1. A decoding method, applied to a data signal comprising a plurality of bits, each of which having a same bit cycle, a plurality of sampled data being generated by sampling the data signal, the decoding method comprising steps of: (a) setting a first interval and a second interval in the bit cycle; (b) generating a first count according to the sampled data in the first interval corresponding to a first logic level; (c) generating a second count according to the sampled data in the second interval corresponding to a second logic level; and (d) determining a digital logic value of the specific bit according to the first count and the second count.