FEATURE DISPLAYS & UIS DEFINED BY DEVICES: We are what we use
Gordon Lunn at Bridgetek explores how HMI technology is continuing to progress in a rapidly changing application landscape
n modern electronics design, the human machine interface (HMI) is clearly a critical aspect. Today it is universally acknowledged as one of the key ways by which OEMs can differentiate their products from those of the competition. This is no longer true simply in the consumer electronics space, it also has a great deal of validity in relation to the medical, industrial automation, domestic appliance, retail and hospitality sectors too. In general, it is now the HMI that defines the user experience associated with electronic products and equipment - the look, the feel, the responsiveness. If the HMI is appealing then more people will be willing to buy the product and it will be a commercial success. For those operating some form of equipment within a working environment, a well thought-out and effective HMI can boost productivity and result in less chances of mistakes occurring. It can also mean that training up operatives is quicker and easier to accomplish.
I Figure 1:
Bridgetek’s BT815 and BT816 Advanced graphic controller ICs
and generate frustration. Furthermore, this future proofs the design - with provision for new features to be integrated via software, without the need to replace electromechanical components or make alterations to the enclosure. Finally, because of their flat surface, touch-based HMIs are far easier to keep clean - something that is particularly of value in industrial and medical contexts. Bridgetek originally developed its
“The key aspect that EVE relies on is
that rather than the display having to refresh content pixel by pixel, it deals with predefined objects.”
The widespread proliferation of smart displays with touch functionality, first of all in the consumer sector and now increasingly in non-consumer markets too, has been pivotal in HMI evolution. It has allowed more intuitive operation, as well as enabling benefits to be derived from an OEM perspective too. Touchscreens, for example, are able to deliver longer operational lifespans (especially in harsh surroundings) than keypads or an array of switches could ever hope to sustain. In addition, products may become more lightweight, sleeker and have enhanced aesthetic qualities if buttons and LED indicators can be replaced with a touch- enabled display assembly. This approach also leads to far greater design flexibility, with different menus being accessed from a single screen, rather than needing to rely on large numbers of predefined buttons - which are only likely to confuse the user
8 OCTOBER 2018 | ELECTRONICS
embedded video engine (EVE) technology with the objective of assisting engineers to develop more compelling HMIs - without prior experience in this area and with only a very limited number of semiconductor components being required. In doing so, it also opened up the prospect of adding HMI displays to products that had previously only really had the processing resource for simple text displays or LED indicators. This has made greater prevalence of touch- based HMIs possible.
Figure 2:
Functional block diagram of BT815/6
A REFRESHING PERSPECTIVE The key aspect that EVE relies on is that rather than the display having to refresh content pixel by pixel, it deals with predefined objects. This means that the microcontroller processing effort and the quantity of data storage required is markedly less than with a conventional HMI set up. The lower component count has knock-on effects in relation to lowering the overall bill-of-materials costs, reducing the board space required and curbing the system power consumption. It also means that HMI development is much more straight forward and design cycles can be completed quicker.
EVE technology is not standing still, however. There are demands for new attributes to be brought in. What the team found is that once engineers were given a platform on which to construct HMIs, they wanted to push the envelope further and explore new possibilities. Consequently, the memory requirements of HMI designs have increased, so that expansive portfolios of higher quality bitmaps can be utilised. Calls for support of higher display resolutions and sophisticated functions, like video playback, have also become more commonplace.
BROADER FEATURE SET This has led to the need to incorporate a greater breadth of features into the latest generation of EVE devices. Consequently, members of the new BT815/6 series have the capacity to support further compression algorithms to maximise use of their respective 1Mbyte on-chip memories. To supplement this, a dedicated QSPI host port has been added to each of these graphic controller ICs, for attaching external flash memory.
ASTC FUNCTIONALITY Thanks to the adaptive scalable texture compression (ASTC) functionality now incorporated, the graphics processing overhead that EVE HMI systems have to deal with is reduced considerably. This algorithm compresses files so that image quality can be augmented without needing extra data processing/storage resources. Likewise, the smoothness of animations is markedly improved. Finally, given that many OEMs are serving the global market, there is a need for multiple text fonts and characters to supplement standard graphical icons. Application of these has now been made easier, through use of Unicode strings. Touch interaction with technology is on
the verge of becoming totally ubiquitous. With the advent of more advanced semiconductor technology to support their efforts, engineers are now in a position that they can ensure their designs deliver the user experiences that society as a whole has come to expect, while still being practical.
Bridgetek
www.brtchip.com T: 0141 429 2777
/ ELECTRONICS
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