In electronic circuit design, crystal excitation is an important part of clock source, and its stability is directly related to the normal operation of the system.  However, in practical applications, the frequency of crystal vibration is not correct, which undoubtedly brings trouble to the normal operation of the circuit.

In view of this problem, it is necessary to investigate the possible causes one by one and provide corresponding solutions.

1. The crystal oscillator pin contact is poor or wrong: when the crystal oscillator pin contact is poor or wrong, it will lead to the circuit can not work correctly, thus affecting the output frequency of the crystal oscillator.  Therefore, when you encounter the problem of incorrect crystal frequency, you must first check whether the pin of the crystal vibration is connected correctly and whether the contact is good.

2. The crystal frequency is wrong or insufficient precision: the frequency of the crystal vibration is the number of times it oscillates per second, if the wrong frequency or precision is not high enough crystal vibration is selected, it can not meet the circuit's clock frequency accuracy requirements, resulting in incorrect frequency.  Therefore, when selecting the crystal oscillator, it is necessary to ensure that its frequency and accuracy meet the circuit design requirements.

3. Check the quality of crystal vibration and ensure that it meets the specifications: crystal vibration quality and specifications directly affect its stability and accuracy.  If there are quality problems or specifications are not met, the frequency may be incorrect.  Therefore, it is necessary to check the crystal quality to ensure that it meets the specifications of the circuit design.

4. Reduce the impact of temperature and electromagnetic interference on crystal vibration: crystal vibration is greatly affected by working temperature and electromagnetic interference, high temperature and strong interference may lead to abnormal output frequency.  Therefore, it is necessary to check the operating temperature and electromagnetic interference, and take measures to reduce their impact on the crystal shaker as much as possible.

5. There is a problem with the MCU clock source: If there is a problem with the MCU clock source, the frequency output of the crystal oscillator may also be abnormal. Therefore, the MCU clock source needs to be carefully checked to confirm that there is no potential risk.

In short, by checking the above reasons one by one and dealing with them accordingly, such problems can be effectively solved, and finally ensure the normal operation of the entire circuit system.