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

to make for easy conversion. Fixes #14.

atmel-samd/common-hal/nativeio/AnalogIn.c

@@ -47,10 +47,10 @@ void common_hal_nativeio_analogin_construct(nativeio_analogin_obj_t* self,
     struct adc_config config_adc;
     adc_get_config_defaults(&config_adc);
 
+    config_adc.reference = ADC_REFERENCE_INTVCC1;
+    config_adc.gain_factor = ADC_GAIN_FACTOR_DIV2;
     config_adc.positive_input = self->pin->adc_input;
-    config_adc.resolution = ADC_RESOLUTION_CUSTOM;
+    config_adc.resolution = ADC_RESOLUTION_16BIT;
-    config_adc.accumulate_samples = ADC_ACCUMULATE_SAMPLES_16;
-    config_adc.divide_result = ADC_DIVIDE_RESULT_16;
     config_adc.clock_prescaler = ADC_CLOCK_PRESCALER_DIV128;
 
     adc_init(&self->adc_instance, ADC, &config_adc);
@@ -82,3 +82,7 @@ uint16_t common_hal_nativeio_analogin_get_value(nativeio_analogin_obj_t *self) {
     adc_disable(&self->adc_instance);
     return data;
 }
+
+float common_hal_nativeio_analogin_get_reference_voltage(nativeio_analogin_obj_t *self) {
+    return 3.3f;
+}

atmel-samd/common-hal/nativeio/AnalogOut.c

@@ -67,5 +67,6 @@ void common_hal_nativeio_analogout_deinit(nativeio_analogout_obj_t *self) {
 
 void common_hal_nativeio_analogout_set_value(nativeio_analogout_obj_t *self,
         uint16_t value) {
-    dac_chan_write(&self->dac_instance, DAC_CHANNEL_0, value);
+    // Input is 16 bit but we only support 10 bit so we shift the input.
+    dac_chan_write(&self->dac_instance, DAC_CHANNEL_0, value >> 6);
 }

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) ||
+    if (pin == &pin_TOUT) {
-            ((READ_PERI_REG(pin->peripheral) &
+        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) {

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__

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

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;
+}

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);

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__

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);