ssd1306: avoid unnecessary heap allocations (#767)

* ssd1306: avoid unnecessary heap allocations

* ssd1306: extract i2c and spi bus implementations

* ssd1306: refactor tests -- show fps and heap usage

* ssd1306: bring back the lost exported methods

* Adjust examples

* Fix smoketests for ssd1306

Author: ysoldak

examples/ssd1306/i2c_128x32/main.go

@@ -0,0 +1,59 @@
+package main
+
+// This example shows how to use SSD1306 OLED display driver over I2C and SPI.
+//
+// Check the `newSSD1306Display()` functions for I2C and SPI initializations.
+
+import (
+	"runtime"
+
+	"image/color"
+	"time"
+)
+
+func main() {
+
+	display := newSSD1306Display()
+	display.ClearDisplay()
+
+	w, h := display.Size()
+	x := int16(0)
+	y := int16(0)
+	deltaX := int16(1)
+	deltaY := int16(1)
+
+	traceTime := time.Now().UnixMilli() + 1000
+	frames := 0
+	ms := runtime.MemStats{}
+
+	for {
+		pixel := display.GetPixel(x, y)
+		c := color.RGBA{255, 255, 255, 255}
+		if pixel {
+			c = color.RGBA{0, 0, 0, 255}
+		}
+		display.SetPixel(x, y, c)
+		display.Display()
+
+		x += deltaX
+		y += deltaY
+
+		if x == 0 || x == w-1 {
+			deltaX = -deltaX
+		}
+
+		if y == 0 || y == h-1 {
+			deltaY = -deltaY
+		}
+
+		frames++
+		now := time.Now().UnixMilli()
+		if now >= traceTime {
+			runtime.ReadMemStats(&ms)
+			println("TS", now, "| FPS", frames, "| HeapInuse", ms.HeapInuse)
+			traceTime = now + 1000
+			frames = 0
+		}
+	}
+
+}

examples/ssd1306/i2c_128x64/main.go

@@ -0,0 +1,38 @@
+//go:build xiao_ble
+
+// This initializes SSD1306 OLED display driver over I2C.
+//
+// Seeed XIAO BLE board + SSD1306 128x32 I2C OLED display.
+//
+// Wiring:
+// - XIAO GND      -> OLED GND
+// - XIAO 3v3      -> OLED VCC
+// - XIAO D4 (SDA) -> OLED SDA
+// - XIAO D5 (SCL) -> OLED SCK
+//
+// For your case:
+// - Connect the display to I2C pins on your board.
+// - Adjust I2C address and display size as needed.
+
+package main
+
+import (
+	"machine"
+
+	"tinygo.org/x/drivers/ssd1306"
+)
+
+func newSSD1306Display() *ssd1306.Device {
+	machine.I2C0.Configure(machine.I2CConfig{
+		Frequency: 400 * machine.KHz,
+		SDA:       machine.SDA0_PIN,
+		SCL:       machine.SCL0_PIN,
+	})
+	display := ssd1306.NewI2C(machine.I2C0)
+	display.Configure(ssd1306.Config{
+		Address: ssd1306.Address_128_32, // or ssd1306.Address
+		Width:   128,
+		Height:  32, // or 64
+	})
+	return display
+}

examples/ssd1306/main.go

@@ -0,0 +1,27 @@
+//go:build thumby
+
+// This initializes SSD1306 OLED display driver over SPI.
+//
+// Thumby board has a tiny built-in 72x40 display.
+//
+// As the display is built-in, no wiring is needed.
+
+package main
+
+import (
+	"machine"
+
+	"tinygo.org/x/drivers/ssd1306"
+)
+
+func newSSD1306Display() *ssd1306.Device {
+	machine.SPI0.Configure(machine.SPIConfig{})
+	display := ssd1306.NewSPI(machine.SPI0, machine.THUMBY_DC_PIN, machine.THUMBY_RESET_PIN, machine.THUMBY_CS_PIN)
+	display.Configure(ssd1306.Config{
+		Width:     72,
+		Height:    40,
+		ResetCol:  ssd1306.ResetValue{28, 99},
+		ResetPage: ssd1306.ResetValue{0, 5},
+	})
+	return display
+}

examples/ssd1306/main_i2c_xiao-ble.go

@@ -0,0 +1,40 @@
+//go:build xiao_rp2040
+
+// This initializes SSD1306 OLED display driver over SPI.
+//
+// Seeed XIAO RP2040 board + SSD1306 128x64 SPI OLED display.
+//
+// Wiring:
+// - XIAO GND       -> OLED GND
+// - XIAO 3v3       -> OLED VCC
+// - XIAO D8 (SCK)  -> OLED D0
+// - XIAO D10 (SDO) -> OLED D1
+// - XIAO D4        -> OLED RES
+// - XIAO D5        -> OLED DC
+// - XIAO D6        -> OLED CS
+//
+// For your case:
+// - Connect the display to SPI pins on your board.
+// - Adjust RES, DC and CS pins as needed.
+// - Adjust SPI frequency as needed.
+// - Adjust display size as needed.
+
+package main
+
+import (
+	"machine"
+
+	"tinygo.org/x/drivers/ssd1306"
+)
+
+func newSSD1306Display() *ssd1306.Device {
+	machine.SPI0.Configure(machine.SPIConfig{
+		Frequency: 50 * machine.MHz,
+	})
+	display := ssd1306.NewSPI(machine.SPI0, machine.D5, machine.D4, machine.D6)
+	display.Configure(ssd1306.Config{
+		Width:  128,
+		Height: 64,
+	})
+	return display
+}

examples/ssd1306/main_spi_thumby.go

@@ -65,8 +65,9 @@ tinygo build -size short -o ./build/test.hex -target=pybadge ./examples/shifter/
 tinygo build -size short -o ./build/test.hex -target=microbit ./examples/sht3x/main.go
 tinygo build -size short -o ./build/test.hex -target=microbit ./examples/sht4x/main.go
 tinygo build -size short -o ./build/test.hex -target=microbit ./examples/shtc3/main.go
-tinygo build -size short -o ./build/test.hex -target=microbit ./examples/ssd1306/i2c_128x32/main.go
-tinygo build -size short -o ./build/test.hex -target=microbit ./examples/ssd1306/spi_128x64/main.go
+tinygo build -size short -o ./build/test.hex -target=xiao-ble ./examples/ssd1306/
+tinygo build -size short -o ./build/test.hex -target=xiao-rp2040 ./examples/ssd1306/
+tinygo build -size short -o ./build/test.hex -target=thumby ./examples/ssd1306/
 tinygo build -size short -o ./build/test.hex -target=microbit ./examples/ssd1331/main.go
 tinygo build -size short -o ./build/test.hex -target=microbit ./examples/st7735/main.go
 tinygo build -size short -o ./build/test.hex -target=microbit ./examples/st7789/main.go