esp32: provide hardware pin constants

src/machine/machine_esp32.go

@@ -31,6 +31,44 @@ const (
 	PinInputPulldown
 )
 
+// Hardware pin numbers
+const (
+	GPIO0  Pin = 0
+	GPIO1  Pin = 1
+	GPIO2  Pin = 2
+	GPIO3  Pin = 3
+	GPIO4  Pin = 4
+	GPIO5  Pin = 5
+	GPIO6  Pin = 6
+	GPIO7  Pin = 7
+	GPIO8  Pin = 8
+	GPIO9  Pin = 9
+	GPIO10 Pin = 10
+	GPIO11 Pin = 11
+	GPIO12 Pin = 12
+	GPIO13 Pin = 13
+	GPIO14 Pin = 14
+	GPIO15 Pin = 15
+	GPIO16 Pin = 16
+	GPIO17 Pin = 17
+	GPIO18 Pin = 18
+	GPIO19 Pin = 19
+	GPIO21 Pin = 21
+	GPIO22 Pin = 22
+	GPIO23 Pin = 23
+	GPIO25 Pin = 25
+	GPIO26 Pin = 26
+	GPIO27 Pin = 27
+	GPIO32 Pin = 32
+	GPIO33 Pin = 33
+	GPIO34 Pin = 34
+	GPIO35 Pin = 35
+	GPIO36 Pin = 36
+	GPIO37 Pin = 37
+	GPIO38 Pin = 38
+	GPIO39 Pin = 39
+)
+
 // Configure this pin with the given configuration.
 func (p Pin) Configure(config PinConfig) {
 	// Output function 256 is a special value reserved for use as a regular GPIO