将单片机的系统时钟设置成56M，用UART1，将第1题实现的时钟功能，传给第二个单片机，实现双单片机同步时钟。-The microcontroller system clock is set to 56M, with UART1, the first question to achieve the clock function, passed to the second microcontroller to achieve dual-chip synchronous clock.