KSWang:
Thank you very much.
Your library is awesome.
However, I want to use with five ultrasonic sensors and one hall sensor.
It is embarrassed if there are any delay time in loop.
Is it mean it will be few delay time/ or no delay if I use the similar way like with calling NewPing five times?
Few months ago I had a similar requirement of using 4 ultrasonic sensors together attached to 4 corners. Instead of killing time hassling and fine tuning 4 separate sensors I had bought a board which had 4 transducers/probe with 1 board. I believe it had UART output of distances so not much calculation code required on the micro-controller side.
Edit: Found out the item I had bought couple months ago. It was something like this 1-to-4 Waterproof Integrated Ultrasonic Ranging Sensor Smart Trash Can arduino | eBay. Also here is another model which showed up in the search results serving the same purpose: https://www.ebay.com/itm/254203570456