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4-digit 7-segment led stopped working
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4-digit 7-segment led stopped working

by kenvdh on Fri Nov 20, 2020 3:55 am

Hello,

Love the simplicity of using adafruit products in my small projects with the kids.

I have an adafruit 4-digit 7-segment led with ht16k33 backpack that has worked for a few weeks.
But a few days ago it stopped working. Is has been in a kids growth meter project: a trinket pro, with ultrasonic distance sensor as input, and the led as output.

I removed the led from the project and hooked it up to my arduino uno for testing. Used different cables to rule out cable issues.
The leds no longer light up. The chip on the backpack gets warm.

Test code is the example code from adafruit "sevenseg":

Code: Select all | TOGGLE FULL SIZE
/***************************************************
  This is a library for our I2C LED Backpacks

  Designed specifically to work with the Adafruit LED 7-Segment backpacks
  ----> http://www.adafruit.com/products/881
  ----> http://www.adafruit.com/products/880
  ----> http://www.adafruit.com/products/879
  ----> http://www.adafruit.com/products/878

  These displays use I2C to communicate, 2 pins are required to
  interface. There are multiple selectable I2C addresses. For backpacks
  with 2 Address Select pins: 0x70, 0x71, 0x72 or 0x73. For backpacks
  with 3 Address Select pins: 0x70 thru 0x77

  Adafruit invests time and resources providing this open source code,
  please support Adafruit and open-source hardware by purchasing
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries. 
  BSD license, all text above must be included in any redistribution
 ****************************************************/

#include <Wire.h> // Enable this line if using Arduino Uno, Mega, etc.
#include <Adafruit_GFX.h>
#include "Adafruit_LEDBackpack.h"

Adafruit_7segment matrix = Adafruit_7segment();

void setup() {
#ifndef __AVR_ATtiny85__
  Serial.begin(9600);
  Serial.println("7 Segment Backpack Test");
#endif
  matrix.begin(0x70);
}

void loop() {
  // try to print a number thats too long
  matrix.print(10000, DEC);
  matrix.writeDisplay();
  delay(500);

  // print a hex number
  matrix.print(0xBEEF, HEX);
  matrix.writeDisplay();
  delay(500);

  // print a floating point
  matrix.print(12.34);
  matrix.writeDisplay();
  delay(500);
 
  // print with print/println
  for (uint16_t counter = 0; counter < 9999; counter++) {
    matrix.println(counter);
    matrix.writeDisplay();
    delay(10);
  }

  // method #2 - draw each digit
  uint16_t blinkcounter = 0;
  boolean drawDots = false;
  for (uint16_t counter = 0; counter < 9999; counter ++) {
    matrix.writeDigitNum(0, (counter / 1000), drawDots);
    matrix.writeDigitNum(1, (counter / 100) % 10, drawDots);
    matrix.drawColon(drawDots);
    matrix.writeDigitNum(3, (counter / 10) % 10, drawDots);
    matrix.writeDigitNum(4, counter % 10, drawDots);
   
    blinkcounter+=50;
    if (blinkcounter < 500) {
      drawDots = false;
    } else if (blinkcounter < 1000) {
      drawDots = true;
    } else {
      blinkcounter = 0;
    }
    matrix.writeDisplay();
    delay(10);
  }
}


Wired to the uno as follows:
backpack C --> uno A5
backpack D --> uno A4
backpack - --> uno gnd
backpack + --> uno 5v


Anything else I can test ?
Or is the led / backpack broken ?


Thanks,
Ken.

kenvdh
 
Posts: 15
Joined: Wed Oct 28, 2020 9:51 am

Re: 4-digit 7-segment led stopped working

by kenvdh on Fri Nov 20, 2020 6:25 am

I figured a photo could be helpful.
Attached.

Regards,
Ken.
Attachments
20201120_111739-s.jpg
20201120_111739-s.jpg (760.38 KiB) Viewed 109 times

kenvdh
 
Posts: 15
Joined: Wed Oct 28, 2020 9:51 am

Re: 4-digit 7-segment led stopped working

by adafruit_support_carter on Fri Nov 20, 2020 2:37 pm

That wiring looks generally correct.

Can you post a photo of the backside of the matrix also. Maybe something obvious there?

adafruit_support_carter
 
Posts: 17777
Joined: Tue Nov 29, 2016 2:45 pm

Re: 4-digit 7-segment led stopped working

by kenvdh on Fri Nov 20, 2020 4:46 pm

Hello,

Sure, a picture of the backside attached.

Kind regards,
Ken.
Attachments
20201120_214135-s.jpg
20201120_214135-s.jpg (931.35 KiB) Viewed 108 times

kenvdh
 
Posts: 15
Joined: Wed Oct 28, 2020 9:51 am

Re: 4-digit 7-segment led stopped working

by adafruit_support_carter on Fri Nov 20, 2020 4:51 pm

Thanks. Can't quite tell because of the focus. Nothing super obvious. Does it look like any of the pins are shorted? By a solder bridge or even some debris?

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Posts: 17777
Joined: Tue Nov 29, 2016 2:45 pm

Re: 4-digit 7-segment led stopped working

by kenvdh on Fri Nov 20, 2020 5:12 pm

Hi,

Sorry its small and shiny ... focus on the soldering is not working with my phone.

I don't see any shorted pins.
Besides it did work for some time. If I shorted something with soldering, would thet not have been noticed right away ?

Maybe between the backpack and led something got stuck. I will check tomorrow in daylight.
Thanks

kenvdh
 
Posts: 15
Joined: Wed Oct 28, 2020 9:51 am

Re: 4-digit 7-segment led stopped working

by adafruit_support_carter on Fri Nov 20, 2020 6:06 pm

It sounds like this was in some other setup? With a distance sensor, etc. What did that setup look like?

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Posts: 17777
Joined: Tue Nov 29, 2016 2:45 pm

Re: 4-digit 7-segment led stopped working

by kenvdh on Sat Nov 21, 2020 5:01 am

Hello,

Thanks for your reply.
I tried to make a photo of the space between the led and the backpack. Seems fine, can't see anything in between.
The old setup no longer available, we mostly build stuff into lego, and had to disassemble to get the part out.


Regards,
Ken.
Attachments
20201121_094720-s.jpg
20201121_094720-s.jpg (872.5 KiB) Viewed 96 times
20201121_094727-s.jpg
20201121_094727-s.jpg (650.48 KiB) Viewed 96 times

kenvdh
 
Posts: 15
Joined: Wed Oct 28, 2020 9:51 am

Re: 4-digit 7-segment led stopped working

by kenvdh on Sun Nov 22, 2020 8:36 am

Hi,

Anything else I can test ?
The demo "sevenseg" does not seem to make the leds light up.


Thanks,
Ken.

kenvdh
 
Posts: 15
Joined: Wed Oct 28, 2020 9:51 am

Re: 4-digit 7-segment led stopped working

by adafruit_support_carter on Mon Nov 23, 2020 2:03 pm

Thanks. There's nothing super obvious as to what has happened. The fact that it is no longer working and getting warm seems to indicate something has happened though. Being used for several weeks in a lego enclosure - just one of those things that can happen.

I'd suggest snipping off the long leads from the LED module (not the header pins) after soldering. That would reduce the amount of conductive / pin connected leads are exposed to potential shorting.
https://learn.adafruit.com/adafruit-led ... ep-3052417

adafruit_support_carter
 
Posts: 17777
Joined: Tue Nov 29, 2016 2:45 pm

Re: 4-digit 7-segment led stopped working

by kenvdh on Thu Nov 26, 2020 4:53 am

Hello again,

Thanks for your reply.
I'll cut off the long parts, and check the soldering again.
Will keep this post up to date as soon as I know more.

Kind regards,
Ken.

kenvdh
 
Posts: 15
Joined: Wed Oct 28, 2020 9:51 am

Re: 4-digit 7-segment led stopped working

by kenvdh on Thu Dec 03, 2020 3:59 am

Hello,

Found some time to clip off the long parts and test again.
Same result. Nothing lights up.

Added some photos of the clipped board.


Please advise ?
Attachments
20201203_085404.jpg
20201203_085404.jpg (502.81 KiB) Viewed 23 times
20201203_085309.jpg
20201203_085309.jpg (531.57 KiB) Viewed 23 times

kenvdh
 
Posts: 15
Joined: Wed Oct 28, 2020 9:51 am

Re: 4-digit 7-segment led stopped working

by adafruit_support_carter on Thu Dec 03, 2020 1:45 pm

There's a chance it may just be dead. Something may have happened to it while living in the lego enclosure.

One last thing you could try is seeing if the backpack can be seen with an I2C scanner sketch. Try running this with the backpack connected:
https://playground.arduino.cc/Main/I2cScanner/
and see if it reports back finding the address.

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Posts: 17777
Joined: Tue Nov 29, 2016 2:45 pm

Please be positive and constructive with your questions and comments.