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Display System with Programmable Graphical Layers and Fixed Priority

IP.com Disclosure Number: IPCOM000211120D
Publication Date: 2011-Sep-20
Document File: 5 page(s) / 726K

Publishing Venue

The IP.com Prior Art Database

Abstract

In automotive cluster applications the display image is actually a combination of various layers. At any pixel depending on the layer priority a particular higher priority data is displayed. The more layers supported in the system, the more bandwidth support is required such that the bandwidth becomes the blocking parameter for the display systems. This paper discusses an intelligent priority calculation scheme that operates in a single clock cycle and solves the dependency on the bandwidth.

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Display System with Programmable Graphical Layers and Fixed Priority

Abstract - In automotive cluster applications the display image is actually a combination of various layers. At any pixel depending on the layer priority a particular higher priority data is displayed.  The more layers supported in the system, the more bandwidth support is required such that the bandwidth becomes the blocking parameter for the display systems. This paper discusses an intelligent priority calculation scheme that operates in a single clock cycle and solves the dependency on the bandwidth.

Automotive cluster applications require display controllers that have the capability to overlay important information on different backgrounds.  Figures 1.1 and 1.2 show a typical display system (TFT) used in high end cars. For displaying fuel level and speed related information, data is continuously monitored by the sensors and the relevant numeral image from the graphics ram is displayed. Similarly, static images that are used to display icons on the TFT display are stored in the graphics ram.

                                                            Fig. 1.1

A priority mechanism must be used to display layers/messages according to a most critical requirement. For example, if the fuel level is below a certain threshold, the sensor should indicate this condition to the processor to display this emergency information on the dashboard. The paper discloses asystem that reduces the system bandwidth by fetching only the relevant layer data from the system memory.  

                                                                                             Fig. 1.2

Earlier solutions fetch data for all the layers and later discard the lower priority data, thereby wasting critical bandwidth necessary for high end graphics applications, thereby limiting the solution to only smaller displays.  Prior solutions fetched data for all the layers and then overwrite lower priority data with higher priority data. For example, if N layers are enabled for full display size then the bandwidth used will be N times. 

The proposed solution first uniquely arbitrates among the layer and then only fetches the higher priority data. Since for each pixel only one data is fetched after arbitration the bandwidth requirement is considerably lower.

Since arbitration is performed on each pixel, it is essential that the complete combinational logic should work in a single clock cycle to provide the capability to position the layer at a pixel boundary.

We also have implemented a unique algorithm that reduces the number of muxes required to implement the arbitration logic.  Below is a comparison between the two schemes.

Scheme 1:  Without logic reduction algorithm the total no. of muxes is (N-1)*N/2 . For 16 layers it is 120 muxes.

If (A_a...