Added Gopher ARCADE board

src/machine/board_gopher-arcade.go

@@ -0,0 +1,22 @@
+//go:build gopher_arcade
+
+package machine
+
+// Return the current CPU frequency in hertz.
+func CPUFrequency() uint32 {
+	return 8000000
+}
+
+const (
+	P5 Pin = PB0
+	P6 Pin = PB1
+	P7 Pin = PB2
+	P2 Pin = PB3
+	P3 Pin = PB4
+	P1 Pin = PB5
+
+	LED          = P1
+	BUTTON_LEFT  = P7
+	BUTTON_RIGHT = P5
+	SPEAKER      = P6
+)