PICO PIO testing with WS2812B

[Gustavomurta]

Congratulations Patricio! I've already managed to do some tests on the Raspberry Pico with the WS281B example. Thank you.
https://github.com/tinygo-org/pio/tree/main/rp2-pio/examples/ws2812

But I found some things that need correction or change.

ws, err := piolib.NewWS2812(sm, ws2812Pin, 16000000)

This function lacked the definition of the Baud rate.
Through testing, I discovered the frequency of 16MHz (maybe it is based on Arduino?).
func NewWS2812(sm pio.StateMachine, pin machine.Pin, baud uint32) (*WS2812, error)

The color sequence appears to be incorrect.
Based on the WS2812B datasheet, we can verify that the color sequence in the 24 bits is green-red-blue and not RGB.
https://cdn-shop.adafruit.com/datasheets/WS2812.pdf

https://github.com/tinygo-org/pio/blob/main/rp2-pio/piolib/ws2812.go

func (ws *WS2812) SetRGB(r, g, b uint8) {
	color := uint32(r)<<16 | uint32(g)<<8 | uint32(b)
	println("r", r, "g", g, "b", b)
	ws.sm.TxPut(color)
}

[Gustavomurta]

If you find it convenient to make changes to faithfully adapt the bit time specifications (+- 150ns):

WS2812B:

T0H = 400ns / T0L = 850ns
T1H = 800ns / T1L = 450ns

My measurements with logic analyzer:

T0H = 500ns / T0L = 458 ns (can improve)

T1H = 875ns / T1L = 417ns (very good)

[soypat]

I've reverted the changes and moved all changes to a PR for better following of changes.

[Gustavomurta]

Thank you Patrício!

[soypat]

Latest main now contains changes that match the tinygo drivers implementation behaviour, please give it a try!