XPT2046 Touch driver (#350)

Co-authored-by: Steven Pearson <steven.pearson.78@gmail.com>

examples/xpt2046/main.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/xpt2046"
+)
+
+func main() {
+
+	clk := machine.GPIO0
+	cs := machine.GPIO1
+	din := machine.GPIO2
+	dout := machine.GPIO3
+	irq := machine.GPIO4
+
+	touchScreen := xpt2046.New(clk, cs, din, dout, irq)
+
+	touchScreen.Configure(&xpt2046.Config{
+		Precision: 10, //Maximum number of samples for a single ReadTouchPoint to improve accuracy.
+	})
+
+	for {
+
+		//Wait for a touch
+		for !touchScreen.Touched() {
+			time.Sleep(50 * time.Millisecond)
+		}
+
+		touch := touchScreen.ReadTouchPoint()
+		//X and Y are 16 bit with 12 bit resolution and need to be scaled for the display size
+		//Z is 24 bit and is typically > 2000 for a touch
+		println("touch:", touch.X, touch.Y, touch.Z)
+		//Example of scaling for a 240x320 display
+		println("screen:", (touch.X*240)>>16, (touch.Y*320)>>16)
+
+		//Wait for touch to end
+		for touchScreen.Touched() {
+			time.Sleep(50 * time.Millisecond)
+		}
+
+	}
+}