Introduction - If you have any usage issues, please Google them yourself
This design adopts the direct frequency measurement method, based on measured signal within 1 s rise along the number directly to measure the frequency, the error in the plus or minus 1 hz, has the advantages of simple, intuitive, and small error. When measuring less than 1 hz frequency, due to the delay, outside influence factors, such as possible counter will get 1 hz, digital tube display "L" or "1", when measured as 1 hz and cannot determine whether the value is 1 hz, so the design of the lower frequency of 2 hz, rather than 1 hz. Duty ratio using small signal than the measured signal measurement, the error of plus or minus 1 hz.