Datasheet

Jon Waddington
19
3.2.1 TV Cirtcuit
Each cog of the Propeller has an integrated video generator that makes generating video
signals possible. Access and control of the video generator are provided by two registers ,
the Video Scale register and the Video Configuration register. The value in the Video
Scale register determines the number of clock cycles before the next frame of data is
fetched and it also indicates the number of clock cycles there are for each pixel. The
Video Configuration register specifies the settings for the video signal. For example
whether it is VGA or composite and what pins to output the signal on. [18]
The circuit in figure 3.2.1 shows how the chroma and luminance is combined to generate
the 75Ω, 1V, baseband video signal. [18]
The Propeller Object Exchange provided an object specifically intended to generate PAL
video signals. This object was used to generate the video for the Information System.
Figure 3.2.1. Schematic of the TV Circuit