[Feature Request] Simulate simple I/O in IO_PCA9685pwm

[ProfessorKa0Z]

I suggest adding a _write function to IO_PCA9658pwm, analogous to the one implemented in IO_PCA9685.cpp. This would permit simple on/off control of an output.

This would be specifically useful to trigger turnout solenoids with the Adafruit PCA9685-based motor shield in an EX-RAIL script, since the servo-based model in IO_PCA9685 has issues with I2c writes being skipped in rapid SET/RESET sequences. I've discussed this in the EX-RAIL Discord.