What’s the best display you can use in your Raspberry Pi project? To answer that question you will in fact need to answer a few smaller questions before and I’m afraid it boils down to the usual “It depends!”.
This article mostly applies to the Raspberry Pi B+ and above layout although many of the considerations above are also appropriate for other models.
Choosing a big or a small display, connect it via the HDMI connector or via the GPIO pins, needing touch capabilities or not, these are only some of the decisions you’ll have to take depending on your end goal. Ultimately it will be a trade-off with what will your project requires and what’s left on the platform to connect and drive a display.
The Raspberry Pi can be connected to a display in several ways. Typically you will use:
- Composite Video
HDMI gives you plenty of choices in terms of traditional computer monitors and TV set. Anything that has an HDMI input will most certainly work for you.
A few vendors offer displays kits which allow you to assemble screen, controllers and extra bit and pieces to build your own display. These are particularly indicated for projects that will require a screen to be mounted onto custom design case or frame. Examples of these are the Watterott 7″ 800×480 HDMI Display with resistive touch or the Pimoroni HDMI 10″ LCD Screen Kit (1024×768).
With Adafruit you get screens from 4″ to 10″, resolutions 800×480 to 1280×800 and in some cases a resistive touchscreen and/or additional control buttons.
Adafruit like others offer kits with standard laptop-like LCD screens together with controllers that offer not only HDMI input but also VGA and Video Composite. Some of these controllers can support other LVDS screens but 9 out 10 it is more a myth than a real possibility so I wouldn’t count on reusing the LCD of your old laptop any time soon. Still this is an interesting possibility and provides good flexibility for your project.
These LCD displays from Waveshare for example come in many different sizes (from 2.8″ up to 13.3″) and some offers mounting holes for the Raspberry Pi, BB Black and other platforms. They offer good resolutions from 480×320 all the way up to HD.
As I was browsing around for this article are I also found Uctronics which seem to provide its own line of displays, Osoyoo sells a very similar display too. In both cases the displays seem to be able to offer the audio from the HDMI input as a separate analogues 3.5 mm jack and connect to the GPIO of the Raspberry Pi providing both a way to support the display and connectivity for the SPI touchscreen. Both 3.5″ displays offer a resolution of 480×320 at 60 fps and can accept input of anything between 480×320 and 1920×1080. The two displays look spookishly similar …
several others instead use a cloned or rebranded version of a display called XPT2046 coming somewhere from China. It is a 5″ display, has a 800×480 resolution, a resistive touchscreen and seems to be supported at least in Raspbian. You can find more details via Elecrow’s Wiki.
It must be said that a few of the products featured by some vendors are either clones or rebranded products so shop with care!
Connectors and adaptors
HDMI connectors are generally fairly cumbersome and unless you get a custom HDMI connector made for a specific assembly as shown above, in some cases you might want to consider using ribbon cables like the ones you can put together with Adafruit DIY HDMI Cable Parts.
If however your are going to use a traditional monitor it might happen that it supports other standards rather than HDMI. Not many realise that HDMI can also be connected very easily to DVI and VGA monitors. If you have one of these displays sitting around you can use an adaptor for the DVI or a converter for the VGA. In both cases you might need to end up using the 3.5mm jack on-board the RPi for the audio or better use a dedicated audio card (HAT, pHAT, etc.) although some adaptors/converters can offer a dedicated audio jack straight out of the HDMI port.
If you would prefer to instead use a Displayport you will be able to easily find HDMI to Displayport adaptors. The standards are practically one and the same so no problems here either.
As far as I know the only display available that can be connected to this port is only the official Raspberry Pi Display.
As highlighted in this article released by the Raspberry Pi foundation on the launch day this 7″ display offers:
- RGB 800×480 display @60fps
- 24-bit colour
- FT5406 10 point capacitive touchscreen
- 70 degree viewing angle
- Metal-backed display with mounting holes for the Pi
There are now a few cases that allow for a neat assembly of the display, the RPi and HATs or additional hardware. Pimoroni – Flotilla Frame, ModMyPi Case and Stand, oneNineDesign Case and other more or less pleasing designs which offer similar
and more customised solutions like the one from M2P for the iQuadIO board.
There are many DIY solutions also offered on Thingiverse too if you have the tools and the aptitude.
My favourite though remains the SmartiPi case .It comes with or without LEGO studs and has recently added a back cover which provides protection to HATs and add-on hardware. Overall it has the best design and offers most of the features you will need.
There is a great article form Average Maker which covers pretty much all the cases commercially available out there which is well worth reading if you’d want to know more on Raspberry Pi Official Display cases.
You might wonder why was the Composite Video option ever offered in the first place. Despite the great success it has received the Raspberry Pi has humble origins and at its heart it was designed to be inexpensive. It was thought that providing Composite Video would have allowed in many countries that still rely on old TV set to use the Raspberry Pi without the need to purchase a dedicated monitor as it was the case with the first personal computers back in the ’80s.
So aside from being able to use old CRT TV sets, projectors, etc. what else is there for this type of output?
Adafruit sells very nice, neat, small NTSC/PAL displays from 1.5″ up to 7″. They are cheap and cheerful displays with no touchscreen or much else but they are good to keep the budget low although they are not that cheap after all.
The downside of using Video Composite is the resolution (NTSC 720×480 60Hz interlaced – PAL 720×576 50Hz Interlaced) you will get and in general the low quality of the pictures. Depending on where you live you will be bound to the limitations of NTSC or PAL and nowadays those resolution are fairly small for some applications.
Where on the old 26 pin RPi you would have needed an RCA cable for the more modern ones you need a 3.5mm jack to plug into the A/V port which used to be just used for audio previously.
There is a nice article from Raspberry Pi Spy about the connector if you are interested.
As for which cables to use the on in the picture is probably what you will need. You can get one here.
Screen Capture with Video Composite
There are many methods most of which are software based to capture the screen but there are times in which a hardware solution works best. HDMI capture kits are becoming cheaper but one good use for the Video Composite output would certainly be to use an inexpensive capture kit to record whatever you do on you RPi.
This can be useful for teaching, creating a video tutorial, capture screen snapshots, etc.
There are literally tons of these cards a lot of which USB, some are actually even compatible with the Rasbperry Pi meaning that you can capture using the RPi as the recording station. So you could end up recording a Pi with a Pi 🙂 weird!
In the next article I will go through the additional options (GPIO and USB) and go through further considerations on display technologies.