AN3128 datasheet(19/105 Pages) STMICROELECTRONICS

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AN3128

Multi-input embedded GUI library

Doc ID 16918 Rev 5

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3.4

Library architecture

Library architecture is thought out and developed in two separate layers:

●

API layer

●

HAL layer

This layer architecture improves the code re-usability splitting the application programming

interface code (fully portable and re-usable) from the hardware abstraction layer code

(hardware dependent and written upon the LCD library).

Figure 5.

Firmware library architecture

3.4.1

API layer

The application programming interface layer allows the final application to use the library as

a black-box. The library firmware encapsulation feature and exported API allow a full control

of the LCD and touchscreen without knowing, in-depth, LCD registers and SPI/I2C

read/write operation steps for the LCD and touchscreen respectively.

●

The API layer includes the following files:

–

graphicObject.h

–

graphicObject.c

–

graphicObjectTypes

–

cursor.c

–

cursor.h

See Section 4.1 for a more detailed description.

3.4.2

HAL layer

The hardware abstraction layer is directly built into the specific LCD firmware library and

allows the build-upon layers, like the API layer, to implement its functions without knowing,

in-depth, the LCD, MCU and touchscreen controller used. This improves the library code re-

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