User guide

SFSU - Embedded Systems Tutorial Nano- Electronics & Computing Research Lab
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Video Pipeline
A Scatter Gather DMA is used to connect to the VGA Controller as shown in the figure below. A
summary of how video is fed to the VGA Controller is given in the paragraph below.
The Scatter Gather DMA is used for high speed data transfer between two components. It is used to
transfer and merge noncontiguous memory to continuous address space and vice versa. It works in three
modes.
1. Memory to Memory
2. Memory to Data Stream
3. Data Stream to Memory
In this chapter, the SGDMA is used to transfer data from SDRAM to the VGA Stream. So that is option 2
from the above. A timing adapter is used to adjust the timing between the two different streams of data.
In short, it is used to connect two components that require different number of cycles to receive or send
data. A FIFO is a First In First Out queue. It is a dual clock FIFO that is used to match the system clock to
the VGA clock to normalize the flow of pixels to the VGA sink.
A RGB converter is required to convert the RGB format from BGR0 to BGR.
The VGA Controller requires 18 bit parallel RGB interface. To make the format coming from memory
(24bit RGB) compatible with the VGA sink that is connected to the tPad, we insert RGB Converter. All
these components contribute to generate a video pipeline which enables us to display a video on the tPad.
Software
The LCD screen is initialized and a blank screen can be seen. Switches are toggled to change the number
values and their operation, the result is displayed on the LCD Screen and updated every time switch is
toggled.