Hi all,
I've been chaining (3) 4 digit 7 segment displays together over I2C using the handy dandy https://learn.adafruit.com/adafruit-led ... t-backpack. My naive understanding is that at 3.3 volts, this should be pretty simple to chain 3 of these guys together. I had been doing this successfully until randomly all of the lights go dead! No clue what happened, wiring job was a pretty clean one too.
Any idea on how to test to see if these are borked? Or is there anything wrong with my assumptions as far as wiring these together safely? For what it's worth I ran a great I2C scanner on my board and it was able to still identify the the 3 devices, despite there not being any light.
Any thoughts would be super appreciated!
Spencer
How to test if 7 Segment Buildpack is Borked.
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Please be positive and constructive with your questions and comments.
- adafruit_support_bill
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Re: How to test if 7 Segment Buildpack is Borked.
It is a good sign that they are responding to the scanner. How are you powering these? Does the 3.3v voltage drop when you try to run the displays?
- sperrys
- Posts: 3
- Joined: Tue Nov 28, 2017 4:13 am
Re: How to test if 7 Segment Buildpack is Borked.
I've just been powering them via a 3.3 volt pin on the board I'm using. Board is powered over micro-usb to usb via usb2 port on my mac. I haven't measured voltage across it though, I can try that. Maybe it's a board issue. Would moving hot to vin pin have any difference?
Thanks for the help, I appreciate it.
Thanks for the help, I appreciate it.
- adafruit_support_bill
- Posts: 88151
- Joined: Sat Feb 07, 2009 10:11 am
Re: How to test if 7 Segment Buildpack is Borked.
Not sure what board you are using. But the 3.3v pin on most Arduino compatibles is not capable of sourcing very much current. 3 displays may just be too much for it.
- sperrys
- Posts: 3
- Joined: Tue Nov 28, 2017 4:13 am
Re: How to test if 7 Segment Buildpack is Borked.
Makes sense. I'll check out the specs on the board, it's esp8266 based. Any ideas for what to do if that's the case? Power externally?
Thanks again for the help.
Thanks again for the help.
- adafruit_support_bill
- Posts: 88151
- Joined: Sat Feb 07, 2009 10:11 am
Re: How to test if 7 Segment Buildpack is Borked.
You may need to find an external 3.3v power supply. They are not as common as 5v supplies, but you can always use a 'buck' regulator to get 3.3v from a 5v source:
https://www.adafruit.com/product/2745
https://www.adafruit.com/product/1066
https://www.adafruit.com/product/2745
https://www.adafruit.com/product/1066
Please be positive and constructive with your questions and comments.