What should I do when use Arduino to control TFT lcd

Thread Starter

LAOADAM

Joined Nov 21, 2018
658
Hi,
I used Arduino UNO controlled two TFT lcds, one just not turned on (no brightness); another one just light on(with quite high brightness white), but not show what I expected, can it be burned?
What should I do to wire them?
Thanks
Adam
 

KeithWalker

Joined Jul 10, 2017
2,045
You can damage TFT LCD displays quite easily by connecting them up incorrectly. I recommend that you find a tutorial on line that will instruct you on how to connect the displays and program an arduino to drive them.There are many different sizes of displays that use a number of different driver chips, so make sure the tutorial is for the type that you have. An example of wording for an online search is "arduino, 1.8" TFT LCD display tutorial" but use the description of your displays.
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
658
You can damage TFT LCD displays quite easily by connecting them up incorrectly. I recommend that you find a tutorial on line that will instruct you on how to connect the displays and program an arduino to drive them.There are many different sizes of displays that use a number of different driver chips, so make sure the tutorial is for the type that you have. An example of wording for an online search is "arduino, 1.8" TFT LCD display tutorial" but use the description of your displays.
Thank you.
That's what I like to know.
I'll do that way.
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
658
hi,
If your UNO is running at 5V, you need a level shifter down to 3.3V for the TFT control I/O pins.

Do have a level shifter module.?
E
Thanks.
I am using 3.3v from Arduino, no level shifter module for the pins yet, can make up by adding resistance?
 

ericgibbs

Joined Jan 29, 2010
14,189
I am using 3.3v from Arduino, no level shifter module for the pins yet, can make up by adding resistance?
hi,
I guess you mean you are powering the Arduino with 5V and the TFT from the Arduino's 3.3V output pin.?

Yes, Use 2K and 3k3, in series, that is 5V* (3k3/5k3) = 3.11V Signal lines...

So 5V Output pins from UNO to the top end of the 2k , the junction of the 2k and 3k3 to the TFT control pins and the bottom end of the 3k3 to 0V.
Do you follow that OK.?
E

E
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
658
hi,
I guess you mean you are powering the Arduino with 5V and the TFT from the Arduino's 3.3V output pin.?

Yes, Use 2K and 3k3, in series, that is 5V* (3k3/5k3) = 3.11V Signal lines...

So 5V Output pins from UNO to the top end of the 2k , the junction of the 2k and 3k3 to the TFT control pins and the bottom end of the 3k3 to 0V.
Do you follow that OK.?
E

E
Thanks.
OK, I'll do it.
 

SamR

Joined Mar 19, 2019
3,615
All of my Unos have both 3.3V and 5V power supply pins. But you do not want to feed something supplied by the 5V pin into a 3.3V device. As to the I/O itself, the AVR chip apparently is both 5V and 3.3V I/O compliant.
 

SamR

Joined Mar 19, 2019
3,615
Where you can get into trouble is with analog signal scaling as it is based on a 5V signal but can be rescaled for a 3.3V signal through the software. The AVR Vcc is rated for 1.6V - 5.5V.

EDIT: For using a lower reference voltage (3.3V) connect the 3.3V supply to the AREF pin to the 3.3V supply pin and use the AnalogReference (EXTERNAL) function in the software. However, this makes all analog inputs scale to 3.3V. Which is fine as long as you don't mix supply voltages to the I/O for analog imputs. Without doing so you would need to adjust the analog input scaling for each 3.3V analog input used as the default is for 5V analog inputs.

There are 3.3V Arduinos, the Due, Fio, and PRO. All others apparently have dual voltage output power supplies.

Also the default voltage for a digital high is 3V so any degradation of the 3.3V supply through devices to the digital input many cause errors.
 
Last edited:

Thread Starter

LAOADAM

Joined Nov 21, 2018
658
Where you can get into trouble is with analog signal scaling as it is based on a 5V signal but can be rescaled for a 3.3V signal through the software. The AVR Vcc is rated for 1.6V - 5.5V.
Thanks.
I found that the 'Arduino Pro Mini' with 8Mhz can operate at 3.3V, just don't know what can be the measurement of pin output high and low?
 

SamR

Joined Mar 19, 2019
3,615
For a 3.3V only Arduino the digital output will be 3.3V Hi and 0V Lo. I have quite a few reference books and they are a bit short on 3.3V information on the mixed voltage cards other than what I posted and even less on 3.3V only cards. My TFT screens that I experimented with were 5V.
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
658
For a 3.3V only Arduino the digital output will be 3.3V Hi and 0V Lo. I have quite a few reference books and they are a bit short on 3.3V information on the mixed voltage cards other than what I posted and even less on 3.3V only cards. My TFT screens that I experimented with were 5V.
Thanks.
I did test two TFTs, wirh 3.3v power, 5v pins from UNO. one never light up, another one light up quite bright, but doesn't show views.
That's why I think one is bad when come, another one probably burnt?
 
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