International Appliance Manufacturing 2008 - (Page 42) Collaboration brings User Interface design flexibility This brings us to our second obstacle in the migration to an ARM7 based GUI platform for embedded control systems. Most GUI solutions are designed to run on powerful operating systems derived from the desktop. This means that they require considerable computing power and memory that is far beyond the capabilities of the ARM7, and have a price point that is unacceptably high for many embedded applications. If the embedded system falls into this category, the embedded engineer is often forced to code his GUI operating system and tools from scratch. This is not an easy task, but he will eventually make the GUI work. The major challenge with this approach is making the GUI look good. For consumer products, such as washing machines, microwaves, Figure 1: Amulet’s GUI Engine DMA From The Frame Buffer To The LCD via DMA for GUI rendering and LCD refreshing, leaving CAP7’s internal memory and bus free for code execution via the ARM7 processor core. On smaller displays, the internal SRAM can be partitioned into two independent blocks – one connected to the Amulet GUI engine and the other connected to the ARM. This also yields concurrent processor execution and LCD refresh, but with no external memory required – this is a real plus in applications constrained by cost or board real estate. Besides controlling the LCD, Amulet’s custom logic has a GUI engine that manages a graphical user interface, offloading more work from the CPU. Graphic designers can visually design the GUI using standard web-design tools, and then use Amulet’s proprietary development tools to compile the HTML into a special language called microHTMLTM that drives Amulet’s GUI engine. The embedded systems programmer takes it from there by connecting the application data to the microHTML GUI through a simple API that allows read and write access to the arrays of shared data. A connection of the shared variable data to the visual GUI objects is illustrated by the GUI example shown in Figure 2. Figure 2: Connecting The Application Data To The GUI Objects 42 International Appliance Manufacturing 2008
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