frisnit/fpga-noise

FPGA implementation of a LFSR noise generator with VGA output

fpga-noise

An FPGA implementation of a LFSR noise generator with VGA output for the Elbert V2 FPGA demo board

This implements a 32-bit linear feedback shift register noise generator to produce a 'TV static'-like effect on a VGA monitor.

The VGA output is 640x480 60Hz with a pixel clock of 25MHz. The LFSR is clocked at 192MHz, 8 times the pixel clock, in order to generate the 8bpp 'colour' noise effect.

The 32-bit LFSR has a period of 2^32 bits (4294967296) which repeats about every 22 seconds at 192MHz.

DIP switch 1 'pauses' the noise display:

This reloads the LFSR seed value on each VSYNC causing the same random sequence to be produced each frame.

DIP switch 2 switches between colour/monochrome noise output:

Monochrome noise

Colour noise

DIP switch 3 switches between noise mode and test mode:

Monochrome test

Colour test

This was built around the Elbert V2 demo code, the 7-segment LED driver is still used to give some feedback from the DIP switches.