# Tiny Tapeout 5: WS2812B LED strip driver
This project drives a strip of WS2812B RGB LEDs, periodically updating the strip with random color values. The project consists of three main modules:
- a [linear feedback 16-bit shift register](https://en.wikipedia.org/wiki/Linear-feedback_shift_register) to generate a stream of pseudo-random bits
- a 5-bit synchronous increasing counter, wrapping to 0 when the counter reaches 25. WHen driven by a 20 MHz clock source, the counter generates the 1.25 us pulses required by the [WS2812B protocol](https://cdn-shop.adafruit.com/datasheets/WS2812B.pdf). The duration of the high phase of the pulse is controlled by the random bit stream generated above.
- a 16-bit ripple counter increasing at the end of each pulse, used to divide the pulse frequency and generate the LED strip refresh signal
The RST_N signal resets the state of the pulse generator and holds low the line driving the LED strip (LED strip refresh).
| Input | Description |
|---------|-----------------|
| 0 | clock source selection |
| 1 | external clock source |
| 2 | refresh freq sel (low) |
| 3 | refresh freq sel (high) |
| 4 | N/A |
| 5 | N/A |
| 6 | WS2812B LED strip output |
| 7 | shift register input |
| Output | Description |
|---------|-----------------|
| 0 | shift register output |
| 1 | shift register clock |
| 2 | WS2812B LED strip input |
| 3 | LED strip overflow |
| 4 | LED strip refresh |
| 5 | N/A |
| 6 | N/A |
| 7 | N/A |
ERC Warnings
flop10:CLK: Clock driven by combinatorial logic
flop11:CLK: Clock driven by combinatorial logic
flop12:CLK: Clock driven by combinatorial logic
flop13:CLK: Clock driven by combinatorial logic
flop14:CLK: Clock driven by combinatorial logic
flop15:CLK: Clock driven by combinatorial logic
flop16:CLK: Clock driven by combinatorial logic
flop1:CLK: Clock driven by combinatorial logic
flop24:CLK: Clock driven by combinatorial logic
flop2:CLK: Clock driven by combinatorial logic
15 additional warning(s) hidden