Tweet-a-watt - Lessons learned and suggestions

XBee projects like the adapter, xBee tutorials, tweetawatt/wattcher, etc. from Adafruit

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ck1
 
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Joined: Sun Jul 12, 2009 6:28 pm

Tweet-a-watt - Lessons learned and suggestions

Post by ck1 »

After purchasing the xbee adapter kit, then the xbee add on a kit, and soldering all together and having it work flawlessly, I figured I'd jump in a few more.

The second time was abit harder.

After I updated the firmware on 7 more xbees and changed the settings, I got everything hooked up on the first tweet-a-watt, the LCD kept on dimming and the xbee reseting with each transmission. I checked the soldering 10+ times, I upped the capacitors to extend the startup / reset delay and even tried doubling up the big cap with no luck. I even swapped out 5 other xbees with the same results. Then, I tried it on 3 other kill-a-watts. Still the same issue. I even soldered up a completely different kit and still the same result.

In a last ditch attempt, I pulled my original tweet-a-watt and compared the components. Exactly the same. Finally, I swapped the xbee from the original to the new kit and it worked!!

So, some more debugging later, I figured it out - I was the bug.

In a fit of lazyiness, I copied and pasted the settings from the instructions all at once (using assemble packet in X-CTU terminal section"
"ATMY=1,SM=4,ST=3,SP=C8,D4=2,D0=2,IT=13,IR=1"
What keyed me off that this was the issue was that the setting IR=1A and that my settings didn't seem to be saving even though typed "atwr".

I realized I never hit enter after IR=1. (because I got "OK\nOK\nOK\nOK\nOK\nOK\nOK\n" (missing one OK)) So IR was being set to 1 + the a from atwr (effectively ...,IR=1atwr (since twr aren't valid hex)). That also explains why the settings seemed to have problems saving.

After fixing this, I plugged it all back together and ... it still didn't work !?!?!? I tracked this down to a bad kill-a-watt.

So, some suggestions

1) test ALL kill-a-watt prior to soldering (just plug them in and make sure everything seems reasonable. w/ nothing plugged in, the amps on the b0rked one read 20!)
2) program your xbee, write, unplug, plug back in and verify each setting
3) do all this before you start soldering!!

This could save you 2 days of pain and suffering, high blood pressure, hair loss, drinking problems, etc..

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