teletext.h File Reference

Data Structures
struct	t_teletext_timings
struct	t_teletext_character
struct	t_teletext_rom_access
struct	t_teletext_pixels

Enumerations
enum	t_teletext_vertical_interpolation {   tvi_all_scanlines,   tvi_even_scanlines,   tvi_odd_scanlines }

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Data Structure Documentation

struct t_teletext_timings

Data Fields
bit	end_of_scanline	Asserted if end of scanline
bit	first_scanline_of_row	Asserted if first scanline of row; not required if module's internal timing is trusted
t_teletext_vertical_interpolation	interpolate_vertical	Asserted if vertical interpolation is desired
bit	restart_frame	Asserted if restarting the frame (resets all teletext character state)
bit	smoothe	Asserted if interpolation is desired

struct t_teletext_character

Data Fields
bit[7]	character
bit	valid

struct t_teletext_rom_access

Data Fields
bit[7]	address
bit	select

struct t_teletext_pixels

Data Fields
bit[12]	blue
bit[12]	green
bit	last_scanline	Asserted with a pixel to indicate it is on the last scanline of the row
bit[12]	red
bit	valid	Asserted to indicate that the red, green and blue are valid; asserted three ticks after a valid character in

Enumeration Type Documentation

enum t_teletext_vertical_interpolation

Enumerator
tvi_all_scanlines	For twenty scanline output characters
tvi_even_scanlines	Only output scanlines 0, 2, 4, ... 18 - for even interlace fields, or for 10-scanline displays
tvi_odd_scanlines	For twenty scanline output characters, but only outputing scanlines 1, 3, 5, ... 19 - for odd interlace fields

Modules

module teletext	(	clock	clk,
		input bit	reset_n,
		input t_teletext_character	character,
		input t_teletext_timings	timings,
		output t_teletext_rom_access	rom_access,
		input bit	rom_data[45],
		output t_teletext_pixels	pixels
	)

Parameters

[in]	clk	Character clock
[in]	character	Parallel character data in, with valid signal
[in]	timings	Timings for the scanline, row, etc
[out]	rom_access	Teletext ROM access
[in]	rom_data	Teletext ROM data, valid in cycle after rom_access
[out]	pixels	Output pixels, two clock ticks delayed from clk in