Crate ws2812_flexio
source ·Expand description
§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, therefore the recommended pixel type is LinSrgb<u8>
.
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
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:
fps = 100,000 / ((num_pixels + 1) x bytes_per_pixel + 30)
Example: For a strip with 332 SK6805 pixels, 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 board -
§Prerequisites
The following hardware is required for the examples:
- A Teensy 4.0 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 modifyrun.py
to use thepython
binary) llvm-objcopy
- Install
LLVM
tool suite
- Install
teensy-loader-cli
§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). 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.
Modules§
- Possible errors that could happen.
Structs§
- An interrupt handler that signals to the driver that an interrupt happened.
- Static memory required by the
WS2812Driver::take_interrupt_handler
function. - A buffer that preprocesses pixel data for FlexIO DMA usage.
- A WS2812 Neopixel LED Strip driver based on the i.MX RT FlexIO module
- The result of WS2812Driver::write_dma().
Traits§
- Converts an iterator of pixels into a pixel stream, usable by the driver’s
write
function. - The pins to use for WS2812.
- A pixel that can be rendered with this library.