Saturday, January 17, 2015

Finishing this one up

Printed case view from the slicer.  I got lucky today, I was able to change the filament without having to disassemble the print head, small miracle.

Theory is, these will slide together and I'll add a little hot glue to hold it all together.  Real close to encasing this one in epoxy, but I'd like to find a way to cut down on static first.

Assembling the PCB didn't go quite as well as I'd hoped.  The CC2500 has a large(ish) crystal on the back (this is how they can sell for <$5).  I had to carve out a hole in the board, which required I add another jumper.  I knew I was going to route a slot, I just didn't realize how large it was going to end up being.

Here's a view of the completed board, with the separate lipo charger.  I usually mount the lipo unit on the same board, but I realized I could get this one really small if I did without.

Here's a view of the carving on the back of the board to allow the CC2500 to sit flush.

The CC2500 didn't work initially either.  I had to reheat all the connections, and the ones on the RFDuino.  Then I used a solder wick to remove excess solder.  After a few rounds, everything was working.  This just goes with the territory when you're hand soldering surface mount components.
I have an electric frying pan and solder paste, I may give that a try next.

And finally, most of my models since last January.


  1. Looks super cool Don!
    What kind of life do you get on this setup, I felt like my rfduino was running away with my battery

  2. There are tricks to using the rfduino, it needs to be in that ulpdelay
    state almost all of the time. It wakes on interrupt for anything ble
    That's at +4 db also.
    I'm at 4ma now. That's 26+ hours on a 110maH lipo. I think it's a
    big improvement since you aren't running two micro's. I need to
    measure the current again, I'm making no effort to put the cc2500 to
    sleep, so that might still be costing me.

  3. Either way, 26 hours on a battery that small is nice, I dont think too many things are in the 100mah range and dont need nightly recharging

    Looks really cool, now I want to play with my rfduino again!

  4. Power usage:
    21ma actively listening for dexcom packet
    3 ma "idle"
    Without the 2500 connected I can get down to 1.3 ma, so I'll have to look into getting the CC2500 to sleep. Already know it should be possible to get down to 0.6ma based
    on the Wixel.

    1. Final numbers: 21ma for <5 seconds every 5 minutes. Sleep the rest of the time at 1.6ma.