Fix up Analog classes: unify them at 16 bits and adds reference_voltage member

to make for easy conversion. Fixes #14.

3 files changed, 32 insertions, 3 deletions

diff --git a/shared-bindings/nativeio/AnalogIn.c b/shared-bindings/nativeio/AnalogIn.c
index 14e7efe1c..d41ba523f 100644
--- a/shared-bindings/nativeio/AnalogIn.c
+++ b/shared-bindings/nativeio/AnalogIn.c
@@ -50,7 +50,8 @@
 
 //| .. class:: AnalogIn(pin)
 //|
-//|   Use the AnalogIn on the given pin.
+//|   Use the AnalogIn on the given pin. The reference voltage varies by
+//|   platform so use ``reference_voltage`` to read the configured setting.
 //|
 //|   :param ~microcontroller.Pin pin: the pin to read from
 //|
@@ -126,11 +127,33 @@ mp_obj_property_t nativeio_analogin_value_obj = {
               (mp_obj_t)&mp_const_none_obj},
 };
 
+//|   .. attribute:: reference_voltage
+//|
+//|     The maximum voltage measurable. Also known as the reference voltage.
+//|
+//|     :return: the reference voltage
+//|     :rtype: float
+//|
+STATIC mp_obj_t nativeio_analogin_obj_get_reference_voltage(mp_obj_t self_in) {
+   nativeio_analogin_obj_t *self = MP_OBJ_TO_PTR(self_in);
+   return mp_obj_new_float(common_hal_nativeio_analogin_get_reference_voltage(self));
+}
+MP_DEFINE_CONST_FUN_OBJ_1(nativeio_analogin_get_reference_voltage_obj,
+                          nativeio_analogin_obj_get_reference_voltage);
+
+mp_obj_property_t nativeio_analogin_reference_voltage_obj = {
+    .base.type = &mp_type_property,
+    .proxy = {(mp_obj_t)&nativeio_analogin_get_reference_voltage_obj,
+              (mp_obj_t)&mp_const_none_obj,
+              (mp_obj_t)&mp_const_none_obj},
+};
+
 STATIC const mp_rom_map_elem_t nativeio_analogin_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_deinit),                 MP_ROM_PTR(&nativeio_analogin_deinit_obj) },
     { MP_ROM_QSTR(MP_QSTR___enter__),              MP_ROM_PTR(&nativeio_analogin___enter___obj) },
     { MP_ROM_QSTR(MP_QSTR___exit__),               MP_ROM_PTR(&nativeio_analogin___exit___obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_value), MP_ROM_PTR(&nativeio_analogin_value_obj)},
+    { MP_OBJ_NEW_QSTR(MP_QSTR_value),              MP_ROM_PTR(&nativeio_analogin_value_obj)},
+    { MP_OBJ_NEW_QSTR(MP_QSTR_reference_voltage),  MP_ROM_PTR(&nativeio_analogin_reference_voltage_obj)},
 };
 
 STATIC MP_DEFINE_CONST_DICT(nativeio_analogin_locals_dict, nativeio_analogin_locals_dict_table);
diff --git a/shared-bindings/nativeio/AnalogIn.h b/shared-bindings/nativeio/AnalogIn.h
index 781cd465c..ea5cfb84e 100644
--- a/shared-bindings/nativeio/AnalogIn.h
+++ b/shared-bindings/nativeio/AnalogIn.h
@@ -35,5 +35,6 @@ extern const mp_obj_type_t nativeio_analogin_type;
 void common_hal_nativeio_analogin_construct(nativeio_analogin_obj_t* self, const mcu_pin_obj_t *pin);
 void common_hal_nativeio_analogin_deinit(nativeio_analogin_obj_t* self);
 uint16_t common_hal_nativeio_analogin_get_value(nativeio_analogin_obj_t *self);
+float common_hal_nativeio_analogin_get_reference_voltage(nativeio_analogin_obj_t *self);
 
 #endif  // __MICROPY_INCLUDED_SHARED_BINDINGS_NATIVEIO_ANALOGIN_H__
diff --git a/shared-bindings/nativeio/AnalogOut.c b/shared-bindings/nativeio/AnalogOut.c
index 3e80b943d..32bd93274 100644
--- a/shared-bindings/nativeio/AnalogOut.c
+++ b/shared-bindings/nativeio/AnalogOut.c
@@ -113,7 +113,12 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(nativeio_analogout___exit___obj, 4, 4
 //|
 STATIC mp_obj_t nativeio_analogout_obj_set_value(mp_obj_t self_in, mp_obj_t value) {
    nativeio_analogout_obj_t *self = MP_OBJ_TO_PTR(self_in);
-   common_hal_nativeio_analogout_set_value(self, mp_obj_get_int(value));
+   uint32_t v = mp_obj_get_int(value);
+   if (v >= (1 << 16)) {
+       nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError,
+           "AnalogOut is only 16 bits. Value must be less than 65536."));
+   }
+   common_hal_nativeio_analogout_set_value(self, v);
    return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_2(nativeio_analogout_set_value_obj, nativeio_analogout_obj_set_value);