In addition, functional blocks supporting high-performance graphics effects such as perspective transformation, as well as built-in multi-channel stepper-motor control for conventional dials, are valuable features that help to create a strong all-in-one microcontroller suitable for the task.
Graphically rendering the rotating pointer of a virtual dial is a complex undertaking, since the end result must be lifelike and visually pleasing to the user in order to be acceptable in the automotive marketplace (figure 2). Care must be taken, for example, to avoid unwanted stroboscopic effects which can be distracting for the driver and will attract unfavourable comparisons with conventional dials. Toshiba has overcome this challenge with the patented stroboscopic compensation feature in its Capricorn-Bt0/1 all-in-one microcontrollers, which are designed specifically for automotive advanced instrumentation applications. The stroboscopic compensation is based on a hardware bitmap rotation block, which handles overlaying of the rotated pointer onto a graphical background with angular resolution as fine as 0.1°. A filtering algorithm is implemented to optimise the appearance of the pointer.
The Capricorn microcontrollers also integrate stepper-motor control interfaces, thereby providing the flexibility to support projects combining advanced graphical effects with conventional physical dials.
Figure 2. Rotated pointer as an overlay.
Inside the Graphics Engine
To help manage system cost and provide flexibility for manufacturers to differentiate products for various market sectors, some of the microcontrollers in the market today provide special features that help minimise memory requirements and boost performance when a low-cost display