IoT Printer Kit Power Issue?
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IoT Printer Kit Power Issue?

by goatrider on Wed Nov 21, 2012 1:44 pm

I just put together the IoT Printer kit from adafruit - neat little setup! I'm having what I think is a power issue with it though - or maybe my Arduino is acting up or something...

I followed all the instructions to the letter, and loaded the Gutenbird sketch, and it connects to twitter and searches for @myusername and does all its hoopajoops, and when it finds a tweet and goes to print, I get a continuous loop of printing the person's username, the arduino resetting, the program restarting, printing the person's username, the arduino resetting, the program restarting, etc, etc, ad infinitum until i turn it off. The printer will feed to the next line at the beginning of the tweet, but It looks like a power issue to me, like when the printer starts printing, the arduino doesn't have enough power and is just resetting...

When I do a print test (hold the little printer button and turn on the unit's power) it prints its little character map thing like it should, in its entirety, so the printer itself looks just fine.

Is the 5v 2A adapter that comes with the kit really enough power for the Uno + the eth shield + the printer? I don't think it's a faulty power adapter, I had another 5v 2A adapter from another project, and I used that to similar results.

I should also mention that I set up an instance of newsinternational's IoT Assistant software and tried running that as an alternative to Gutenbird to see if it was just some kind of software weirdness (highly unlikely I know), and got the same result...first line of text, then reset.

Anyone have a similar experience or can shed a little light on this for me?
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Re: IoT Printer Kit Power Issue?

by pburgess on Wed Nov 21, 2012 5:09 pm

This latest batch of printers seems to print really dark (i.e. lots of current)...so let's try backing off on the 'heat time' setting. In the Gutenbird sketch, around line 97, modify the 'begin' statement there, adding a heat time value (0-255). The library default is currently 255, so try this to start:

Code: Select all | TOGGLE FULL SIZE
  printer.begin(100);


If that works (but prints too light), you can nudge the value upward to find the right balance of print density and power stability. Or if it still craps out, try working downward.

Let me know what figure you arrive at. This is not the first time it's come up, so it's probably time to make this a permanent change in the library.
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Re: IoT Printer Kit Power Issue?

by goatrider on Wed Nov 21, 2012 6:56 pm

Nice, I'll give it a shot...as soon as I get a new chip for my uno, I think I fried this one :P

The sketch uploads fine but fails verification, I get the dreaded:

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0000
0x0c != 0xff
avrdude: verification error; content mismatch
avrdude: Send: Q [51] [20]
avrdude: Recv: . [14]
avrdude: Recv: . [10]

From what I see here: viewtopic.php?f=25&t=33771

...looks like replacing the chip might help. *sigh* heh

Anyway, not entirely germane to this thread, SO - cant wait to try it out and let you know! Thanks for the insight! :-)
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Re: IoT Printer Kit Power Issue?

by goatrider on Tue Nov 27, 2012 7:23 pm

Alright, well I replaced the entire Uno, re-uploaded the program with your modification, and now the text is significantly lighter, but it's doing the same thing - prints out the tweeter's name, then resets, ad infinitum.

I tried going from 100, down to 80, down to 60, and finally down to 30 (entirely illegible) and it still resets itself :(

I made sure the tweet it's trying to print doesn't have any weird characters that might confuse something either. Very weird.

Any other thoughts?
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Re: IoT Printer Kit Power Issue?

by goatrider on Mon Dec 10, 2012 11:03 am

Bump
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Re: IoT Printer Kit Power Issue?

by DarkStar on Mon Dec 24, 2012 4:58 pm

Well, I'll be receiving my kit right at the start of the new year along with the Arduino Uno and Ethernet Shield so I'll have to see if I have the same issue. Have you tried measuring the DC current?
--Chris ^_^
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