unor4matrix: add LED matrix driver for Arduino UNO R4 WiFi

examples/unor4matrix/checkerboard/main.go

@@ -0,0 +1,31 @@
+//go:build arduino_uno_r4_wifi
+
+package main
+
+import (
+	"image/color"
+
+	"tinygo.org/x/drivers/unor4matrix"
+)
+
+func main() {
+	display := unor4matrix.NewOnboard()
+	if err := display.Configure(); err != nil {
+		println(err.Error())
+		return
+	}
+	width, height := display.Size()
+	for y := int16(0); y < height; y++ {
+		for x := int16(0); x < width; x++ {
+			if (x+y)%2 == 0 {
+				display.SetPixel(x, y, color.RGBA{R: 255})
+			}
+		}
+	}
+	for {
+		if err := display.Display(); err != nil {
+			println(err.Error())
+			return
+		}
+	}
+}

examples/unor4matrix/life/life.go

@@ -0,0 +1,40 @@
+//go:build arduino_uno_r4_wifi
+
+package main
+
+const (
+	width  = 12
+	height = 8
+)
+
+type board [height][width]bool
+
+func nextGeneration(current board) (next board) {
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			neighbors := 0
+			for dy := -1; dy <= 1; dy++ {
+				for dx := -1; dx <= 1; dx++ {
+					if dx == 0 && dy == 0 {
+						continue
+					}
+					if current[(y+dy+height)%height][(x+dx+width)%width] {
+						neighbors++
+					}
+				}
+			}
+			next[y][x] = neighbors == 3 || current[y][x] && neighbors == 2
+		}
+	}
+	return next
+}
+
+func seed() board {
+	var cells board
+	cells[0][1] = true
+	cells[1][2] = true
+	cells[2][0] = true
+	cells[2][1] = true
+	cells[2][2] = true
+	return cells
+}

examples/unor4matrix/life/main.go

@@ -0,0 +1,44 @@
+//go:build arduino_uno_r4_wifi
+
+package main
+
+import (
+	"image/color"
+	"time"
+
+	"tinygo.org/x/drivers/unor4matrix"
+)
+
+const generationInterval = 300 * time.Millisecond
+
+func main() {
+	display := unor4matrix.NewOnboard()
+	if err := display.Configure(); err != nil {
+		println(err.Error())
+		return
+	}
+	cells := seed()
+	draw := func() {
+		display.ClearDisplay()
+		for y, row := range cells {
+			for x, alive := range row {
+				if alive {
+					display.SetPixel(int16(x), int16(y), color.RGBA{G: 255})
+				}
+			}
+		}
+	}
+	draw()
+	nextUpdate := time.Now().Add(generationInterval)
+	for {
+		if err := display.Display(); err != nil {
+			println(err.Error())
+			return
+		}
+		if now := time.Now(); !now.Before(nextUpdate) {
+			cells = nextGeneration(cells)
+			draw()
+			nextUpdate = now.Add(generationInterval)
+		}
+	}
+}

smoketest.sh

@@ -194,3 +194,7 @@ tinygo build -size short -o ./build/test.hex -target=wioterminal -stack-size 8kb
 # network examples (comboat)
 tinygo build -size short -o ./build/test.hex -target=elecrow-rp2040 -stack-size 8kb ./examples/net/tlsclient/
 tinygo build -size short -o ./build/test.hex -target=elecrow-rp2350 -stack-size 8kb ./examples/net/ntpclient/
+
+# Arduino UNO R4 WiFi LED matrix
+tinygo build -size short -o ./build/test.hex -target=arduino-uno-r4-wifi ./examples/unor4matrix/checkerboard/
+tinygo build -size short -o ./build/test.hex -target=arduino-uno-r4-wifi ./examples/unor4matrix/life/

unor4matrix/README.md

@@ -0,0 +1,67 @@
+# Arduino UNO R4 WiFi LED matrix
+
+Driver for the built-in 12x8 monochrome matrix. Import
+`tinygo.org/x/drivers/unor4matrix`. The driver implements `drivers.Displayer`.
+
+## Usage
+
+```go
+display := unor4matrix.NewOnboard()
+if err := display.Configure(); err != nil {
+    return
+}
+display.SetPixel(0, 0, color.RGBA{R: 255})
+for {
+    if err := display.Display(); err != nil {
+        return
+    }
+}
+```
+
+`NewOnboard` is available with `arduino_uno_r4_wifi`. `New` accepts eleven
+`CharlieplexPin` values in this order:
+
+```text
+P0_03 P0_04 P0_11 P0_12 P0_13 P0_15 P2_04 P2_05 P2_06 P2_12 P2_13
+```
+
+Set must drive the requested level. Float must initialize a high-impedance input
+without pull-ups. Configure returns `ErrMissingPinFunc` if either function is
+missing, otherwise it floats every line. Configure may be repeated and keeps
+the image. Give the device exclusive access to its pins.
+
+## Refresh model
+
+The image occupies 12 bytes. SetPixel edits it, ClearDisplay clears it, and
+LoadFrame replaces it with Arduino-format words. Words are row-major, MSB first:
+word 0 bit 31 is (0,0), word 2 bit 0 is (11,7). Any nonzero RGB is on, alpha is
+ignored, and writes outside the drawing area are ignored.
+
+Display scans all 96 slots directly from the image and floats each active pair
+after its slot. Call it repeatedly to keep an image visible. Every slot sleeps
+for 100 us, including dark pixels. A frame takes at least 9.6 ms plus GPIO and
+scheduler overhead. Before successful Configure, Display returns ErrNotConfigured.
+
+An active LED stays driven during time.Sleep. Other goroutines can prolong its on-time.
+
+## Examples and limitations
+
+```sh
+tinygo flash -target=arduino-uno-r4-wifi ./examples/unor4matrix/checkerboard
+tinygo flash -target=arduino-uno-r4-wifi ./examples/unor4matrix/life
+```
+
+Life runs a glider on a wrapping 12x8 grid with 300 ms generations. Display leaves
+the lines floating before Life computes the next generation.
+
+Use the default `tasks` scheduler. With TinyGo 0.44 and `-scheduler=none`, short
+sleeps can wait for a 1 ms SysTick, reducing refresh to about 10 Hz. Display
+blocks and foreground work pauses refresh. Call the driver from one application
+goroutine, never from an interrupt handler. Rotation and brightness control are
+unsupported. UNO R4 Minima has no built-in matrix. UNO Q uses `unoqmatrix`.
+
+## Sources
+
+- [Arduino mapping and 10 kHz timer](https://github.com/arduino/ArduinoCore-renesas/blob/424e86eff92d37f72123c2b641dd8bbf06a38b47/libraries/Arduino_LED_Matrix/src/Arduino_LED_Matrix.h).
+- [UNO R4 WiFi line order](https://github.com/arduino/ArduinoCore-renesas/blob/424e86eff92d37f72123c2b641dd8bbf06a38b47/variants/UNOWIFIR4/variant.cpp).
+- [RA4M1 hardware manual](https://www.renesas.com/en/document/mah/renesas-ra4m1-group-users-manual-hardware?language=en), R01UH0887EJ0110 Rev.1.10, sections 19.2.1, 19.2.3 and 19.2.5, pp. 357, 359 and 361-362. PODR holds the output level, POSR/PORR update it, and PDR enables output.

unor4matrix/framebuffer.go

@@ -0,0 +1,27 @@
+package unor4matrix
+
+const (
+	// Width is the number of columns in the matrix.
+	Width = 12
+	// Height is the number of rows in the matrix.
+	Height = 8
+
+	framebufferSize = (Width*Height + 7) / 8
+)
+
+type framebuffer struct{ pixels [framebufferSize]byte }
+
+func (f *framebuffer) get(index int) bool {
+	return f.pixels[index/8]&(byte(1)<<(index%8)) != 0
+}
+
+func (f *framebuffer) set(index int, on bool) {
+	mask := byte(1) << (index % 8)
+	if on {
+		f.pixels[index/8] |= mask
+	} else {
+		f.pixels[index/8] &^= mask
+	}
+}
+
+func (f *framebuffer) clear() { f.pixels = [framebufferSize]byte{} }

unor4matrix/mapping.go

@@ -0,0 +1,116 @@
+package unor4matrix
+
+// pinPair holds matrix-line indices in the line order defined by NewOnboard in matrix_unor4.go.
+type pinPair struct {
+	anode   uint8
+	cathode uint8
+}
+
+// ledMapping is row-major wiring from ArduinoCore-renesas.
+// https://github.com/arduino/ArduinoCore-renesas/blob/424e86eff92d37f72123c2b641dd8bbf06a38b47/libraries/Arduino_LED_Matrix/src/Arduino_LED_Matrix.h
+var ledMapping = [...]pinPair{
+	// Row y = 0.
+	{anode: 7, cathode: 3},
+	{anode: 3, cathode: 7},
+	{anode: 7, cathode: 4},
+	{anode: 4, cathode: 7},
+	{anode: 3, cathode: 4},
+	{anode: 4, cathode: 3},
+	{anode: 7, cathode: 8},
+	{anode: 8, cathode: 7},
+	{anode: 3, cathode: 8},
+	{anode: 8, cathode: 3},
+	{anode: 4, cathode: 8},
+	{anode: 8, cathode: 4},
+	// Row y = 1.
+	{anode: 7, cathode: 0},
+	{anode: 0, cathode: 7},
+	{anode: 3, cathode: 0},
+	{anode: 0, cathode: 3},
+	{anode: 4, cathode: 0},
+	{anode: 0, cathode: 4},
+	{anode: 8, cathode: 0},
+	{anode: 0, cathode: 8},
+	{anode: 7, cathode: 6},
+	{anode: 6, cathode: 7},
+	{anode: 3, cathode: 6},
+	{anode: 6, cathode: 3},
+	// Row y = 2.
+	{anode: 4, cathode: 6},
+	{anode: 6, cathode: 4},
+	{anode: 8, cathode: 6},
+	{anode: 6, cathode: 8},
+	{anode: 0, cathode: 6},
+	{anode: 6, cathode: 0},
+	{anode: 7, cathode: 5},
+	{anode: 5, cathode: 7},
+	{anode: 3, cathode: 5},
+	{anode: 5, cathode: 3},
+	{anode: 4, cathode: 5},
+	{anode: 5, cathode: 4},
+	// Row y = 3.
+	{anode: 8, cathode: 5},
+	{anode: 5, cathode: 8},
+	{anode: 0, cathode: 5},
+	{anode: 5, cathode: 0},
+	{anode: 6, cathode: 5},
+	{anode: 5, cathode: 6},
+	{anode: 7, cathode: 1},
+	{anode: 1, cathode: 7},
+	{anode: 3, cathode: 1},
+	{anode: 1, cathode: 3},
+	{anode: 4, cathode: 1},
+	{anode: 1, cathode: 4},
+	// Row y = 4.
+	{anode: 8, cathode: 1},
+	{anode: 1, cathode: 8},
+	{anode: 0, cathode: 1},
+	{anode: 1, cathode: 0},
+	{anode: 6, cathode: 1},
+	{anode: 1, cathode: 6},
+	{anode: 5, cathode: 1},
+	{anode: 1, cathode: 5},
+	{anode: 7, cathode: 2},
+	{anode: 2, cathode: 7},
+	{anode: 3, cathode: 2},
+	{anode: 2, cathode: 3},
+	// Row y = 5.
+	{anode: 4, cathode: 2},
+	{anode: 2, cathode: 4},
+	{anode: 8, cathode: 2},
+	{anode: 2, cathode: 8},
+	{anode: 0, cathode: 2},
+	{anode: 2, cathode: 0},
+	{anode: 6, cathode: 2},
+	{anode: 2, cathode: 6},
+	{anode: 5, cathode: 2},
+	{anode: 2, cathode: 5},
+	{anode: 1, cathode: 2},
+	{anode: 2, cathode: 1},
+	// Row y = 6.
+	{anode: 7, cathode: 10},
+	{anode: 10, cathode: 7},
+	{anode: 3, cathode: 10},
+	{anode: 10, cathode: 3},
+	{anode: 4, cathode: 10},
+	{anode: 10, cathode: 4},
+	{anode: 8, cathode: 10},
+	{anode: 10, cathode: 8},
+	{anode: 0, cathode: 10},
+	{anode: 10, cathode: 0},
+	{anode: 6, cathode: 10},
+	{anode: 10, cathode: 6},
+	// Row y = 7.
+	{anode: 5, cathode: 10},
+	{anode: 10, cathode: 5},
+	{anode: 1, cathode: 10},
+	{anode: 10, cathode: 1},
+	{anode: 2, cathode: 10},
+	{anode: 10, cathode: 2},
+	{anode: 7, cathode: 9},
+	{anode: 9, cathode: 7},
+	{anode: 3, cathode: 9},
+	{anode: 9, cathode: 3},
+	{anode: 4, cathode: 9},
+	{anode: 9, cathode: 4},
+}