For usage with the smart-leds crate.
An embedded-hal driver for ws2812 leds using spi as the timing provider.
It provides two variants: - The normal usage
Your spi peripheral has to run at 3MHz & the SPI data is created on-the-fly. This means that your core has to be reasonably fast (~48 MHz). - Prerendered
If your core is too slow or your SPI peripheral has a different frequency, you may want to use this. It creates all the data beforehand & then sends it. This means that you have to provide a data array that's large enough for all the spi data.
If the first led is always on, no matter what data you put in, your spi is probably not setting the mosi line to low on idle (You can check with a multimeter). It may also be a timing issue with the first bit being sent, this is the case on the stm32f030 with 2MHz (although using it with 2MHz is really not recommended).
You could try using the mosi_idle_high feature, it might help.
Is your device fast enough? Is your iterator fast enough? Taking too long may completly screw up the timings for the normal version. Try the prerendered variant.
Is everything white? This may stem from an spi peripheral that's too slow or one that takes too much time in-between bytes
When opening an issue about wrong/strange data, it would help if you include your code (of course) and a capture of MOSI & SCK from an oscilloscop/a logic analyzer.
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