ssd1306: improvements needed for Thumby SPI display

Signed-off-by: deadprogram <ron@hybridgroup.com>

examples/ssd1306/spi_thumby/main.go

@@ -0,0 +1,50 @@
+// This example using the SSD1306 OLED display over SPI on the Thumby board
+// A very tiny 72x40 display.
+package main
+
+import (
+	"image/color"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/ssd1306"
+)
+
+func main() {
+	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},
+	})
+
+	display.ClearDisplay()
+
+	x := int16(36)
+	y := int16(20)
+	deltaX := int16(1)
+	deltaY := int16(1)
+	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 == 71 {
+			deltaX = -deltaX
+		}
+
+		if y == 0 || y == 39 {
+			deltaY = -deltaY
+		}
+		time.Sleep(1 * time.Millisecond)
+	}
+}