3

While taking apart my EV3 brick I accidently pulled on the ribbon cable connecting the screen to the motherboard too hard and it broke. enter image description here

I figured I could just get a replacement fpc ribbon cable with the same number of pins and swap out the cable, but turns out the other end is soldered to the screen, so that isn't going to work.

I looked around a lot on the Internet and found several other people with the same issue, but no solutions to the problem. Any advice on what I can do from here?

1 Answer 1

4

First of all: before doing anything else, contact LEGO customer support. There's nothing to lose by doing so.


According to the video at https://www.youtube.com/watch?v=gPNJC5Uz9HY , it's possible to replace the screen with a 1.8 inch colour TFT display with the aid of a flat ribbon adaptor.

EV3 with replaced screen, disassembled

I'm unsure if you would need to replace the Lego firmware with https://www.ev3dev.org/ or not.


Edit: Lego offers electronic schematics of the EV3 as part of the "Hardware developer kit" that can be downloaded from https://education.lego.com/en-us/product-resources/mindstorms-ev3/downloads/developer-kits . It tells us that the display connects through SPI, and contains this diagram of special relevance:

Wiring diagram for the SPI ribbon cable

You should be able to connect any SPI display, which would need 5 connections: +3.3V (or VDDA), 0V (or GND), clock (CLK), MOSI (or DIN or RX in a SPI peripheral), and CS (or SS). Be aware that the nomenclature for SPI is confusing. The screen does not send data back to the board, so a MISO/DOUT/TX connection is not needed.

The stock firmware should work with any monochrome SPI display, but we hobbyists cannot offer you any guarantee at all.


Anyway, the original screen seems to use a pretty standard 18-pin 1.0mm-pitch ribbon cable. You should be able to unsolder it and replace with a new one. But since the connector at the board is a 18-pin 0.5mm-pitch, you'd need to use an adaptor like the aforementioned one.

Bear in mind that soldering tracks with a 1.0mm pitch requires precision soldering skills (and you can imagine that 0.5mm pitch will just be harder). I strongly recommend practicing your soldering skills first.


Edit: According to the folks over at the Electronics stackexchange, it's possible to repair a flat ribbon cable.

5
  • Thanks for your reply Ivan. I did go through that video earlier and it seems like the stock firmware doesn't support the color LCD display. I wanted to know if it was possible to get a screen that is similar to the existing one and works directly with the stock firmware. I'm not very experienced with electronics like these so it'll be quite difficult for me to figure out what wiring goes where, but I'm open to learning.
    – dkapur17
    May 29, 2023 at 11:39
  • I think I added enough information about wiring to get you started. May 29, 2023 at 12:32
  • Yes. The added information is of great help. I’ll do some more reading on this and get back to you. Thanks a lot!
    – dkapur17
    May 29, 2023 at 12:39
  • I was also wondering if screen size would be an issue. The stock display has a resolution of 178x128 pixels, which seems to be custom designed for the EV3, and I can't find that screen size anywhere. The closest I can find is a 160x128 pixel display. I'm assuming that the EV3dev kernel can adapt the display contents to the screen resolution, which is why it worked with the adafruit 160x128 LCD display (in the video you linked), but I'm not sure if that is the case with the stock firmware. Any idea about this?
    – dkapur17
    May 29, 2023 at 14:07
  • 1
    Alas, I haven't worked enough with SPI displays to know that. You might wanna ask in electronics.stackexchange.com . May 29, 2023 at 17:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.