ht16k33 0.54" Alphanumeric grows dim from left to right

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wrayt
 
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ht16k33 0.54" Alphanumeric grows dim from left to right

Post by wrayt »

I have an IMP project with the adafruit ht16k33 / 0.54" Alphanumeric display combo. The display works but the left most digit is bright and each one to the right grows progressively dimmer. I'm using the Squirrel Class to control Adafruit HT16K33-based 0.54in, 4-digit, 14-segment LED via I2C code from github. Any idea what might cause this?

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adafruit_support_mike
 
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Re: ht16k33 0.54" Alphanumeric grows dim from left to right

Post by adafruit_support_mike »

Not a clue..

Does the display/backpack combo do the same thing when you connect it to an Arduino and use our standard test code?

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wrayt
 
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Re: ht16k33 0.54" Alphanumeric grows dim from left to right

Post by wrayt »

Unfortunately I don't have any Arduino stuff to test it with. From further reading I gather changing the brightness should affect all digits as there is only a common set. I can very the brightness but it seems to only affect the first digit on the left of the four. Each one to the right gets progressively more dim with the last one almost unreadable.
...Wray

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zener
 
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Re: ht16k33 0.54" Alphanumeric grows dim from left to right

Post by zener »

Is your 5V solid the whole time? Did you inspect all your solder joints under magnification?

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wrayt
 
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Re: ht16k33 0.54" Alphanumeric grows dim from left to right

Post by wrayt »

Sorry I've been away for a week. I've checked all the joints and they look good. The IMP runs on 3.3V though, not 5V. Would this cause the dimming of the display from left to right? I could apply 5V to the display power pin but I'm not sure if this would feed back to the IMP and perhaps damage it? It kinda looks like there is a drop in voltage from digit to digit. Are there pins I can probe from digit to digit to see what the driving voltage on each digit is? Do you know how the driving voltage is supplied to each digit. I would have thought it should be in parallel but it looks like they are in series somehow.
...Wray

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adafruit_support_mike
 
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Re: ht16k33 0.54" Alphanumeric grows dim from left to right

Post by adafruit_support_mike »

The LCD only uses a single backlight, so any fading from one edge to the other is unexpected.

Could you post a photo of the LCD showing the problem please?

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zener
 
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Re: ht16k33 0.54" Alphanumeric grows dim from left to right

Post by zener »

Isn't it LED? A link to the product in question would help.

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wrayt
 
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Re: ht16k33 0.54" Alphanumeric grows dim from left to right

Post by wrayt »

It is an LED display as mentioned "adafruit ht16k33 / 0.54" Alphanumeric display combo". Unfortunately I can't find any diagrams or data for the HT16K33 board so I'm not sure how it drives the displays and it's an I2C controller so no real idea how it passed the info to the digits.

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zener
 
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Re: ht16k33 0.54" Alphanumeric grows dim from left to right

Post by zener »

I think it needs 5V

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wrayt
 
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Re: ht16k33 0.54" Alphanumeric grows dim from left to right

Post by wrayt »

Sorry guys my fault. I didn't realize I needed both pins marked plus on the ht16k33 tied to the 3.3V. Once I did that the display came up to full brightness. The project i was following didn't make a point of that and it wasn't until I read through an Adafruit project I realized my mistake. Thanks for all your come backs. ...Wray

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adafruit_support_mike
 
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Re: ht16k33 0.54" Alphanumeric grows dim from left to right

Post by adafruit_support_mike »

Glad to hear it's working for you.

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