Decent display, but lack of technical documentation is a bear
Reviewed in the United Kingdom on 12 December 2019
This is the "official" Raspberry Pi touch-screen display and, as such, I expected a high level of technical documentation. It turns out, there was none at all. It isn't very clear, for example, even which way the short ribbon cable attaches to the PCB headers. Is isn't clear whether you need to connect the I2C pins on the display to the Pi -- I believe some Pi boards need this, and some do not (mine, it turns out, does not). It isn't clear what kernel modules are needed to handle touch input and brightness control, etc. It isn't clear what extent, if any, it is possible to use this display and the HDMI port at the same time, or even to switch between them at runtime. It isn't clear whether you can change the display resolution, either at boot time or runtime. It isn't clear what the maximum current consumption of the display is, which is a really big deal if you're building something battery-powered. And so on. What little documentation there is assumes you're running one of the stock Raspbian Linux releases. If you're building something custom you're really, really on your own. There are various Rapberry Pi forums that have some technical information, but it is conflicting and, in some cases, just plain wrong.
I just bought a cheap, 3rd-party OLED display for a Pi for a few quid, and it had better technical documentation than the official display. This, frankly, is extremely disappointing when you're working with an official add-on for a device that is marketed for experimenters.
Having actually got the thing working -- which took quite a few hours with Google and a lot of trial-and-error, it turns out the display quality is pretty good. At the stock resolution text is pin-sharp. There's a good range of brightness adjustment, right down to zero. Touch input is responsive and accurate. Viewing angle is OK, for a small display. It's generally cool-running. Construction seems pretty robust.
However, there are some other oddities, quite apart from the shocking lack of documentation.
It's nice that the Pi can be mounted directly on the back of the display, for experimenting purposes, even if that isn't how things will eventually be assembled. However, if you do mount it this way, it's very fiddly to get the Pi SD card in and out, because it's underneath the ribbon cable.
There are four mounting points on the back of the display, presumably for panel mounting. However, these points are slightly proud of the back of the display. What this means is that if you try to panel-mount the display, and use the built-in mounting points to secure it, the bezel will stand off the panel by about 2mm. This really doesn't look very professional. I'm still trying to find a more elegant way of panel-mounting the display.
There's an awfully large bezel around the viewing area -- if you are panel-mounting, you're going to need a much bigger panel than the viewable area of the display would suggest.
If you switch off power to the panel at runtime, the picture doesn't come back when power is restored. This, unfortunately, puts paid to my plan of having a hardware on/off switch for the panel, to save power. You can still control power in software but, where power management is concerned, there's no substitute for a big switch.
In short, this is a pretty decent display if you want to make a sort of mini-tablet using the official Raspbian Linux distribution and a stock case, and have little concern about interfacing, current consumption, panel mounting, etc. If you want to build something custom, and really need detailed technical specs, you'd probably do better to buy a 3rd-party display which, ironically, is likely to be better documented.
Sad, very sad.
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