atmel-samd & esp8266: Make sure pins are not already in use.

This prevents corrupting previous functional objects by stealing their pins
out from under them. It prevents this by ensuring that pins are in default
state before claiming them. It also verifies pins are released correctly and
reset on soft reset.

Fixes #4, instantiating a second class will fail.
Fixes #29, pins are now reset too.

1 files changed, 6 insertions, 0 deletions

diff --git a/shared-bindings/microcontroller/Pin.c b/shared-bindings/microcontroller/Pin.c
index c691a9a17..d564d6d10 100644
--- a/shared-bindings/microcontroller/Pin.c
+++ b/shared-bindings/microcontroller/Pin.c
@@ -53,3 +53,9 @@ void assert_pin(mp_obj_t obj, bool none_ok) {
         nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "Expected a Pin"));
     }
 }
+
+void assert_pin_free(const mcu_pin_obj_t* pin) {
+    if (pin != NULL && !common_hal_mcu_pin_is_free(pin)) {
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "Pin %q in use", pin->name));
+    }
+}