However, for some applications it may be necessary to still be able to use RPi.GPIO after keypad cleanup, for example if the keypad should be active only occasionally (i.e. instantiated and destroyed multiple number of times).
When using this keypad library simulatenously with any HD44780 LCD display library based on RPi.GPIO, currently it is necessary to perform keypad cleanup at the very end. Otherwise, the following error will appear when trying to clear the display with lcd.clear() after keypad cleanup:
RuntimeError: Please set pin numbering mode using GPIO.setmode(GPIO.BOARD) or GPIO.setmode(GPIO.BCM)
According to RPi.GPIO documentation, GPIO.cleanup() should be called at the end any program. This can be easily achieved by simply placing GPIO.cleanup() at the end of the script separately or using exit handlers (atexit) manually by the library user.
For convenience and compability purposes, the suggested solution is to call GPIO.cleanup() conditionally, depending on the value of a boolean parameter (enabled by default). Otherwise, GPIO.remove_event_detect() should be called to unregister all interrupts. This will allow developers to configure the behaviour depending on the application.
The current implementation of
Keypad.cleanup()always callsGPIO.cleanup():https://github.com/brettmclean/pad4pi/blob/0e560a1ab67866cbedf8df9237316765debab2f1/pad4pi/rpi_gpio.py#L165-L168
However, for some applications it may be necessary to still be able to use RPi.GPIO after keypad cleanup, for example if the keypad should be active only occasionally (i.e. instantiated and destroyed multiple number of times).
When using this keypad library simulatenously with any HD44780 LCD display library based on RPi.GPIO, currently it is necessary to perform keypad cleanup at the very end. Otherwise, the following error will appear when trying to clear the display with
lcd.clear()after keypad cleanup:According to RPi.GPIO documentation,
GPIO.cleanup()should be called at the end any program. This can be easily achieved by simply placingGPIO.cleanup()at the end of the script separately or using exit handlers (atexit) manually by the library user.For convenience and compability purposes, the suggested solution is to call
GPIO.cleanup()conditionally, depending on the value of a boolean parameter (enabled by default). Otherwise,GPIO.remove_event_detect()should be called to unregister all interrupts. This will allow developers to configure the behaviour depending on the application.