714 Self-Seeding Adaptive 16-bit Galois LFSR PRNG
714 : Self-Seeding Adaptive 16-bit Galois LFSR PRNG
- Author: Preethi S A, Khushi Vishwanath, Shylashree N, RV College Of Engineering
- Description: A compact 16-bit Galois LFSR PRNG with deterministic self-seeding, automatic polynomial switching, repetition detection, and cooldown control.
- GitHub repository
- Open in 3D viewer
- Open in Tiny Tapeout Explorer
- Clock: 50000000 Hz
Credits
We gratefully acknowledge the Center of Excellence (CoE) in Integrated Circuits and Systems (ICAS) and the Department of Electronics and Communication Engineering (ECE) for providing the necessary resources and guidance.
Special thanks to Dr. H V Ravish Aradhya (HoD- ECE), Dr. K R Usha Rani (Associate Dean-PG), Dr. K. S. Geetha (Vice Principal) and Dr. K. N. Subramanya (Principal) for their constant encouragement and support in facilitating this Tiny Tapeout SKY26C submission.
Self-Seeding Adaptive 16-bit Galois LFSR PRNG
How it works
This project implements a compact 16-bit Galois Linear Feedback Shift Register (LFSR) based pseudo-random number generator.
The design uses three internally selectable polynomial configurations. It starts with polynomial P0 and generates an 8-bit pseudo-random output from the lower 8 bits of the 16-bit LFSR state.
The PRNG includes deterministic self-seeding using an external 7-bit seed input. The generated 16-bit seed is protected against the all-zero state.
An 8-bit repetition monitor observes consecutive PRNG outputs. When a repetition event is detected, the adaptive controller switches the polynomial in the sequence:
P0 → P1 → P2 → P0
At the same time, the controller generates a deterministic new seed from the current LFSR state. A 3-cycle cooldown period prevents immediate repeated adaptive events after polynomial switching and reseeding.
The main blocks are:
- 16-bit Galois LFSR
- Deterministic seed generator
- 8-bit repetition monitor
- Adaptive polynomial controller
- Cooldown control
- 8-bit pseudo-random output
The PRNG is enabled using ui_in[7]. The external seed is supplied through ui_in[6:0].
How to test
- Apply reset by driving
rst_nlow. - Release reset by driving
rst_nhigh. - Set
enahigh. - Provide a non-zero 7-bit seed through
ui_in[6:0]. - Set
ui_in[7]high to enable the PRNG. - Observe the pseudo-random sequence on
uo_out[7:0]. - Verify that successive outputs are generated from the 16-bit LFSR state.
- Continue the simulation for multiple clock cycles and verify that the output does not remain constant.
- Monitor the polynomial status and adaptive event internally during simulation if required.
- Verify that an adaptive event causes polynomial switching and deterministic reseeding.
- Verify that the cooldown period prevents immediate subsequent adaptive events.
The Cocotb testbench in test/test.py performs the basic functional verification of the PRNG, including reset, seeding, LFSR operation, output generation, and re-enabling behavior.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | Seed bit 0 | Random output bit 0 | |
| 1 | Seed bit 1 | Random output bit 1 | |
| 2 | Seed bit 2 | Random output bit 2 | |
| 3 | Seed bit 3 | Random output bit 3 | |
| 4 | Seed bit 4 | Random output bit 4 | |
| 5 | Seed bit 5 | Random output bit 5 | |
| 6 | Seed bit 6 | Random output bit 6 | |
| 7 | PRNG enable | Random output bit 7 |