I followed the instructions here (https://home-assistant.io/developers/creating_components) to create a custom component.
Excellent!
Now, how do I update the value in a periodically manner and not triggered by any event?
If I understand you right then you should create a sensor as a custom component (<config_dir>/custom_components/sensor/your_sensor.py). Sensor platforms have def update(): which take cares about the new values.