Link copied to clipboard!

BT817Q display controller – Putting EVE4 into practice

Back to top

The Bridgetek’s BT817Q controller on Riverdi display board is the most powerful member of advanced graphics controllers family targeted at embedded applications for generating high-quality Human Machine Interfaces (HMIs). Let’s look at a few situations where using the new EVE4 solution gives most benefits:

Building a new device from scratch

If you are a constructor, an engineer or a programmer who needs to build a device with a display, the use of a classic display with RGB, LVDS or MIPI interface without a controller requires a lot of work on your part. Not only a lot of programming work, because you literally have to handle every single pixel on this display, but also a lot of hardware work because the display must be properly connected. You need to have a display controller on your board, a piece of hardware most often, which works in such a way that it refreshes the screen dozens of times per second and opens literally every pixel. This data is transmitted between the display and the controller all the time: several dozen times, sometimes several hundred times a second, with high frequency. You need all this image memory, this image generation on your side – this is a lot of work. There are, of course, mechanisms today to facilitate this. You can use a modern processor with a controller and you can use a graphics library. There are some very good and free libraries available online which allow you to generate this intelligence.

However, it still does not release you from building hardware; from buying an expensive processor with a controller and connecting it in close proximity to the display through RGB or LVDS interface. It requires a lot of experience and a lot of work.

Adding an intelligent controller BT817Q to the display takes a lot of responsibility from you. So both; your hardware (PCB, processor etc.) and your software can be much simpler because the graphics library has been moved to the display control and is already in the display. Therefore, when communicating with the display, you communicate through a simple interface such as SPI (a relatively slow peripheral) used to send commands only. You can send a picture too, but it is usually sent only once. The intelligent controller BT817Q has a built-in memory where it stores these pictures and after loading them once into the memory, they are then recalled with the help of commands: ‘display this’, ‘show this’, ‘move’, ‘rotate’ etc. We can create various advanced graphics just with commands so there is a lot less work on your part here.

Let’s look at a coffee machine. In its internal memory, it will have pre-installed icons of coffee types, cup sizes, additives etc. These icon are then being displayed depending on the commands given i.e. ‘small, white cappuccino’.

Upgrading an existing device

What if you already have a device with an older display, e.g. monochrome, two-color, two-line etc.? How can BT817Q controller help then?

Let’s go back to our coffee machine. It makes various types of coffee perfectly well and does not need to be changed but it has a small, black and white, non-touch display while we want it to have a color touchscreen. The easiest way to proceed is to use an intelligent display that will generate graphics.

We have customers who did not change anything in their coffee machine because it already had a very popular SPI interface and it was enough to just connect it to a modern, color display with a touchscreen. They suddenly had a brand new machine with the same hardware inside.

So, as a company, you do not have to invest in anything new, you can use even the same PCBs, perhaps with some slight modifications but you can use the same processor as before. Here, they used almost the same program for handling the machine just simply adding a new display to their SPI interface. Alternatively, you can add a relatively simple program that will display the new menu and icons on the screen and handle it from the user interface side.

In this situation, if your PCBs are certified and you have an SPI interface, you do not need to recertify it. It is a great advantage if you have programs developed over many years and are used to your CPU, to a certain programming environment. Now, you can just add a color display.

Today, thanks to the EVE4 series, the use of an intelligent display is possible even with the oldest and simplest processor. No matter how slowly the commands are being sent, you can even view movies displayed from the internal memory. They are uploaded once, during the production of the display, and then just played which is why the speed of the processor in this case is of no consequence. That’s what these smart displays are for.

Solving an issue

There is another scenario; where a customer cannot place the display next to their electronics.

If you have a small, non-intelligent, RGB display of 3,5″, 4.3″, 5.0″ or 7″ without a controller, it most likely will have a short interface and needs to be connected directly to the electronics. There are scenarios where this is not possible and for some mechanical reasons the display needs to be further away from the electronics, for example, electronics are on the back of the device and the display is on the front. On a small RGB display, it is the addition of the controller to the display that gets us the longer SPI interface between our electronics and the display. It can be several centimeters long so there are also customers who decide to use an intelligent display not because it is easier, which of course is also an advantage, but primarily, because of mechanical reasons.

To sum up, thanks to our usage of the Bridgetek’s BT817Q chip, this is a display set up that can be easily added to a device without moving the electronics and having the display on the front regardless of whether there was an older display before or none at all.

Learn more about EVE4 solutions here or browse the EVE4 line directly here.

See products