I2C Screen Finder: Specific Size and Configuration

[re_b]

Hello everyone,

I am looking for a screen working in I2C with particular specifications.
I would like to find a screen that can be configured with at least 3 different I2C addresses.

As for the dimensions, I'm looking for a screen whose total size, including the PCB, would ideally be 7.5cm by 4.2cm.
However, I also want the viewable part of the screen to be at least 6cm by 3cm.

I've been searching online, but haven't found any screens that match this criteria yet.

If you have references to offer me.

Thank you in advance for your help !

[Koepel]

Hello,
Can you describe your project ? Please give us a broader view.

Do the three displays have to fit in a box ?
What kind of display ? LCD, color, TFT, OLED, Nextion ?

[re_b]

my project is in interface and 3 to 6 screen on a microcontroller.
my microcontroller has 2 separate i2cs so no problem if the screen only has three addresses.

each screen will be in an independent box but which can connect to the other, with a box that will be the motherboard.

the boxes will be made by 3D printing so can be modular but for a question of aesthetics the dimensions given previously are appreciated.

I don't have a specific brand to consider, for the colors I prefer white but if there is the possibility of having it RGB it would be a plus.
and a constraint that I had forgotten to be able to display text or an image
the touch option does not interest me

[Koepel]

Can you tell what your project is about ? What is it for ? Please give us a broader view.

With a broader view I mean for example this: Each employee gets a display on the desk telling when to take a break, and the length to each desk is about 10 meters.

Which microcontroller do you plan to use ?

For simple and slow LiquidCrystal displays, you can use a software I2C bus. By combining the SCL signal, you only need 7 pins for 6 displays at the same address.
Here are 30 I2C buses in Wokwi simulation: https://wokwi.com/projects/307886580731740737

In most cases, a I2C multiplexer is used: https://www.adafruit.com/product/2717

How far are the boxes apart ? The I2C bus is not supposed to go into a cable. It is not that kind of "bus". If the total length of all the pieces of the I2C wires are 1 meter or less, then it might be possible.

For 6 Nextion displays, you need 6 Serial/UART ports. Perhaps SoftwareSerial or a multiplexer is possible.

How slow may it be ? The E-paper displays are beautiful: https://www.adafruit.com/product/4778.

At this moment, it might go in the direction of an Arduino board in each box and RS-485 between them.

[re_b]

I saw this if not long ago I wanted to reproduce it but in a modular way with more information

pour le microcontrôleur je compte utiliser une STM32 L4

the caps will suddenly be a few centimeters
for the speed it doesn't have to be fast since one refresh per minute will be enough for me

I intend to keep i2c because there are sensors that work with such as temperature and humidity
the advantage of I2C would have allowed me not to have a lot of cable

I was not aware of this screen but I see that it is very pretty but unfortunately in spinnaker what I would like to avoid

[PaulRB]

@re_b

the caps will suddenly be a few centimeters

Please try that again with different words.

@re_b

spinnaker

That's a type of sail.

You can get white 7- and 14-segment led displays. You can drive these with HT16K33 chips, which have i2c interface and up to 8 of them on a single bus.

[re_b]

@PaulRB

Please try that again with different words.

the cables will only be a few centimeters long

@PaulRB

That's a type of sail.

I said that I found this screen pretty but that unfortunately it is in SPI and that I would like to keep i2c

7 segment screens work well but unfortunately I don't have the possibility to draw on them to display a picture

[PaulRB]

HT16K33 can also control 2x 8x8 led matrices. You could display simple pictures with those.

[PaulRB]

There are i2c backpack boards for 128x64 graphic LCD displays:

These backpacks can have 8 different addresses, set by the 3 pads A0, A1, A2:

[re_b]

I had already thought of the LED matrix but I did not find it detailed or aesthetic enough

and for this last chip I think it's my solution I knew it but thought it was only used for 7 segment displays

and I also retain this solution in case

@Koepel

At this moment, it might go in the direction of an Arduino board in each box and RS-485 between them.

thank you for the help provided

[PaulRB]

@re_b

and for this last chip I think it's my solution

Wait! I just noticed that the chip in those pictures I shared is not the one I thought it was. It is a pcf8574. I did not know that this could be used as a backpack for 128x64 LCD and I am not sure if it would work well. I have backpacks for 128x64 LCD but they use pcf8575 chips. Make sure you buy this type. In fact, I suggest you buy 2 only and see if they work well enough for your project before buying 6.

EDIT: it is possible I am mistaken and the backpacks I have use MCP23017 chips. Either MCP23017 or PCF8575 would be ok. These are 16-bit I/o expanders. PCF8574 is only 8-bit.

[re_b]

oh thank you i would have been had

but yes my objective is still to test with the minimum possible

[PaulRB]

No problem.

I just checked and the backpacks I have are MCP2017.