GFX_DISPLAY_BUFFER_LENGTH Macro

Microchip Graphics Library

#define GFX_DISPLAY_BUFFER_LENGTH 0x00025800ul            // <COPY GFX_GCLK_DIVIDER>

Overview

The following are additional Hardware Profile macros used when using the driver for the Microchip Graphics Module that comes with the PIC Microcontroller (PIC24FJ256DA210 Device Family) (PIC24FJ256DA210_DEV_BOARD).

When using internal or external memory
- GFX_GCLK_DIVIDER - Set the clock divider for the pixel clock.
- GFX_DISPLAY_BUFFER_START_ADDRESS - Set the Display Buffer location.
- GFX_DISPLAY_BUFFER_LENGTH - Set the Display Buffer length (size) in bytes. This is calculated by the display's width*height*(color depth/2).
When using external memory only. External memory may be placed in chip select 1 (CS1) and/or chip select 2 (CS2) regions. Refer to EPMP Family Reference Manual for details on how to use EPMP for graphics applications.
- GFX_EPMP_CS1_BASE_ADDRESS - Set the location of the external memory mapped to the EPMP CS1.
- GFX_EPMP_CS2_BASE_ADDRESS - Set the location of the external memory mapped to the EPMP CS2.
- GFX_EPMP_CS1_MEMORY_SIZE - Set the size of the memory mapped to the EPMP CS1. This value sets how many EPMP address lines will be used.
- GFX_EPMP_CS2_MEMORY_SIZE - Set the size of the memory mapped to the EPMP CS2. This value sets how many EPMP address lines will be used.

If the display buffer is located in external memory (i.e in PIC24FJ256DA210) then the memory requirement for the graphics use must fit into the chip select region size. The table below summarizes the requirements.

Buffer Name	Enabled Features	External Memory Required	Display Buffer Location
GFX_EPMP_CS1_MEMORY_SIZE	none	EQ1	chip select 1 region.
GFX_EPMP_CS1_MEMORY_SIZE	USE_DOUBLE_BUFFERING	EQ2	chip select 1 region.
GFX_EPMP_CS1_MEMORY_SIZE	USE_DOUBLE_BUFFERING + USE_COMP_IPU	EQ3	chip select 1 region.
GFX_EPMP_CS2_MEMORY_SIZE	none	EQ4	chip select 2 region.
GFX_EPMP_CS2_MEMORY_SIZE	USE_DOUBLE_BUFFERING	EQ5	chip select 2 region.
GFX_EPMP_CS2_MEMORY_SIZE	USE_DOUBLE_BUFFERING + USE_COMP_IPU	EQ6	chip select 2 region.

Equation	Description
EQ1	GFX_EPMP_CS1_MEMORY_SIZE >= GFX_DISPLAY_BUFFER_LENGTH
EQ2	GFX_EPMP_CS1_MEMORY_SIZE >= (GFX_DISPLAY_BUFFER_LENGTH*2)
EQ3	GFX_EPMP_CS1_MEMORY_SIZE >= (GFX_DISPLAY_BUFFER_LENGTH*2) + GFX_COMPRESSED_BUFFER_SIZE + GFX_DECOMPRESSED_BUFFER_SIZE
EQ4	GFX_EPMP_CS2_MEMORY_SIZE >= GFX_DISPLAY_BUFFER_LENGTH
EQ5	GFX_EPMP_CS2_MEMORY_SIZE >= (GFX_DISPLAY_BUFFER_LENGTH*2)
EQ6	GFX_EPMP_CS2_MEMORY_SIZE >= (GFX_DISPLAY_BUFFER_LENGTH*2) + GFX_COMPRESSED_BUFFER_SIZE + GFX_DECOMPRESSED_BUFFER_SIZE

Library API > Display Device Driver Layer API > Advanced Display Driver Features > Microchip Graphics Controller > Set Up Display Interface > GFX_DISPLAY_BUFFER_LENGTH Macro

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