Technical requirements to support a target platform

Description:

This article describes the minimum requirements of a target platform to run an Embedded Wizard Platform Package and an Embedded Wizard application. Even if EmWi can do all drawing operations in Software, this article provides also a list of helpful graphics acceleration functions to improve the performance.

 

Solution:

Minimum requirements:

- 32 bit CPU with more than 100 MIPS

- pixel based frame buffer

- possibility to allocate and free memory

- access to one timer

- optional: graphics acceleration

 

Helpful functions:

The following part describes a list of functions, which are helpful from Embedded Wizard point of view to increase the performance of the Graphics Engine. (1) and (2) are the classic DMA features (fill and copy), the other functions requires more H/W acceleration, however, they would save a lot of the required CPU time compared to the pure Software processing.

 

(1) Fill

Filling of a 'rectangular' memory area with a constant color value with the following parameters:

- Start Address

- Width (number of pixel to draw)

- Offset (number of pixel to skip)

- Height (number of lines)

- ColorValue (32 bit)

 

(2) Copy

Transfer of a 'rectangular' memory area into another 'rectangular' memory area with the following parameters:

- Destination Address

- Source Address

- Width (number of pixel to copy)

- Destination Offset (number of pixel to skip within destination)

- Source Offset (number of pixel to skip within source)

- Height (number of lines)

 

(3) Copy with Alpha Blending

 Transfer of a 'rectangular' memory area into another 'rectangular' memory area with an alpha-blending operation. The parameters are the same as in (2). During the transfer, each source pixel is combined with the destination pixel in the following way:

Cd = Cs * as + Cd * (1 - as)

ad = 1 - (1 - as) * (1 - ad)

 

Cd: Color of destination pixel (= R, G, B value)

Cs: Color of source pixel (= R, G, B value)

ad: Alpha value of destination pixel

as: Alpha value of source pixel

 

Remark: The formula is written for ranges 0...1 and has to be adapted to range 0x00 ... 0xFF.

 

(4) Copy with Alpha Blending and Global Alpha

Additionally, it could be helpful to have (3) with an additional global alpha value, which is multiplied with each source alpha value.

 

(5) Fill with Alpha Blending

Filling of a 'rectangular' memory area with a constant color by using an alpha-blending operation.

 

See also:

 

Keywords:

Requirements, technical, specification, function, performance, graphics acceleration