Adding scroll functionality for ili9341 (#121)

* ili9341: Adding scroll functionality

Makefile

@@ -51,6 +51,8 @@ smoke-test:
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=pyportal ./examples/ili9341/basic/main.go
 	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=pyportal ./examples/ili9341/scroll/main.go
+	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=circuitplay-express ./examples/lis3dh/main.go
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=arduino-nano33 ./examples/lsm6ds3/main.go

examples/ili9341/scroll/main.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"image/color"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/ili9341"
+)
+
+var (
+	display = ili9341.NewParallel(
+		machine.LCD_DATA0,
+		machine.TFT_WR,
+		machine.TFT_DC,
+		machine.TFT_CS,
+		machine.TFT_RESET,
+		machine.TFT_RD,
+	)
+
+	red   = color.RGBA{255, 0, 0, 255}
+	blue  = color.RGBA{0, 0, 255, 255}
+	green = color.RGBA{0, 255, 0, 255}
+	black = color.RGBA{0, 0, 0, 255}
+	white = color.RGBA{255, 255, 255, 255}
+)
+
+func main() {
+
+	machine.TFT_BACKLIGHT.Configure(machine.PinConfig{machine.PinOutput})
+
+	display.Configure(ili9341.Config{})
+	width, height := display.Size()
+
+	display.FillScreen(black)
+	machine.TFT_BACKLIGHT.High()
+
+	display.FillRectangle(0, 0, width/2, height/2, white)
+	display.FillRectangle(width/2, 0, width/2, height/2, red)
+	display.FillRectangle(0, height/2, width/2, height/2, green)
+	display.FillRectangle(width/2, height/2, width/2, height/2, blue)
+	display.FillRectangle(width/4, height/4, width/2, height/2, black)
+
+	for scroll := int16(0); ; scroll = (scroll + 1) % 320 {
+		time.Sleep(7500 * time.Microsecond)
+		display.SetScroll(scroll)
+	}
+
+}

ili9341/ili9341.go

@@ -7,8 +7,6 @@ import (
 	"time"
 )
 
-const _debug = false
-
 type Config struct {
 	Width    int16
 	Height   int16
@@ -229,6 +227,26 @@ func (d *Device) SetRotation(rotation Rotation) {
 	d.rotation = rotation
 }
 
+// SetScrollWindow sets an area to scroll with fixed top and bottom parts of the display
+func (d *Device) SetScrollArea(topFixedArea, bottomFixedArea int16) {
+	d.sendCommand(VSCRDEF, []uint8{
+		uint8(topFixedArea >> 8), uint8(topFixedArea),
+		uint8(d.height - topFixedArea - bottomFixedArea>>8),
+		uint8(d.height - topFixedArea - bottomFixedArea),
+		uint8(bottomFixedArea >> 8), uint8(bottomFixedArea),
+	})
+}
+
+// SetScroll sets the vertical scroll address of the display.
+func (d *Device) SetScroll(line int16) {
+	d.sendCommand(VSCRSADD, []uint8{uint8(line >> 8), uint8(line)})
+}
+
+// SpotScroll returns the display to its normal state
+func (d *Device) StopScroll() {
+	d.sendCommand(NORON, nil)
+}
+
 // setWindow prepares the screen to be modified at a given rectangle
 func (d *Device) setWindow(x, y, w, h int16) {
 	//x += d.columnOffset