Update D13 to LED, add PWM example.

Author: kattni

docs/design_guide.rst

@@ -99,7 +99,7 @@ For example, a user can then use ``deinit()```::
     import board
     import time
 
-    led = digitalio.DigitalInOut(board.D13)
+    led = digitalio.DigitalInOut(board.LED)
     led.direction = digitalio.Direction.OUTPUT
 
     for i in range(10):
@@ -119,7 +119,7 @@ Alternatively, using a ``with`` statement ensures that the hardware is deinitial
     import board
     import time
 
-    with digitalio.DigitalInOut(board.D13) as led:
+    with digitalio.DigitalInOut(board.LED) as led:
         led.direction = digitalio.Direction.OUTPUT
 
         for i in range(10):

shared-bindings/digitalio/__init__.c

@@ -50,9 +50,9 @@
 //| For example::
 //|
 //|   import digitalio
-//|   from board import *
+//|   import board
 //|
-//|   pin = digitalio.DigitalInOut(D13)
+//|   pin = digitalio.DigitalInOut(board.LED)
 //|   print(pin.value)
 //|
 //| This example will initialize the the device, read
@@ -61,11 +61,11 @@
 //|
 //| Here is blinky::
 //|
-//|   import digitalio
-//|   from board import *
 //|   import time
+//|   import digitalio
+//|   import board
 //|
-//|   led = digitalio.DigitalInOut(D13)
+//|   led = digitalio.DigitalInOut(board.LED)
 //|   led.direction = digitalio.Direction.OUTPUT
 //|   while True:
 //|       led.value = True

shared-bindings/frequencyio/__init__.c

@@ -46,11 +46,11 @@
 //|
 //| For example::
 //|
-//|   import frequencyio
 //|   import time
-//|   from board import *
+//|   import frequencyio
+//|   import board
 //|
-//|   frequency = frequencyio.FrequencyIn(D13)
+//|   frequency = frequencyio.FrequencyIn(board.D11)
 //|   frequency.capture_period = 15
 //|   time.sleep(0.1)
 //|

shared-bindings/pulseio/PulseOut.c

@@ -59,7 +59,7 @@
 //|           import board
 //|
 //|           # 50% duty cycle at 38kHz.
-//|           pwm = pulseio.PulseOut(board.D13, frequency=38000, duty_cycle=32768)
+//|           pwm = pulseio.PulseOut(board.LED, frequency=38000, duty_cycle=32768)
 //|           #                             on   off     on    off    on
 //|           pulses = array.array('H', [65000, 1000, 65000, 65000, 1000])
 //|           pulse.send(pulses)

shared-bindings/pwmio/PWMOut.c

@@ -86,21 +86,37 @@ void common_hal_pwmio_pwmout_raise_error(pwmout_result_t result) {
 //|         :param int frequency: The target frequency in Hertz (32-bit)
 //|         :param bool variable_frequency: True if the frequency will change over time
 //|
-//|         Simple LED fade::
+//|
+//|         Simple LED on::
+//|
+//|           import pwmio
+//|           import board
+//|
+//|           pwm = pwmio.PWMOut(board.LED)
+//|
+//|           while True:
+//|               pwm.duty_cycle = 2 ** 15  # Cycles the pin with 50% duty cycle (half of 2 ** 16) at the default 500hz
+//|
+//|         PWM LED fade::
 //|
 //|           import pwmio
 //|           import board
 //|
-//|           pwm = pwmio.PWMOut(board.D13)     # output on D13
-//|           pwm.duty_cycle = 2 ** 15            # Cycles the pin with 50% duty cycle (half of 2 ** 16) at the default 500hz
+//|           pwm = pwmio.PWMOut(board.LED)  # output on LED pin with default of 500Hz
+//|
+//|           while True:
+//|               for cycle in range(0, 65535):  # Cycles through the full PWM range from 0 to 65535
+//|                   pwm.duty_cycle = cycle  # Cycles the LED pin duty cycle through the range of values
+//|               for cycle in range(65534, 0, -1):  # Cycles through the PWM range backwards from 65534 to 0
+//|                   pwm.duty_cycle = cycle  # Cycles the LED pin duty cycle through the range of values
 //|
 //|         PWM at specific frequency (servos and motors)::
 //|
 //|           import pwmio
 //|           import board
 //|
 //|           pwm = pwmio.PWMOut(board.D13, frequency=50)
-//|           pwm.duty_cycle = 2 ** 15                  # Cycles the pin with 50% duty cycle (half of 2 ** 16) at 50hz
+//|           pwm.duty_cycle = 2 ** 15  # Cycles the pin with 50% duty cycle (half of 2 ** 16) at 50hz
 //|
 //|         Variable frequency (usually tones)::
 //|

shared-bindings/pwmio/__init__.c

@@ -45,11 +45,11 @@
 //|
 //| For example::
 //|
-//|   import pwmio
 //|   import time
-//|   from board import *
+//|   import pwmio
+//|   import board
 //|
-//|   pwm = pwmio.PWMOut(D13)
+//|   pwm = pwmio.PWMOut(board.LED)
 //|   pwm.duty_cycle = 2 ** 15
 //|   time.sleep(0.1)
 //|

tests/circuitpython-manual/audiopwmio/wavefile_pause_resume.py

@@ -3,7 +3,6 @@
 import board
 import digitalio
 import time
-import math
 import os
 
 trigger = digitalio.DigitalInOut(board.D4)

tests/circuitpython-manual/audiopwmio/wavefile_playback.py

@@ -3,7 +3,6 @@
 import board
 import digitalio
 import time
-import math
 import os
 
 trigger = digitalio.DigitalInOut(board.D4)