Jee Labs Talk

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1. gali98
   

   Hello all.
   

       I am a relative newcomer to the hardware tinkering scene. I have had an arduino for a long time, but only recently got it out and started messing with it.
   
   I wanted to do some experiments in wireless, but wasn't a big fan of the price of xbee (Plus I always like a challenge.)
   
   So I stumbled onto this site, and think all the stuff going on here is pretty exciting and interesting. 
   
   So now on to the meat of the post. I purchased a jeeNode kit from Modern Device (915MHz) to see what I could do. (I purchased another radio as well to use with my arduino before discovering that it wasn't as simple as hooking up a few wires... But.. that is another topic for another time.)
   
   So I got in my kit, and soldered it all up. I am not the greatest at soldering yet, so it took me about 1.5 hours. But when I inspected everything, all the joints looked good, and it didn't seem to have any shorts. But nothing worked.
   
   In an experiment to try and get something working, I desoldered the RF radio (which was one of my first mistakes...) Doing this, I managed to mess up most of the gold leads on the PCB as well as the radio. My fault. I guess that's how we learn... So now that you know background, I was wondering if anyone could answer a few questions I have so that I might do better in the future.
   1. First of all, I have no idea why the JeeNode still doesn't work. (Not the wireless part... I can't even get it connected to a serial monitor.)
   
   I know the usb-bub board is working because I'm getting the usb port showing up in the Arduino IDE. I made sure all the components are in the right place, and right orientation. Also as I said, all the solder joints look good. But I try to connect with the serial monitor, but I get nothing. 
   2. What options am I supposed to use in the IDE to program the JeeNode? The wiki says to use "Arduino Duemilanove or Nano w/ ATmega328" but I thought it was a 3.3 volt board? In any case when trying to program it, I get the standard "avrdude: stk500recv(): programmer is not responding" error. (But that is probably related to it not working anyways.)
   3. One thing that really confused me is the usb-bub... The JeeNode is 3.3V right? So why does it take 5V from the usb-bub? And while on the subject of voltages, I found some interesting stuff. Everywhere I measure from a "pwr" to a "gnd" I get 5 volts. But everywhere I measure from "+3v" to "gnd" I get just under 2 Volts. Maybe that can tell you why the board isn't working?
   4. Kind of unrelated, but one question I've had for a while through all this is what exactly should I be using for soldering?
   
   I have a cheap 30W iron with a pointed tip, and resin core solder... Is there something you might recommend as working better for electronics?
   5. Finally, when taking the radio off the JeeNode, I managed to rip some of the golden leads off of the radio... Is there any hope of salvaging it, or is it pretty much dead?
   Thanks so much! As soon as I can get the money (and answers) I'm going to buy another kit and give it a go.
   

   Kory

   Posted 21/02/2010 19:39:14

2. gali98
   

   A quick update... I now realize that the regulator will take 5 volts easily and step it down to 3.3V...
   But that still doesn't explain the 5V and ~2V I mentioned before...
   Kory

   Posted 21/02/2010 19:57:38

3. jcw
   

   The 2 volts is fishy. That will definitely prevent things from working because the ATmega and the radio all run off this internally regulated 3.3V supply.

   Unsoldering the radio is very tricky, as you've found out. My suggestion would be to get a new PCB and bring the components over (i.e. unsoldering the rest of them). Once traces get loose, it's hard to get back on track.

   To "debug" this sort of stuff, you'll need to proceed carefully. Remove the ATmega and radio, and don't put them back until you've figured out why the +3V isn't there (it's actually 3.3V to be precise).

   Note that the JeeNode comes with a pre-loaded sketch. So when it works, you'll see serial output right away when connected to the Arduino IDE with the console window open.

   The 5V from the USB BUB is to feed the MCP1702 regulator on the JeeNode, which then drops it to 3.3V for the rest of the board.

   Soldering iron: I use a simple 15W Weller (40W would be better). Important part is to use a temperature-controlled one with a thermostat, not one of them burn-all-you-can models. Treat the tip well, and it'll keep its coating and will work fine for years (decades even, in my case).

   Posted 21/02/2010 23:17:11