PWM conflcit

[MarcScott]

Code I ran:

from picozero import LED
from time import sleep

blue = LED(12)
green = LED(11)
white = LED(15)
purple = LED(13)
red = LED(8)
orange = LED(9)
grey = LED(14)
yellow = LED(10)

Error I received

Traceback (most recent call last):
  File "<stdin>", line 9, in <module>
  File "picozero.py", line 229, in LED
  File "picozero.py", line 177, in __init__
  File "picozero.py", line 138, in __init__
  File "picozero.py", line 149, in _check_pwm_channel
PWMChannelAlreadyInUse: PWM channel 4B is already in use by pin 25

This was using picozero.py from Master

[MarcScott]

Can be resolved with

orange = LED(9, use_pwm=False)

[martinohanlon]

This is "by design", if you try and use 2 pins which share a PWM channel you will receive the error.

We could:

• have the LED factory return a DigitalLED by default rather than a PWMLED - I dont think this is a great user experience though, you get reduce functionality from a digital led.
• improve the error message

Advice on what to do could be added to the current error message e.g.

PWMChannelAlreadyInUse: PWM channel 4B is already in use by pin 25. Use different free pin.

A more complicated solution would be to provide feedback on the which pins are still free e.g.

PWMChannelAlreadyInUse: PWM channel 4B is already in use by pin 25. Use one of these free pins (7,8,12,14,18).

^ the more complex solution is not full proof though, it would only know the pins which hadnt been used by picozero, it couldnt cater for solutions where the user had mixed the use of machine and picozero.

[martinohanlon]

We will change the error message to:

PWMChannelAlreadyInUse: PWM channel 4B is already in use by pin 25. Use different free pin.

[martinohanlon]

In dev branch

[martinohanlon]

pushed to master