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Adafruit 2,2" TFT w/ILI9340C faulfty
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Adafruit 2,2" TFT w/ILI9340C faulfty

by tecmate on Wed Jul 26, 2017 10:55 am

Hi,
I own several of those TFT panels, which I use with Arduino. But meanwhile the 2nd tft turned pale after some weeks constantly being active.

Proper working device looks like:
IMG_20170726_tft_proper.png
IMG_20170726_tft_proper.png (658.98 KiB) Viewed 192 times


and my faulty ones:
IMG_20170726_tft_faulty.png
IMG_20170726_tft_faulty.png (596.39 KiB) Viewed 192 times


What went wrong? How to fix this?

tecmate
 
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Re: Adafruit 2,2" TFT w/ILI9340C faulfty

by adafruit_support_carter on Tue Nov 14, 2017 12:26 pm

But meanwhile the 2nd tft turned pale after some weeks constantly being active.
What went wrong? How to fix this?


It was working and then it wasn't - can you correlate this to anything? Can you post another photo showing how the display is connected to the Arduino.

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Re: Adafruit 2,2" TFT w/ILI9340C faulfty

by tecmate on Tue Nov 21, 2017 5:39 am

adafruit_support_carter wrote:It was working and then it wasn't - can you correlate this to anything?

Correct, it just happend, no correlation.
Everything is mounted in a fixed case, so no shorts can occur.
Probably that came up because the panel constantly got 5V. Meanwhile I moved the VIN from the ICSP 5V pin to pin 11 and added a power on/off screensaver function to my code.
Here is how I wired the TFT:
tft-wired.jpg
tft-wired.jpg (64.64 KiB) Viewed 89 times

GND - ICSP GND
VIN - ICSP 5V (now is Pin 11)
D/C - pin 9
RESET - pin 8
SD CS - /
LCD CS - pin 10
MOSI - ICSP MOSI
MISO - /
SCK - ICSP SCLK
BACKLIGHT - /

tecmate
 
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Re: Adafruit 2,2" TFT w/ILI9340C faulfty

by adafruit_support_carter on Tue Nov 21, 2017 1:05 pm

VIN - ICSP 5V (now is Pin 11)

Try moving this back to a 5V pin. The digital I/O pins can only source a small amount of current, not enough to power the display.

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Re: Adafruit 2,2" TFT w/ILI9340C faulfty

by tecmate on Wed Nov 22, 2017 5:41 am

Well, if I move it back to the 5V pin, it's constantly powered again (what seems to cause that fault) and I can't interrupt the TFT power.
I have 3,3V on my digital I/O pin and the documentation of the TFT says it's ok.

What benefits shall I expect? How does that help to prevent my other screens from turning pale too?

tecmate
 
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Re: Adafruit 2,2" TFT w/ILI9340C faulfty

by adafruit_support_carter on Wed Nov 22, 2017 12:23 pm

Well, if I move it back to the 5V pin, it's constantly powered again (what seems to cause that fault) and I can't interrupt the TFT power.

True. If you want to completely cut power to the display, you'll need to use something like a transistor to do the power switching and then control that via the GPIO. Alternatively, you can leave the display constantly powered and then control the backlight via the BACKLIGHT pin.
I have 3,3V on my digital I/O pin and the documentation of the TFT says it's ok.

Not sure what you mean here. Looks like you are using a Leonardo which is a 5V board. How are you seeing 3.3V on the digital lines?
What benefits shall I expect? How does that help to prevent my other screens from turning pale too?

If you under power the display, by trying to power it from a digital output, it won't work properly.

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Re: Adafruit 2,2" TFT w/ILI9340C faulfty

by tecmate on Wed Nov 22, 2017 12:44 pm

Indeed I'm using a Leonardo Ethernet and I measured 3.3V with a voltmeter on the digital pin I use.

However, I changed the pin AFTER that fault occured. The fault occured while using 5V, so i don't understand how that shall solve the problem?!?

Please find the powering information in that screenshot of your manual.
manual.jpg
manual.jpg (75.63 KiB) Viewed 54 times

Or is that information out of date?


My aim is to fix those 2 screens and prevent the others to become faulty. I'm asking you for your help here.
If they cannot be repaired anyways, please initiate a replacement process in the meantime.

tecmate
 
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Re: Adafruit 2,2" TFT w/ILI9340C faulfty

by adafruit_support_carter on Wed Nov 22, 2017 1:20 pm

You can use the screen with either 3.3V or 5V boards. However, whatever is supplying the power (connected to VIN) must be able to provide adequate current for the display. A digital pin, like PIN 11, will not be able to do that.

You have a second display that is working. How is your second display hooked up? Is it in another setup that is identical to this one?

Indeed I'm using a Leonardo Ethernet and I measured 3.3V with a voltmeter on the digital pin I use.

That doesn't sound good. You should measure 5V if you configure the pin for output and set it high.

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Re: Adafruit 2,2" TFT w/ILI9340C faulfty

by tecmate on Wed Nov 22, 2017 1:38 pm

Now, after disconnecting the panel from the arduino, I can measure 4.8V at pin 11, but will think about a transistor switch.

I have 6 screens and use them all the same way. After the second screen became faulty, I decided to change the pin.
The other 4 are still doing well.

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Re: Adafruit 2,2" TFT w/ILI9340C faulfty

by adafruit_support_carter on Wed Nov 22, 2017 2:02 pm

The other 4 are still doing well.

Cool. So you know that connection scheme works. I assume this is what you specified before:
GND - ICSP GND
VIN - ICSP 5V
D/C - pin 9
RESET - pin 8
SD CS - /
LCD CS - pin 10
MOSI - ICSP MOSI
MISO - /
SCK - ICSP SCLK
BACKLIGHT - /


Now, after disconnecting the panel from the arduino, I can measure 4.8V at pin 11, but will think about a transistor switch.

If you were measuring this when it was connected to VIN of the display, then the lower voltage is probably a result of the fact that you are overpowering the pin trying to use it to power the display.

Try inspecting your soldering on the problematic displays and go over your wiring in general. It's possible there's a marginal connection somewhere creating a signal issue.

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Please be positive and constructive with your questions and comments.