https://github.com/finomnis/ws2812-flexio

A neopixel driver for Rust, based on NXP i.MX RT's FlexIO bus.
https://github.com/finomnis/ws2812-flexio

embedded-rust imxrt neopixel

Last synced: 11 days ago
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A neopixel driver for Rust, based on NXP i.MX RT's FlexIO bus.

• Host: GitHub
• URL: https://github.com/finomnis/ws2812-flexio
• Owner: Finomnis
• License: apache-2.0
• Created: 2023-06-08T12:21:24.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2024-06-29T08:24:48.000Z (4 months ago)
• Last Synced: 2024-10-09T07:13:10.370Z (29 days ago)
• Topics: embedded-rust, imxrt, neopixel
• Language: Rust
• Homepage:
• Size: 125 KB
• Stars: 4
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE-APACHE.txt

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README

        
# ws2812-flexio

[![Crates.io](https://img.shields.io/crates/v/ws2812-flexio)](https://crates.io/crates/ws2812-flexio)

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[![docs.rs](https://img.shields.io/docsrs/ws2812-flexio)](https://docs.rs/ws2812-flexio)

A neopixel driver based on NXP i.MX RT's FlexIO bus.

## Pixel Type

The default color space of NeoPixel LED strips is 8-bit [linear sRGB](https://matt77hias.github.io/blog/2018/07/01/linear-gamma-and-sRGB-color-spaces.html), therefore the recommended pixel type is [`LinSrgb`](https://docs.rs/palette/latest/palette/type.LinSrgb.html).

Be aware that this differs from normal, gamma corrected sRGB; a conversion has to take place.

More info can be found in the documentation of the [`palette`](https://docs.rs/palette) crate.

## Operating Modes

This crate can operate either in blocking mode or in DMA driven asynchronous mode.

## Specs

### Parallel strips

  The library can drive multiple strips in parallel. To be more specific, driving multiple strips from the same FlexIO instance requires `2 + 2 * strips` FlexIO timers, so a for example a FlexIO instance with `8` timers can drive `3` strips in parallel.

### Framerate

  The library drives the LED strips at 800kHz with a latch time of 300us. This gives us the following formula:

  ```python

  fps = 100,000 / ((num_pixels + 1) x bytes_per_pixel + 30)

  ```

  Example: For a strip with [332 SK6805 pixels](https://www.ipixelleds.com/index.php?id=923), we can achieve `100,000 / ((332 + 1) * 3 + 30) = 97.18` fps.

  Be aware that this framerate is only realistic for DMA based writes; with blocking writes, additional time gets lost while the next frame gets computed.

# Examples

*- examples are intended for the [Teensy 4.0](https://www.pjrc.com/store/teensy40.html) board -*

## Prerequisites

The following hardware is required for the examples:

- A [Teensy 4.0](https://www.pjrc.com/store/teensy40.html) development board

- A way to read the Teensy's UART, like a USB-UART-converter

The following software tools have to be installed:

- Python3 (as `python3`, or modify `run.py` to use the `python` binary)

- `llvm-objcopy`

  - Install [`LLVM`](https://github.com/llvm/llvm-project/releases) tool suite

- [`teensy-loader-cli`](https://www.pjrc.com/teensy/loader_cli.html)

## Run

- Connect the Teensy to PC via USB cable.

- Run `cargo run --release --example triple_332`.

- Read the output of the examples on the Teensy's UART.

- Pin 6, 7 and 8 output data for NeoPixel RGB strips of length 332 each

  (for example [P/N: S010332ZA3SA8](https://www.ipixelleds.com/index.php?id=923)).

  Note that those pins output 3.3V, and most NeoPixel LED strips require a 5V data signal, which means an external level shifter is required.