FPGA Register Space

p

LED Sign

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Processor Memory Map

Address	Function
0x10000: 0x2ffff	Display Memory, Addressable as byte, word and longword
0x30000: 0x3007C	Register Space
0x50000: 0x50180	Character memory
0x58000: 0x58400	Character Font memory Font: 8 bytes per character; first byte is top 8 pixels of character, last byte is bottom 8 pixels

FPGA Register Space

Address	Register Name	Function
0x30000	Virt_Scrn_Width	Number of longwords in one horizonal scan line. Normally set to 0x30 for 192 byte screen width. This register can be used to create a virtual screen over which the actual display screen may be panned.
0x30004	Scrn_Origin	Address of first longword in screen memory where the display page should start reading. First longword is upper left corner of display. Changing the value in this register allows the display screen to pan through the virtual screen.
0x30008	Backgrnd_Color	Byte wide register containing the display background color when the background color is enabled.
0x3000C	Display_Mode	This register enables/disables graphics/text operation. The register also contains bits to control how the text and graphics data are mixed (AND, OR, XOR) Background color enable is in this register, as well.
0x30010	Draw_Color	The point engine, line engine and polygon filler write the byte-wide color value contained in this register into display memory when the engines are running.
0x30014	Draw_Command	This register is used to enable the line, point, polygon and rotation modules. Bits in this register also select the axis of rotation used by the rotator module
0x30018	XA	X1 coordinate. This register is written with the X coordinate for the point engine, the starting X coordinate for the line engine and one of three X values for the polygon filler.
0x3001C	YA	Y1 coordinate. This register is written with the Y coordinate for the point engine, the starting Y coordinate for the line engine and one of three Y values for the polygon filler.
0x30020	XB	X2 coordinate. This register is written with the ending X coordinate for the line engine or one of three X values for the polygon filler.
0x30024	YB	Y2 coordinate. This register is written with the ending Y coordinate for the line engine or one of three Y values for the polygon filler.
0x30028	XC	X3 coordinate. This register is written with one of three X values for the polygon filler.
0x3002C	YC	Y3 coordinate. This register is written with one of three Y values for the polygon filler.
0x30030	XD	X4 coordinate. No function defined. This register is available for storage
0x30034	YD	Y4 coordinate. No function defined. This register is available for storage.
0x30038	Eng_Stat	This register is used by the line engine, polygon filler and rotation module to indicate to the processor when the engines are busy. (One bit per engine; point engine doesn’t have a busy bit.. the engine finishes before the CPU can possibly load the next coordinate pair.)
0x3003C	Char_Color	Byte-wide color value assigned to characters when character mode is enabled.
0x30040	Blink_freq	Nibble-wide blink frequency used to blink characters. Resolution: 1/16 second
0x30044	Xdelta	Reserved (Line engine register, non-writable)
0x30048	Ydelta	Reserved (Line engine register, non-writable)
0x3004C	Yincb	Reserved (Line engine register, non-writable)
0x30050	Clip_X_top	X coordinate of upper left point of clipping rectangle
0x30054	Clip_Y_top	Y coordinate of upper left point of clipping rectangle
0x30058	Clip_X_bottom	X coordinate of lower right point of clipping rectangle
0x3005C	Clip_Y_bottom	Y coordinate of lower right point of clipping rectangle
0x30060	Vertex_X	X coordinate of vertex to be rotated (24-bit fixed point format)
0x30064	Vertex_Y	Y coordinate of vertex to be rotated (24-bit fixed point format)
0x30068	Vertex_Z	Z coordinate of vertex to be rotated (24-bit fixed point format)
0x3006C	Vertex_X_Prime	Rotated X coordinate. This register written by rotator module after rotation completes.
0x30070	Vertex_Y_Prime	Rotated Y coordinate. This register written by rotator module after rotation completes.
0x30074	Vertex_Z_Prime	Rotated Z coordinate. This register written by rotator module after rotation completes.
0x30078	Theta	Angle of rotation for rotator module (9-bit value: 360 degrees/512)

Register Encoding

Background Color
Bit(s)	Function
7:4	Green Intensity
3:0	Red Intensity

Display Mode
Bit(s)	Function
0	Enable Background Color when high
1	Text Only when high
2	Graphics Only when high
3	Text/Graphics pixels OR together
4	Text/Graphics pixels AND together
5	Enable Text page blink
6	Text/Graphics pixels XOR together
7	Invert Character color

Point/Line/Polygon/Rotation Engine Enable
Bit(s)	Function
2:0	001 => Start Point Engine 010 => Start Line Engine 011 => Start Polygon Filler 100 => Start Rotation Engine
7:3	Reserved
9:8	00 => Rotate about Z axis 01 => Rotate about X axis 10 => Rotate about Y axis

Engine Status
Bit(s)	Function
0	Line Engine busy when high
1	Rotation Engine busy when high
2	Polygon Filler busy when high

If you have any questions about the sign feel free to email me

Register definitions as of 6/20/03

Email: rhirsch81@comcast.net