# Configuring Clock<a name="EN-US_TOPIC_0314628515"></a>

1.  Configure the clock pin.

    Click the  **Pinout & Configuration**  tab, select  **RCC**  from the **System Core**  drop-down list box on the left, and set  **High Speed Clock \(HSE\)**  to  **Crystal/Ceramic Resonator**, that is, the external crystal oscillator is used as the HSE clock source, as shown in the following figure.

    **Figure  1**  Configuring clock pins<a name="fig197751515215"></a>  
    ![](figures/configure_clock_pins.png "configuring-clock-pins")

2.  Configure the clock frequency.

    Click the  **Clock Configuration**  tab. The highest clock frequency of the STM32F407 chip is 168 MHz. Enter  **168**  in the  **HCLK**  field and press  **Enter**  to complete the configuration, as shown in the following figure. The configuration methods of other development boards are similar.

    **Figure  2**  Configuring clock frequency<a name="fig118761971236"></a>  
    ![](figures/configure_clock_freq.png "configuring-clock-freq")
