4 files changed, 19 insertions, 7 deletions
diff --git a/esp8266/common-hal/microcontroller/Pin.c b/esp8266/common-hal/microcontroller/Pin.c
index 23524e2ca..d20a6a997 100644
--- a/esp8266/common-hal/microcontroller/Pin.c
+++ b/esp8266/common-hal/microcontroller/Pin.c
@@ -25,6 +25,7 @@
  */
 
 #include "common-hal/microcontroller/__init__.h"
+#include "common-hal/microcontroller/Pin.h"
 #include "shared-bindings/microcontroller/Pin.h"
 
 #include "eagle_soc.h"
@@ -32,11 +33,16 @@
 extern volatile bool adc_in_use;
 
 bool common_hal_mcu_pin_is_free(const mcu_pin_obj_t* pin) {
-    return (pin == &pin_TOUT && adc_in_use) ||
-            ((READ_PERI_REG(pin->peripheral) &
+    if (pin == &pin_TOUT) {
+        return !adc_in_use;
+    }
+    if (pin->gpio_number == NO_GPIO || pin->gpio_number == SPECIAL_CASE) {
+        return false;
+    }
+    return (READ_PERI_REG(pin->peripheral) &
                 (PERIPHS_IO_MUX_FUNC<<PERIPHS_IO_MUX_FUNC_S)) == 0 &&
              (GPIO_REG_READ(GPIO_ENABLE_ADDRESS) & (1 << pin->gpio_number)) == 0 &&
-             (READ_PERI_REG(pin->peripheral) & PERIPHS_IO_MUX_PULLUP) == 0 );
+             (READ_PERI_REG(pin->peripheral) & PERIPHS_IO_MUX_PULLUP) == 0;
 }
 
 void reset_pins(void) {
diff --git a/esp8266/common-hal/microcontroller/Pin.h b/esp8266/common-hal/microcontroller/Pin.h
index 428ece1c2..a06e9c195 100644
--- a/esp8266/common-hal/microcontroller/Pin.h
+++ b/esp8266/common-hal/microcontroller/Pin.h
@@ -27,6 +27,10 @@
 #ifndef __MICROPY_INCLUDED_ESP8266_COMMON_HAL_MICROCONTROLLER_PIN_H__
 #define __MICROPY_INCLUDED_ESP8266_COMMON_HAL_MICROCONTROLLER_PIN_H__
 
+// Magic values for gpio_number.
+#define NO_GPIO 0xff
+#define SPECIAL_CASE 0xfe
+
 void reset_pins(void);
 
 #endif  // __MICROPY_INCLUDED_ESP8266_COMMON_HAL_MICROCONTROLLER_PIN_H__
diff --git a/esp8266/common-hal/microcontroller/__init__.c b/esp8266/common-hal/microcontroller/__init__.c
index deb7a6182..f14143e7d 100644
--- a/esp8266/common-hal/microcontroller/__init__.c
+++ b/esp8266/common-hal/microcontroller/__init__.c
@@ -24,6 +24,7 @@
  * THE SOFTWARE.
  */
 
+#include "common-hal/microcontroller/Pin.h"
 #include "common-hal/microcontroller/types.h"
 #include "shared-bindings/microcontroller/Pin.h"
 
@@ -61,9 +62,6 @@ const mcu_pin_obj_t pin_## p_name = { \
     .peripheral = p_peripheral, \
 }
 
-#define NO_GPIO 0xff
-#define SPECIAL_CASE 0xfe
-
 // Using microcontroller names from the datasheet.
 // https://cdn-shop.adafruit.com/datasheets/ESP8266_Specifications_English.pdf
 // PIN(mcu name) // function notes | module name | huzzah name
diff --git a/esp8266/common-hal/nativeio/AnalogIn.c b/esp8266/common-hal/nativeio/AnalogIn.c
index bf46e930d..57ff607a3 100644
--- a/esp8266/common-hal/nativeio/AnalogIn.c
+++ b/esp8266/common-hal/nativeio/AnalogIn.c
@@ -36,7 +36,7 @@
 
 #include "user_interface.h"
 
-volatile bool adc_in_use = false;
+volatile bool adc_in_use __attribute__((aligned(4))) = false;
 
 void common_hal_nativeio_analogin_construct(nativeio_analogin_obj_t* self,
         const mcu_pin_obj_t *pin) {
@@ -54,3 +54,7 @@ uint16_t common_hal_nativeio_analogin_get_value(nativeio_analogin_obj_t *self) {
     // ADC is 10 bit so shift by 6 to make it 16-bit.
     return system_adc_read() << 6;
 }
+
+float common_hal_nativeio_analogin_get_reference_voltage(nativeio_analogin_obj_t *self) {
+    return 1.0f;
+}