It looks like your 'distance sensor' is a HC-SR04 which requires a
minimum trigger pulse of 10 us for reliable operation. With your pulse of 5us, pulsein might be returning an erratic value over 100.
It looks like your 'distance sensor' is a HC-SR04 which requires a
minimum trigger pulse of 10 us for reliable operation. With your pulse of 5us, pulsein might be returning an erratic value over 100.