ws2812: add Strip type with pixel buffer and PIO support for RP2040/RP2350

Merge the neopixel package functionality into ws2812 as a new Strip type,
providing a higher-level API with pixel buffering, brightness control, and
PIO-based hardware timing on RP2040/RP2350. On other platforms, Strip falls
back to the existing bit-bang driver.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: gandarez

.claude/settings.json

@@ -0,0 +1,43 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(find /Users/gandarez/development/git/gandarez/tinygo-drivers -type f -name *ws2812*)",
+      "Bash(grep -r \"RP2350\\\\|rp2350\" /Users/gandarez/development/git/gandarez/tinygo-drivers --include=*.md --include=*.go --include=*.txt)",
+      "Bash(xargs ls:*)",
+      "Bash(grep -r \"PIO\\\\|Programmable I/O\\\\|pio\\\\|pioasm\" /Users/gandarez/development/git/gandarez/tinygo-drivers --include=*.go --include=*.md)",
+      "Read(//writeByte150/,/^func \\\\\\(d Device\\\\\\) writeByte[0-9]/**)",
+      "Bash(wc -l /Users/gandarez/development/git/gandarez/tinygo-drivers/ws2812/*.go)",
+      "Bash(tinygo version:*)",
+      "Read(//usr/local/**)",
+      "Read(//Users/gandarez/go/pkg/mod/github.com/tinygo-org/**)",
+      "Bash(find ~/go/pkg/mod/github.com/tinygo-org/tinygo@v0.37.0/src/device -name *.go)",
+      "Read(//Users/gandarez/go/pkg/mod/**)",
+      "Bash(grep -r 'type PIO' ~/go/pkg/mod/github.com/tinygo-org/tinygo@v0.37.0/src --include=*.go)",
+      "Bash(grep -r \"rp\\\\.PIO0\\\\|rp\\\\.PIO1\" ~/go/pkg/mod/github.com/tinygo-org/tinygo@v0.37.0 --include=*.go)",
+      "Bash(grep -r \"PIO0_Type\\\\|type.*PIO\" ~/go/pkg/mod/github.com/tinygo-org/tinygo@v0.37.0 --include=*.go)",
+      "Bash(find ~/go/pkg/mod/github.com/tinygo-org/tinygo@v0.37.0 -name *.svd)",
+      "Bash(find ~/go/pkg/mod/github.com/tinygo-org/tinygo@v0.37.0 -path */RP* -o -path */rp2*)",
+      "Bash(grep -i \"\\\\.go$\")",
+      "Bash(grep -r //go:generate ~/go/pkg/mod/github.com/tinygo-org/tinygo@v0.37.0/src/device --include=*.go)",
+      "Bash(find ~/go/pkg/mod/github.com/tinygo-org/tinygo@v0.37.0 -name rp*.go -o -name *rp2*.go)",
+      "Bash(grep -r PIO0_Type ~/go/pkg/mod/github.com/tinygo-org --include=*.go)",
+      "Read(//Users/gandarez/**)",
+      "Bash(PATH=\"/Users/gandarez/sdk/go1.25.0/bin:$PATH\" which tinygo)",
+      "Bash(PATH=\"/Users/gandarez/sdk/go1.25.0/bin:$PATH\" tinygo version)",
+      "Read(//opt/**)",
+      "WebFetch(domain:raw.githubusercontent.com)",
+      "Bash(gh api:*)",
+      "Bash(gh auth:*)",
+      "WebFetch(domain:github.com)",
+      "Bash(go get:*)",
+      "Bash(ls /Users/gandarez/sdk/go*/bin/go)",
+      "Bash(/Users/gandarez/sdk/go1.25.0/bin/go get:*)",
+      "Bash(/Users/gandarez/sdk/go1.25.0/bin/go mod:*)",
+      "Bash(/Users/gandarez/sdk/go1.25.0/bin/go vet:*)",
+      "Bash(git commit:*)",
+      "Bash(git push:*)",
+      "Bash(/opt/homebrew/bin/gh pr:*)",
+      "Bash(gh pr:*)"
+    ]
+  }
+}

examples/ws2812-strip/main.go

@@ -0,0 +1,36 @@
+// Demonstrates WS2812B RGB LED control using the Strip API.
+//
+// Tested on Waveshare RP2350-LCD-1.47 with onboard RGB LED on GP22.
+//
+// To flash:
+//
+//	tinygo flash -target=pico2 ./examples/ws2812-strip/
+package main
+
+import (
+	"image/color"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/ws2812"
+)
+
+func main() {
+	strip, err := ws2812.NewStrip(machine.GP22, 1)
+	if err != nil {
+		panic(err)
+	}
+	strip.SetBrightness(50)
+
+	colors := []color.RGBA{
+		{R: 255, G: 0, B: 0},
+		{R: 0, G: 255, B: 0},
+		{R: 0, G: 0, B: 255},
+	}
+
+	for i := 0; ; i = (i + 1) % 3 {
+		strip.SetPixel(0, colors[i])
+		strip.Show()
+		time.Sleep(time.Second)
+	}
+}

go.mod

@@ -1,17 +1,16 @@
 module tinygo.org/x/drivers
 
-
 go 1.22.1
 
 toolchain go1.23.1
 
-
 require (
 	github.com/eclipse/paho.mqtt.golang v1.2.0
 	github.com/frankban/quicktest v1.10.2
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510
 	github.com/orsinium-labs/tinymath v1.1.0
 	github.com/soypat/natiu-mqtt v0.5.1
+	github.com/tinygo-org/pio v0.3.0
 	golang.org/x/exp v0.0.0-20241204233417-43b7b7cde48d
 	golang.org/x/net v0.33.0
 	tinygo.org/x/tinyfont v0.3.0

go.sum

@@ -17,6 +17,8 @@ github.com/orsinium-labs/tinymath v1.1.0 h1:KomdsyLHB7vE3f1nRAJF2dyf1m/gnM2HxfTe
 github.com/orsinium-labs/tinymath v1.1.0/go.mod h1:WPXX6ei3KSXG7JfA03a+ekCYaY9SWN4I+JRl2p6ck+A=
 github.com/soypat/natiu-mqtt v0.5.1 h1:rwaDmlvjzD2+3MCOjMZc4QEkDkNwDzbct2TJbpz+TPc=
 github.com/soypat/natiu-mqtt v0.5.1/go.mod h1:xEta+cwop9izVCW7xOx2W+ct9PRMqr0gNVkvBPnQTc4=
+github.com/tinygo-org/pio v0.3.0 h1:opEnOtw58KGB4RJD3/n/Rd0/djYGX3DeJiXLI6y/yDI=
+github.com/tinygo-org/pio v0.3.0/go.mod h1:wf6c6lKZp+pQOzKKcpzchmRuhiMc27ABRuo7KVnaMFU=
 github.com/valyala/fastjson v1.6.3/go.mod h1:CLCAqky6SMuOcxStkYQvblddUtoRxhYMGLrsQns1aXY=
 golang.org/x/exp v0.0.0-20241204233417-43b7b7cde48d h1:0olWaB5pg3+oychR51GUVCEsGkeCU/2JxjBgIo4f3M0=
 golang.org/x/exp v0.0.0-20241204233417-43b7b7cde48d/go.mod h1:qj5a5QZpwLU2NLQudwIN5koi3beDhSAlJwa67PuM98c=

smoketest.sh

@@ -93,6 +93,7 @@ tinygo build -size short -o ./build/test.bin -target=m5stamp-c3          ./examp
 tinygo build -size short -o ./build/test.hex -target=feather-nrf52840 ./examples/is31fl3731/main.go
 tinygo build -size short -o ./build/test.hex -target=arduino   ./examples/ws2812
 tinygo build -size short -o ./build/test.hex -target=digispark ./examples/ws2812
+tinygo build -size short -o ./build/test.bin -target=pico2     ./examples/ws2812-strip
 tinygo build -size short -o ./build/test.hex -target=trinket-m0 ./examples/bme280/main.go
 tinygo build -size short -o ./build/test.hex -target=circuitplay-express ./examples/microphone/main.go
 tinygo build -size short -o ./build/test.hex -target=circuitplay-express ./examples/buzzer/main.go

ws2812/strip.go

@@ -0,0 +1,53 @@
+package ws2812
+
+import "image/color"
+
+// Strip controls a strip of WS2812B LEDs with a pixel buffer and brightness control.
+// Use NewStrip to create a new instance.
+type Strip struct {
+	pixels     []color.RGBA
+	brightness uint8
+	writeFunc  func(pixels []color.RGBA, brightness uint8) error
+}
+
+// SetPixel sets the color of pixel at index i.
+func (s *Strip) SetPixel(i int, c color.RGBA) {
+	if i >= 0 && i < len(s.pixels) {
+		s.pixels[i] = c
+	}
+}
+
+// Show sends the current pixel buffer to the LED strip.
+func (s *Strip) Show() error {
+	return s.writeFunc(s.pixels, s.brightness)
+}
+
+// SetBrightness sets the global brightness (0-255).
+func (s *Strip) SetBrightness(b uint8) {
+	s.brightness = b
+}
+
+// Fill sets all pixels to the given color.
+func (s *Strip) Fill(c color.RGBA) {
+	for i := range s.pixels {
+		s.pixels[i] = c
+	}
+}
+
+// Clear turns off all pixels.
+func (s *Strip) Clear() {
+	s.Fill(color.RGBA{})
+}
+
+// NumPixels returns the number of pixels in the strip.
+func (s *Strip) NumPixels() int {
+	return len(s.pixels)
+}
+
+// applyBrightness scales a color by the brightness value.
+func applyBrightness(c color.RGBA, brightness uint8) (r, g, b uint8) {
+	r = uint8((uint16(c.R) * uint16(brightness)) >> 8)
+	g = uint8((uint16(c.G) * uint16(brightness)) >> 8)
+	b = uint8((uint16(c.B) * uint16(brightness)) >> 8)
+	return
+}

ws2812/strip_other.go

@@ -0,0 +1,27 @@
+//go:build !rp2040 && !rp2350
+
+package ws2812
+
+import (
+	"image/color"
+	"machine"
+)
+
+// NewStrip creates a new WS2812B LED strip on the given pin with the specified
+// number of pixels. On platforms without PIO, it uses the bit-bang driver.
+func NewStrip(pin machine.Pin, numPixels int) (*Strip, error) {
+	pin.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	dev := NewWS2812(pin)
+	return &Strip{
+		pixels:     make([]color.RGBA, numPixels),
+		brightness: 255,
+		writeFunc: func(pixels []color.RGBA, brightness uint8) error {
+			adjusted := make([]color.RGBA, len(pixels))
+			for i, c := range pixels {
+				r, g, bl := applyBrightness(c, brightness)
+				adjusted[i] = color.RGBA{R: r, G: g, B: bl}
+			}
+			return dev.WriteColors(adjusted)
+		},
+	}, nil
+}

ws2812/strip_rp2.go

@@ -0,0 +1,35 @@
+//go:build rp2040 || rp2350
+
+package ws2812
+
+import (
+	"image/color"
+	"machine"
+
+	pio "github.com/tinygo-org/pio/rp2-pio"
+	"github.com/tinygo-org/pio/rp2-pio/piolib"
+)
+
+// NewStrip creates a new WS2812B LED strip on the given pin with the specified
+// number of pixels. On RP2040/RP2350, it uses PIO for hardware-timed control.
+func NewStrip(pin machine.Pin, numPixels int) (*Strip, error) {
+	sm, err := pio.PIO0.ClaimStateMachine()
+	if err != nil {
+		return nil, err
+	}
+	ws, err := piolib.NewWS2812B(sm, pin)
+	if err != nil {
+		return nil, err
+	}
+	return &Strip{
+		pixels:     make([]color.RGBA, numPixels),
+		brightness: 255,
+		writeFunc: func(pixels []color.RGBA, brightness uint8) error {
+			for _, c := range pixels {
+				r, g, bl := applyBrightness(c, brightness)
+				ws.PutRGB(r, g, bl)
+			}
+			return nil
+		},
+	}, nil
+}

ws2812/ws2812.go

@@ -1,4 +1,9 @@
 // Package ws2812 implements a driver for WS2812 and SK6812 RGB LED strips.
+//
+// For low-level control, use Device with NewWS2812 or NewSK6812.
+// For a higher-level API with pixel buffering and brightness control,
+// use Strip with NewStrip. On RP2040/RP2350, Strip uses PIO for
+// hardware-timed control; on other platforms it falls back to bit-banging.
 package ws2812 // import "tinygo.org/x/drivers/ws2812"
 
 //go:generate go run gen-ws2812.go -arch=cortexm 16 48 64 120 125 150 168 200