3.5" lcd - Getting Loster and loster

I have been weeks now trying to do what seems like it should be straightforward. I want to display fairly large numbers on a 3.5" LCD display.

So i bought a 3.5" display. Turns out it has an ili9486 driver chip, and won’t work with an Adafruit library. I have to use MCU Friendly. But that does not allow for large text. According to what I read in this forum, I must use an ili9481 chip.

My new 3.5" display came in, but it has several options as to chips (9486,9481,9341,9488). But it only seems to work if I use that stupid mcufriend library. This leads me to deduce that it is set to 9486. I ran the reg read .ino, and that serial output image is attached.

from what I can see, if I want ili9481, i must use 0x00BF register, but I don’t even know what that means or how to do it.

I think if i can get the display to work with the Adafruit library I can use the adafruit font modifier to get what i want as far as text size goes. Can someone tell me, in pretty simple terms, what i have to say in the sketch to select ili9481 ?

2020-01-07 21 51.png

Posting a link to the display you bought would be an excellent idea.

You have chosen to buy a display with a Raydium RM68140 controller.

Only the stupid MCUFRIEND_kbv library supports this controller.
And since you appear to have a readable display, I suspect that it is a regular Uno Shield.
Of course you could eliminate the "guesswork" by simply posting a link to the item that you have actually bought.

The "Font_simple.ino" example will show you Free Fonts in different sizes.
You can use this online converter to create new Free Fonts.

Your other thread implied that you want letters to be 20mm high on a 3.5 inch diagonal screen. i.e. 133 pixel high.
This is very BIG. You will only get 4 or 5 letters across a 480x320 screen.
Do you really want a full alphanumeric font?
Or do you just need a numeric font e.g. 0-9 ?

There are limitations to the implementation of Adafruit Free Fonts. Letter heights and offsets are limited to 127 pixels.

There are limitations for the AVR C++ compiler when it comes to arrays e.g. the Font data tables.
In practice, this means that alphabetic fonts can't be taller than about 96 pixels on your Mega. Or about 128 pixels on a Zero or Due.

You can print the Adafruit 7x5 system font in x1, x2, x3, x4, x5, ... but it looks very blocky.
You can print the FreeFonts in x1, x2, ... but you will notice rough edges.


D_P -
thanks for the reply. I am showing the link to the ebay purchase. also, just to be redundant, an image of the chips it says it is or supports. I am using a MEGA 2560 R3.

the free online font modifier only allows 0.96" & 2.4" displays. I had tried it previously.

the stupid MCUfriend.kbv library font_simple.ino results in a blank bright screen. I had previously looked into the Free Fonts. as nearly as I could tell, they only went as large as 24pt.
I have got this font working on my oled 128x64 0.96" display u8g2.setFont(u8g2_font_logisoso58_tf); it is 58pt. and is about 10 mm high. and it contains a degree symbol.
It is almost large enough to do the job, but something about 70pt (13mm) would be better. but I can’t get this font to work on my 3.5" lcd because the font isn’t supported by the chip.

I only need numbers in this very large font. I can fadge in the degree symbol from other smaller fonts, and the same with smaller text for wind direction.

yes, i tried the 2x, 4x etc., and it looks bad. as you can see, i have done more than just hit a roadblock and cry for help.

Thank you again for thinking about my issue and sending along a thoughtful reply. I hope you will give it some more consideration.
If it comes down to buying another 3.5" lcd tft that is ili9481 only (one that works with adafruit GFX), i will do it. Indeed that is what i was trying to do when i ended up with the one i now have. even the one on banggood linked to by edu8s.tv youtube video (which he said was 9481) turned out to be 9486 when you read the product details.

MCUfriend.kbv library font_simple.ino results in a blank bright screen. I had previously looked into the Free Fonts. as nearly as I could tell, they only went as large as 24pt.

You should install MCUFRIEND_kbv and Adafruit_GFX via the IDE Library Manager.
Your RM68140 screen should work straight out of the box.

The SQUIX site can select Size=96 and Library_version=Adafruit GFX Font
You always get a full 0x20-0x7E font. There is no option for selecting numeric or extended fonts.

The GFX Fonts are accepted by all the Adafruit_hardware libraries e.g. Adafruit_SSD1306, Adafruit_ILI9341, Adafruit_HX8357, ...

Ebay vendors lie through their teeth.
Your link shows photos of a parallel Uno Shield.
It has "code" for an SPI ILI9481
It does not mention RM68140. ili9481 ili9468, ili9488 hx8357, or r61581 are popular controllers. But HX8357-B HX8357-C HX8357-D have significant differences.

Explain what you want an enormous font for.


I believe I did install them using the manager, but i will go thru the process again.

I will carefully read again what you said. At first reading i don't understand some of it.

As to why i want the large font, two months ago one of my house water lines ruptured and leaked for nearly 30 days. My water bill went from about $10/mo to $177.

I decided to monitor the line pressure. any significant outflow drops the line pressure. This seemed like a perfect use for an arduino. so i bought a water line pressure sensor that will work with an arduino, set up my wireless data transfer, and got to the last step - setting up the LCD readout.

I want to be able to read it from anywhere in my house in a direct line of sight. if i have to go into my lab to read the pressure, days may go by before i happen in there. That is how i settled on about 70pt. numbers.

yes, i could just set off a buzzer if the pressure goes low (which i will), but i also get a kind of satisfaction in seeing my setup silently working away while i'm staring at my tv.

It’s coming right along now. See attached image.