[Solved] Can I use a touch display directly on the arduino pro mini?

Other Hardware Displays
1

Hi,

first of all, sorry if this question is stupid, but I searched the internet up and down, and still don't have an answer (or maybe my search terms were too dumb because I have no clue at all).

I just bought an Arduino Pro Mini 5V 16MHz with a Atmega328P-AU controller. Is it possible to directly connect a (~3") touch display to this device? Everywhere I look, they only mention either Arduino Uno or Mega but never explicitly the Pro mini.

If touch does not work, I could live with that, but having a decent display would be nice. I would need 2-3 free digital IO pins and at least 2 analog pins free after connecting a display.

So, is it possible? Or do I need some other hardware to make that possible? I don't need the SD card slot on the display, I only want to show some data and maybe small graphical elements.

2

Yes it's possible. Promini uses same '328P chip as the Uno. All 20 IO are available.
Only concern is power - promini has little 5V regulator that can only supply 150mA. How much does the display need?

3

Hi,

thanks for the reply. I haven't checked the power draw of the displays yet since I didn't knew if it's even possible.
But the first display I just checked (2.8") needs about 100ma (2.8 TFT Touch Shield for Arduino with Resistive Touch Screen : ID 1651 : $34.95 : Adafruit Industries, Unique & fun DIY electronics and kits) so I think that should be ok. On the other hand, I still could power the display from a dedicated power supply I guess.

4

Hi again,

today I got my Arduino pro mini as well as a cheap 2.8" touch display (seems to be an Adafruit clone). Connecting was easy and the TFT example was working out of the box. The only problem I have is, that the display is extremely dark.

I don't know if it's somehow broken, or if I do need to change anything. As far as I can tell, background light should be on all the time (setting Pin7 to HIGH does not change a thing).

Did I miss something? Or is it just broken? The text for example is nearly not visible, some graphics are ok to see. When the display powers up, it flashes pretty bright for a moment, but then goes dark again.

5

Please post a link to the actual display that you purchased.

Life is much simpler with a Shield. It just plugs into the Uno / Mega / Due ... and we know how your wiring connections are made. The Shield contains any level shifter circuitry.

Yes, you can connect all 21 wires to a Pro Mini. Via 18 level shifter circuits.
If you do everything carefully, it will all work fine.

You can buy a 2.4" red Touch Shield + Uno clone for about $15. It will work first time.

David.

6

Maybe this TFT: SmartGPU 2, 2.4" or 3.5"

Wiring (only 5 wires!!):

SGPU2 Arduino Pro

Reset reset-arduino
TX RXI
RX TXO
3V3 3V3
GND GND

7

Or this: Gameduino 2 (4.3")

Arduino             Gameduino 2

GND pwr                Signal ground
5V  pwr                Main supply: 5-7V
11  in                 SPI MOSI
12  out                SPI MISO
13  in                 SPI SCK
8   in                 GPU SEL
9   in                 SD SEL
2   out                INTERRUPT
A2  out                ACCEL_Z
A1  out                ACCEL_Y
A0  out                ACCEL_X

Maximum wiring length = 15-17 cm

8

Hi,

I bought this one:

http://www.ebay.com/itm/NEW-2-8-Inch-TFT-LCD-Display-Touch-Screen-Module-with-For-Arduino-UNO-BE-/121872156330?hash=item1c602586aa:g:FzUAAOSwpRRWoZaI

Everything was wired according to the comments in the graphic tests example (except for LCD_CD which was not available on the display so I just connected it to LCD_RS..).

Everything works, except for the fact that the display is way too dark.

9

Thanks for posting your Ebay link.

LCD_CD (CommandData) is just another name for LCD_RS (RegisterSelect).
The board has level shifter chips. It works with both 5V logic (Uno) and 3.3V logic (Due).

Your backlight should be of sensible brightness. It uses the AMS1117 regulator (which is supplied by the 5V pin).

I am always sceptical of Pro Mini owners. Have you really connected every pin correctly?
With a Uno or Mega owner, I know that the connections are correct.

Which controller does it actually have?
The MCUFRIEND_kbv library will tell you.

David.

10

Hi,

sorry for the late reply, I had to do some over hours. I tried the MCUFRIEND_kbv library, but unfortunately none of the examples did work. I tripple checked the wiring and everything is in place.

But I found out something: If LCD_RST is connected to an analog pin, the backlight works, but the display just flickers from time to time. There are no graphics or text.

If I connect LCD_RST to the reset pin of the arduino (as written in the Adafruit code comments) backlight does not work, but the text and graphics are displayed :stuck_out_tongue:

Now I only need to get a mix of both :slight_smile:

11

You have a regular Blue 2.8" Uno shield. MCUFRIEND_kbv will identify your controller.
Use the LCD_ID_readreg sketch. Paste from the Terminal. Post it here.

Borrow or buy a Uno if you can't wire your Pro Mini correctly.
All the signals are printed on the Shield. You just need to connect ALL the pins to the Pro Mini.

David.

12

Hi,

here's the output from readreg:

reg(0x0000) 00 00	ID: ILI9320, ILI9325, ILI9335, ...
reg(0x0004) 00 00 00 00	Manufacturer ID
reg(0x0009) 00 00 61 00 00	Status Register
reg(0x0061) 00 00	RDID1 HX8347-G
reg(0x0062) 00 00	RDID2 HX8347-G
reg(0x0063) 00 00	RDID3 HX8347-G
reg(0x0064) 00 00	RDID1 HX8347-A
reg(0x0065) 00 00	RDID2 HX8347-A
reg(0x0066) 00 00	RDID3 HX8347-A
reg(0x0067) 00 00	RDID Himax HX8347-A
reg(0x0070) 00 00	Panel Himax HX8347-A
reg(0x00A1) 00 00 00 00 00	RD_DDB SSD1963
reg(0x00B0) 00 00	RGB Interface Signal Control
reg(0x00B4) 00 02	Inversion Control
reg(0x00B6) 00 0A 82 27 04	Display Control
reg(0x00B7) 00 06	Entry Mode Set
reg(0x00BF) 00 00 00 00 00 00	ILI9481, HX8357-B
reg(0x00C0) 00 21 00 00 00 00	Panel Control
reg(0x00CC) 00 71	Panel Control
reg(0x00D0) 00 00 00	Power Control
reg(0x00D2) 00 00 00 03 03	NVM Read
reg(0x00D3) 00 00 93 41	ILI9341, ILI9488
reg(0x00DA) 00 00	RDID1
reg(0x00DB) 00 00	RDID2
reg(0x00DC) 00 00	RDID3
reg(0x00EF) 00 03 80 02 02 02	ILI9327
reg(0x00F2) 00 02 02 02 02 02 02 02 02 02 02 02	Adjust Control 2
reg(0x00F6) 00 01 00 00	Interface Control

Maybe I have a MCUFriend clone? Because all that's written on my board is:

2.6"/2.8"TFT LCD Shield

Nothing about MCUFriend...

13

You have got a Blue 2.8" Shield with an ILI9341 controller.

The MCUFRIEND_kbv library should detect the ID. And run fine.

Many other libraries should work too. But you may need to tell them that it is an ILI9341.

Yes, you do need to connect all the pins. Especially the LCD_RST pin to Analog#4.

David.

14

I have connected all pins. I even re-wired it for the 5th timer, but the result is still the same: The display works, the graphic demo runs, but the display is way too dark, and the backlight just does not light up.

So, there are only two possible reasons I can think of:

  1. The display is somehow damaged
  2. The display does not like my arduino pro mini 5V -> Is it possible that the display has problems with the 5V output of the pins?

Maybe I should just send it back and try to get a new one.

15

Borrow a friend's Uno. If it is "dark" with a proper Arduino, send the display back.

Otherwise, have you checked the voltages on the 3.3V pin and the 5V pin of your Pro Mini?

David.

16

The Pro Mini 5V does not have 3.3V out. It's available with 3.3V and 8MHZ or 5V and 16MHZ. As far as I understand depending on the version you have, the VCC out either delivers 3.3V or 5V.

The display can be powered with either 3.3V or 5V (two different pins) so I don't think that this is a problem.
Unfortunately I don't know anyone who has an Arduino. Maybe I can check the display on one of my Raspberry PIs

17

Ah-ha. You will need a 3.3V pin and a 5V pin. So your Pro Mini will not work with these shields. (without modification)

The Nano has got a 3.3V pin and a 5V pin. And so do Uno, Zero, Due, Mega, ...

Life is considerably easier with a properly mating Shield.

David.

18

You mean I need to provide both voltages to the display? 5V AND 3.3V? I thought it either one or the other?

19

Yes.

20

Aww...that explains a lot I guess. Well, I have to wait for the 3.3V regulators I ordered I guess. Thank you for your patience. I will update this post as soon as I have tested it with additional 3.3V input.