help me choose an lcd

Other Hardware Displays
1

I'm looking for an inexpensive capacitive tft. I recently bought a 3.2"off buy display but I get nothing but white screen and they basically have no service or warranty.

I'd like to stay around 3.2. I'd buy the ada lcd but it's expensive. I'm looking into a project I'll need more than 1 screen for them so trying to keep cost down.

Can anyone suggest a screen with decent refresh? And I can use 4 wire spi? I've been almost 2 weeks trying everything with that other screen but all failed so buy display got the last of my money.

Oh I'm also using an uno and mega.

Thanks in advance

2

First off. Why not say which display from BuyDisplay? What are your problems?
We could probably get you going.

All TFT bare modules are 3.3V. You must provide level-conversion for a 5V Arduino.

I suggest that you buy a display that is already sold as a single shield.

  1. it will have appropriate level-converters
  2. it will be mechanically and electrically stable.
  3. the supplied example code will work out of the box (if it has come from a reputable supplier)

Most of the smaller shields are 8-bit parallel and fit on a UNO. They just have a resistive Touch Panel.
Many are 16-bit parallel and fit on a MEGA (or DUE). They generally have a Touch Controller chip.

Very few are SPI shields. e.g. Waveshare, Seeed, Adafruit, ...
Even fewer have Capacitive Touch.

I suggest that you sit down and think about your requirements.

Of course, you can buy an Adapter shield and mount a 40-pin display (or a bare module)
The Adapter shield looks after the electrical shifts and connections.

David.

3

Thanks David for getting back to me
I really appreciate it. That is the screen I bought. I do have the shield coming that fired between the Arduino and lcd.

I assumed that this would work via 4 wire spi, I've downloaded the datasheet, files and demos. Spent 2 weeks researching and trying different pinouts. The most I can get is it to flicker a few times or just be solid white.

This is my first time experimenting with Arduino and tft do I'm very green so I might need a little push I'm the right direction lol.

I want to do some home automaton in my garage for my battery charges and other equipment, electronics had always been my interests ever since I had my first pong game on the old turn dial tv lol

I'm looking I guess for a reputable source for a well supported tft. I have 3 unos and 1 mega , couple of mks gen 1.4 and s base at my disposal.

Anything u can suggest I'm sure would be fine with me.

Thanks again David

4

Also I should add that I ordered the screen with 40 pin header for 4 wire, 5v psu line
If that helps any.

5

Buydisplay provide documentation on "how to interface" your display i.e. provide 5V to 3.3V level conversion. What do you think their Arduino shield does for you?

If you are prepared to use resistors or converter chips, I am sure we can get you operational.

Unfortunately, Arduino owners tend to "believe" Ebay vendors that say you can run at 5V. At least BuyDisplay provides honest advice.

Note that you can run a Uno from an external 3.3V if you disconnect the USB cable.
A Mega2560 can not run at 3.3V

David.

6

Not much docs really. The interface is what I used. I read about the 3.3v which is why I chose the 5v line in assuming the shield it's attached to would drop the voltage.

I have handfuls of resistors. I'm willing to do what I have to do!

7

I'll be off work in an hour or so. I'll post what pins I was using.

8

Just visited your link. What options did you choose?
There is an interfacing document.
There are demo codes for 8051 and 4-wire SPI.

Look at Bodmer's posts. He shows how to connect a 4-wire SPI ILI9341 display.

Both how to wire resistors and an Arduino Library. So if you wire up correctly, his examples and library should work straight out of the box.

BuyDisplay provide a 5V/3.3V option but all this does is provide the correct VCC to the chips.
You still need to translate the logic to 3.3V

David.

9

david_prentice:
Just visited your link. What options did you choose?
There is an interfacing document.
There are demo codes for 8051 and 4-wire SPI.

Look at Bodmer's posts. He shows how to connect a 4-wire SPI ILI9341 display.

Both how to wire resistors and an Arduino Library. So if you wire up correctly, his examples and library should work straight out of the box.

BuyDisplay provide a 5V/3.3V option but all this does is provide the correct VCC to the chips.
You still need to translate the logic to 3.3V

David.

This is probably the best description I've read!! Thank you thats where I went wrong. I'm not changing the voltage on the logic. See total newbie.

My options were
Interface: pin header 4wire spi.
PSU: 5v
Screen Cap
Font: ER3304-1

I'm going to post some links to pics. IN a few mins. Where do I find those posts? In this sub forum?

Thanks for the help again!

10

Heres a few pics!

[Album] imgur.com
11

If you look at the Arduino Shield page, there are links to Arduino library and examples specifically for the BuyDisplay boards.

No, I don't have your particular ILI9341 display, but I can always test the BuyDisplay code on my own displays. Likewise, Bodmer's, Marek's, Adafruit's, ...

You will be amazed by the speed of these libraries, and the performance of an ILI9341.
Your display should work fine. It will be interesting to hear how you get on with the 3304 Font chip.

You will be equally amazed by how many punters insist on using 5V logic with 3.3V controllers. And how they are too tight to buy series resistors.

David.

12

haha I'll buy what I need. The reason i went cheaper display is because I may do others around the house. If i do I'd like to keep cost to a min.

I found bodmer's Instructable. I see the resistors. Funny thing is I already read that before and I guess with trying to digest mass information over the past week or so I suppose I confused myself.

So what exactly do I use this for
http://www.buydisplay.com/download/democode/ER-TFTM032-3(4-wire-spi)_TP_SD_FONT_FLASH.rar

Like most libraries have examples with with the ino files. I assume this is what I would point to in a custom sketch? Or am I way off?

13

Also YEs I have those files on the Shield adapter page. Only thing not included was Wire. I downloaded that and flashed with no errors. But I was only getting the white screen(no resistors).

I Ordered that Shield. I said what the heck. Its half way to me now from buydisplay.

14

BuyDisplay publish the schematic of their Shields.
They do not publish the schematic of the display board.

It is quite possible that among all those SMD resistors in your photo, they already have 1k0 series resistors on the SPI lines.
Only you can investigate your pcb with a DMM.

I would start by following Bodmer's wiring in his Instructable.
Try the Arduino Library examples.

Investigating your 3304 Font chip will be left to another day.

David.

Edit. Just looked at the "Arduino Library examples for ILI9341" from BuyDisplay.
They are very trivial. And use UTFT which is very SLOW. Bodmer's library would be better.

15

Thats interesting. Ok I found the right howto!! I'll post back tomorrow. I should give it a go after lunch!

Again I appreciate pointing me in the right direction!!

16

Alright I have it working. The mistake was pin 25 on the LCD. Here is how we wired it.

LCD:
Buydisplay|-------|Resister|-------|UNO

LCD_/CS 23------1.2kΩ------->10
D/C(SCL) 24------1.2kΩ------->13
WR(D/C) 25------1.2kΩ------->9
LCD_SDI 27------1.2kΩ------->11

Thanks again!!

Now we have to try to get the Cap touch working. Do we have to add resistors to those?

We tried a few ways to wire but the touch isn't working as of yet. We are using the adafruit/bodmer's post.

17

Are both the pins on the lcd and arduino supposed to have voltage? 5v?

18

If you asked BuyDisplay to configure your display for 5V supply, they would have selected JP=OPEN

Look at Table 4.2 on page 13 of your PDF.

Yes, you connect 5V from your Arduino power pins. But you ensure 3.3V logic goes to the control pins. (e.g. via your series resistors)

If you want to go 3.3V only, you change the JP setting, you don't need series resistors, you can't use USB with Uno, Nano, Mega, ... IF YOU CONNECT TO USB YOU WILL BLOW UP YOUR DISPLAY.

The 3.3V pin on a Uno is very wimpy. The tiny 3.3V regulator can not supply backlight current.

In practice: Leave JP as it is. Use your series resistors. Use your Nano/Uno from USB (5V).

David.

19

Yes David I did select 5v. I did some searching before I bought this. So I had an idea what to order.

JP is unsoldered!

We have the LCD demo's working!! But cannot get the touch to work. Using pins A4 & A5. Even tried resistors.

Do you know of any posts or guides to get the info from? We spent from 3pm till 10pm messing with it and nothing.

Any help is appreciated.

20

I would concentrate on the regular Graphics first. i.e. run through all of Bodmer's examples, try Adafruit_ILI9341 and its examples, likewise Marek's ILI9341_due library.

Yes, there are slight differences in the method() APIs.
But at least they are more intuitive than the UTFT library methods.

See what suits you best.

I do not have a Capacitive Touch. Adafruit does. Try the Adafruit library examples.

I presume that your Touch has a TOUCH_CS pin and a TOUCH_IRQ pin. These need the series resistors.
The MOSI, MISO, SCK pins just go to the regular SPI bus. Either with their own series resistors or directly to the TFT SPI pins (i.e. already protected from 5V Arduino).

I would guess that the Capacitive has a different initialisation to a Resistive Touch.
But the methods that your program calls would have the same API.

Get some familiarity with the TFT first. I am sure that there are members with Capacitive on this Forum. Just wait for a day or three.

David.