GD32F4(6)： Crystal oscillator causes serial port garbled

1. System environment

• System ：win10

• IDE：keil5

• Development board ：GD Official evaluation board GD32450Z_EVAL

• User manual version ：GD32F4xx_yonghushouce_Rev2.6.pdf

• Standard library version ：GD32F4xx_Demo_Suites_V2.5.0

2. The serial port of the development board is garbled

The official development board crystal vibrators are 25M Of , When designing by yourself, you may use external crystal oscillators with other values , You need to design your own clock program , Fortunately GD There are many official programs , You change the macro by , You can switch back and forth under different crystal oscillators , as follows ：

you 're right , In this way, it is set to 200M 了 , Please refer to my other article for the specific principle ：GD32F4(5):GD32F450 The clock is configured as 200M process analysis

Now the system is 200M you 're right , But the peripheral does not know the current clock of the system , That will lead to an error in the initialization clock of the peripheral , For example, when using serial port , You will find that the data is garbled , This is because there is a macro that defines the clock that needs to be modified , as follows ：

explain ： When using peripherals , Peripheral clock initialization will call rcu_clock_freq_get(rcu_clock_freq_enum clock) Get clock , Here's the picture ：

This function will read the configured crystal oscillator clock and the registers related to the clock configuration , Work out each bit Clock delay required , When the calculated delay is equal to the real delay , There will be no garbled code .