See also all the reflow posts on this weblog: http://news.jeelabs.org/?s=reflow

    I’ve done at least a dozen reflows by now, they all worked just fine on my 700W grill with up to 4 JeeNode-size boards. I’m still using leaded solder though, will soon switch to lead-free and raise the temperature by some 20°C.

    The main issue is to apply a consistent (small!) amount of solder paste. I’m looking into various stencil options.

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