I'd like to create a node for the Software PWM which supports any GPIO pins and support a fixed frequency(38kHz) and fixed duty cycle(50%).
In other word, I just need 5~6 GPIO pins that output 38kHz/50% PWM signal.
@wester.weerdt A node will NOT control the GPIO, it would control the library or custom code that would control the GPIO. You need to figure out that part first.
You might also consider looking at an add-on board with true hardware PWM.
Is this for a specific IR communication? or general purpose "programmable"
Then find some way to do that via library, custom code, hardware PWM, etc... then once you have that, and not before, you can make your custom node to control the process.
Google for LIRC (Linux Infrared Remote Control) library and how to install it.
With this lib you can send Ir commands from the command Line and thus with the EXEC node.