OLED Screen question

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smoscar01
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OLED Screen question

Post by smoscar01 » Sat Jun 30, 2018 1:33 pm

Hey guys,

I just received a 1.44 inch TFT LCD and I have successfully connected it to the Pi using modprobe to send the framebuffer to the OLED screen.

I am ready now to desolder it from the PCB but I noticed it has a resistor connected to the LED pin (possibly to prevent burning the LED out), a voltage regulator and a capacitor connected to the VCC pin.

Is it safe to desolder the OLED and not add these components when building the VMU?

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Re: OLED Screen question

Post by Trekintosh » Sat Jul 07, 2018 10:53 pm

That’s not an OLED screen, just a normal crappy lcd.

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smoscar01
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Re: OLED Screen question

Post by smoscar01 » Mon Jul 09, 2018 10:09 am

Trekintosh wrote:
Sat Jul 07, 2018 10:53 pm
That’s not an OLED screen, just a normal crappy lcd.
Oh my bad, to be honest I don't really know the difference between both.

Any ideas on the resistor, voltage regulator and capacitor question?

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Re: OLED Screen question

Post by TheKayneGame » Sat Jul 14, 2018 5:01 pm

Hi!

I reccomend Just letting the whole thing be.
the Voltage regulator and resistor are there to regulate the voltage and limit the current.
The LED resistor does not have to be there IF you provide the correct voltage to it (this can be found if there is a datasheet).
The Power regulator is also not needed IF you provide the correct voltage to it (this can also be found in the datasheet).

As for the capacitor it's used for smoothing out the voltage, its not necessary but recommended when working with audio signals.

You can also just trim the PCB with a hacksaw (Thats what i do if components are too large).

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smoscar01
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Re: OLED Screen question

Post by smoscar01 » Tue Jul 17, 2018 4:57 pm

Thanks TheKayneGame!

I don't know if there's a data sheet for the one I bought, I ended up desoldering the screen and components from the PCB. The multimeter then helped me getting their resistance and capacitance.

It seems like the screen works fine with a 3.3 volts input. Without the resistance the colors look a little bit blueish, I am going to try to solder it directly to the wire though.

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Re: OLED Screen question

Post by Kenshin16 » Mon Aug 06, 2018 7:16 pm

smoscar01 wrote:
Tue Jul 17, 2018 4:57 pm
Thanks TheKayneGame!

I don't know if there's a data sheet for the one I bought, I ended up desoldering the screen and components from the PCB. The multimeter then helped me getting their resistance and capacitance.

It seems like the screen works fine with a 3.3 volts input. Without the resistance the colors look a little bit blueish, I am going to try to solder it directly to the wire though.
how did you wire yours? i bought the same exact screen and cant get it to work at all. not even the backlight.

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Re: OLED Screen question

Post by moosepr » Tue Aug 07, 2018 3:21 am

If you backlight looks a little blue, then you're probably over voltage on the little led. Try a 10ohm resistor for the backlight, they only need 3.2v normally, so 3.3 direct does work, but can melt them!
Get a small cheep LCD in your project https://www.sudomod.com/forum/viewtopic.php?f=22&t=2312
Wrap it all round a battery https://www.sudomod.com/forum/viewtopic.php?f=13&t=2292
Or use a custom PCB to make it really small https://www.sudomod.com/forum/viewtopic.php?f=13&t=2512
or make it really really really really tiny!! https://www.sudomod.com/forum/viewtopic.php?f=13&t=2919

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Re: OLED Screen question

Post by smoscar01 » Wed Aug 15, 2018 11:06 am

Kenshin16 wrote:
Mon Aug 06, 2018 7:16 pm
smoscar01 wrote:
Tue Jul 17, 2018 4:57 pm
Thanks TheKayneGame!

I don't know if there's a data sheet for the one I bought, I ended up desoldering the screen and components from the PCB. The multimeter then helped me getting their resistance and capacitance.

It seems like the screen works fine with a 3.3 volts input. Without the resistance the colors look a little bit blueish, I am going to try to solder it directly to the wire though.
how did you wire yours? i bought the same exact screen and cant get it to work at all. not even the backlight.
Hey Kenshin16,

Before I desoldered it from the PCB I tested wiring it to a Raspberry PI 3b using a breadboard (you'd be surprised with the amount of defective screens you can get from China)

Here's how I wired it:

LED -> pin 1
SCK -> pin 23
SDA -> pin 19
A0 -> pin 16
RESET -> pin 18
CS -> pin 22
GND -> pin 9
VCC -> pin 17

As far as I can tell, these screens do not wait for the driver to receive images to turn the led on, so as long as you have the LED, VCC and GND connected properly, you should see the screen's backlight turning on when turning the Pi on. If not, it is possible you might have a defective screen.

This is the only photo I took when I did it, hope it helps:

Image

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Re: OLED Screen question

Post by smoscar01 » Sat Dec 15, 2018 9:52 pm

moosepr wrote:
Tue Aug 07, 2018 3:21 am
If you backlight looks a little blue, then you're probably over voltage on the little led. Try a 10ohm resistor for the backlight, they only need 3.2v normally, so 3.3 direct does work, but can melt them!
Thanks for the advise moosepr

I ended up soldering back the resistor to avoid burning the LED.
Ugly workaroundShow
Image

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