The microcontroller part of digital frequency meter is actually very easy to do, which is nothing more than using frequency measurement method (two timers cooperate, one timer and one counter) to process high-frequency signals, and using period measurement method to process low-frequency signals (an external interrupt+a timer). Although the program volume is a bit, if it is in C language, it is 500 lines.

The hardest part is the front-end simulation part. The incoming signal is not so obedient. Some signals are small in amplitude, only tens of mv, and some are on one side, such as the whole waveform is on the positive half axis, and so on. Some frequencies are very high, such as 10MHz or above, and some amplitudes are very high, such as10 V. If it is sent directly to the single chip microcomputer, it will definitely become warped. They need to be conditioned into a pulse square wave with a peak-to-peak value of 5V and a low level of 0V by analog circuits and frequency dividing circuits before being sent to a single chip microcomputer for measurement. This front-end circuit, especially at high frequency, is not easy to do. Also consider the accuracy requirements.

At this time, the simulation software really can't help. With experience and technology, a little experiment was finally completed.

PS: You're not going to take part in the competition, are you?

This topic looks familiar.

This topic is made up, it will kill people.