Do I really need the exact specified screen?

I didn’t realize before buying that HDMI is not supported with this core board, so am looking to get a screen. The documentation lists a particular screen but I’m having trouble buying it. Is it strictly necessary to use that exact screen? If not, I’d appreciate some recommended alternatives. Don’t need touch-screen functionality, just enough to see what’s going on so I can confirm boot, etc.

Wouldn’t UART be more effective for that?

Potentially but I’m not really an expert and working with a screen is an option I would like to have.

You don’t need to be an expert. The carrier board has a “debug usb” port with a UART-to-USB converter. You just plug a micro-USB wire into the debug port and open it with a terminal program like screen or putty. This also gives you the advantage of beginning output well before the screen would normally come on, so you’ll be able to see WHY it doesn’t start if it doesn’t.

Ok, point taken, but I still want a display for a long list of other reasons. Do you know of one?

Technically, many displays could work with it.

Practically, it looks like there are two connectors on the carrier board; one is on the high-speed connector that is added for mezzanine compatibility with 96boards CE (and therefore some displays for CE may work), and the other is a ribbon connector for raspberry pi displays, suggesting that some displays for raspberry pi may work.

Implementation wise, you have to be careful, since for this type of display, the parameters need to be configured in the kernel, which means that you need to make sure that the display you select has characteristics that match whatever is programmed into the prebuilt kernel (if any!!!), or you’ll have to implement it yourself. And obviously, you’ll also have to verify that the MIPI interface on the board is capable of driving the display that you select.

The bottom line is this; you purchased an IoT board, and such boards are generally NOT EXPECTED to have a display connected to them. I believe that, given your concerns over just attaching a debug cable, that this will be more of an uphill battle for you than you are prepared for. If you want something with a display, you should have purchased the other SoM with rk3399 or a CE board rather than this. I suspect that a Dragonboard 410C would be a better fit for you, and a lot less expensive.

To be clear I had already configured the board to show CPU debug output over UART before starting this thread. I’m not an expert but I’m also not scared to try these things since it’s my job. It seems to me that this board is expected to have a display attached for some applications since it’s built for Android development and the devs go to the trouble of specifying a screen. Ultimately there will be no screen connected since once I have a Linux build successfully booted* and connected to my network most things will get done over SSH. But you can’t deny the convenience of having the option of a display during development, troubleshooting, etc.

I guess I need to qualify my question a bit further and ask if anyone knows of a screen that will work with either or both of the provided prebuilt images. It seems like your answer is no.

*That’s another problem which you may have seen me post about in another thread. The Sept 2020 image doesn’t appear to boot at all, as evidenced by the UART output.

Where does it say that?

And there is a big difference between CAN and EXPECTED TO. Your car CAN jump like the dukes of hazard, but that use isn’t covered by manufacturer’s warranty.

I also CAN deny the “convenience” of a connected display – when it gets in the way – either physically, or it impedes beneficial work, as it would be for what you are describing. If you “ultimately” will not have a screen connected, then there is no benefit to attaching a screen, since the same interface can be obtained over UART and SSH, therefore you are wasting time trying to attach a display that won’t help with anything, and falling behind in progressing towards your actual objectives.

I mean the 2019 image is an Android OS, and the intended screen is a phone-style touch screen. Maybe “built for” is the wrong phrase but it’s clearly an anticipated use case.

I’m not trying to be rude here but it’s a simple request and if you don’t want to answer it I don’t think we have much more to talk about. I appreciate you’re trying to help and I’m grateful for your advice but for now all I want is for someone to tell me, definitively either way, if they know of another screen I could use. I don’t need someone to pick apart my workflow when they know nothing about it.

I doubt that you’ll find anyone who can suggest a screen as definitely supported besides the one you say is listed in the documentation. But as I’ve stated, there are screens around with compatible physical interfaces, but I can’t comment about whether or not the software would work with them.

And I’m asking about references to android for this board out of curiosity rather than being argumentative. I personally have not seen ANY references in the documentation to android, nor does there appear, at least anywhere I’ve looked, that there is an android image for it. It really would not make sense for this hardware.

Are you positive that you are looking at documentation for the TB-96AIoT and not the TB-96AI? The latter SoM is rk3399, supports HDMI output, and Android, but it is not the SoM you tagged in this thread, which has just the extra 2 little characters on the end to distinguish it.

It’s true that it’s not made very clear, and honestly if I had realized beforehand I may have chosen a different board. The image labelled TB-96AIoT-images-npu1.3.2-20200923, which you can find by following the Downloads link from the product page, though not labelled as such, is an Android image. The only other image you will find doesn’t work at all (based on UART output, see my other thread) so I don’t know what that is but I suspect Android as well.

Of course there is the bulidroot option but I’ve never built Linux before so without even understanding why I can’t get that other image working I don’t really fancy my chances. That is (probably) the plan eventually but I don’t want to put too much work in that direction until I can confirm the board can do what I need. Nevertheless I am planning to take some baby steps in that direction this week and we’ll see what happens.

I find it surprising that no one can answer the question. Do the manufacturers/developers ever post here?

Some manufacturers do, and some don’t. Hit or miss, usually miss. The people who work for Linaro/96boards do often, but their work doesn’t necessarily align with the vendor.