QUERY · ISSUE
ESP32 Confusing behaviour of PWM after soft reset
port-esp32
Consider:
from machine import Pin, PWM
pin = Pin(23, Pin.OUT)
pwm = PWM(pin, freq=38000, duty=338)
This works as expected. If you issue ctrl-d the waveform on the pin continues unchanged. If you paste the above code again, you cause a low output with
pwm.duty(0)
Subsequently changing the duty value to a value > 0 has no effect. This is surprising.
There is a simple workround of issuing pwm.deinit() at the start. The current state could be confusing to newcomers. It should either be documented or changed so that a soft reset de-initialises any PWM instance.
CANDIDATE · PULL REQUEST
ports/mimxrt: Three bug fixes.
port-mimxrt
- Fix stopping the Pin IRQ by calling Pin.irq() with handler set to None. It worked before, but caused in some cases a crash during soft reset.
- Align the PWM edge cases of duty_u16=0 and duty_u16=65536 for all three internal PWM mechanisms. For duty_u16=0, the output is set to low level, for duty_u16=65536 the output is set to high level.
- Deinitialize all UART instances on soft reset. Otherwise the board will crash, if new data at a previously used UART arrives before it is instantiated again.