void DelayUs() { _nop_(); _nop_(); _nop_(); _nop_(); } void DelayX(unsigned int x) { while (--x); } void DelayMs(unsigned int k) { unsigned int i,j; for(i=0;i<k;i++) { for(j=0;j<121;j++) {;} } }检查代码是否有缺少或错误

根据代码的逻辑和语法，没有明显的缺少或错误。但是需要注意的是，DelayMs() 函数中的延时时间是固定的，可能会因为不同的芯片或系统频率而导致延时时间不准确。建议使用定时器或其他精确的延时方式来实现精确的延时。此外，DelayUs() 函数中没有传入延时时间的参数，可能会导致无法实现预期的延时效果。

相关问题

void HC_SR04_Delayus(uint32_t usdelay) { __IO uint32_t Delay = usdelay * (SystemCoreClock / 8U /1000U/1000);//SystemCoreClock:系统频率 do { __NOP(); } while (Delay --); }

这段代码是用来实现一个微秒级别的延时函数。根据传入的延时时间（以微秒为单位），通过计算得到需要循环的次数，然后在循环中执行空操作（NOP）来实现延时。具体的计算方式是将传入的微秒数乘以系统时钟频率，然后除以8再除以1000再除以1000，得到需要循环的次数。在循环中每次循环都会执行一条空操作，直到循环次数减到0为止，从而实现了指定的延时时间。

void DelayUs(unsigned char Time) { unsigned char a; for(a=0;a<Time;a++) { NOP(); } }

This code snippet defines a function named "DelayUs" that takes an unsigned character (8-bit) argument named "Time". The purpose of this function is to introduce a delay in microseconds (hence the "Us" suffix) using a loop that executes "NOP()" (no operation) instructions.

Inside the function, a variable "a" is declared and initialized to zero. Then, a "for" loop is used that will run as many times as the "Time" argument specifies. Inside the loop body, a single NOP() instruction is executed. This instruction does nothing but take up one clock cycle of the processor. Therefore, as the loop iterates, it introduces a delay that is proportional to the value of "Time".

It is worth noting that this implementation of delay is not very precise or accurate, as it depends on the processor clock speed and other factors that could affect the execution time of the NOP() instruction. Additionally, this function assumes that the microcontroller is running at a clock frequency of at least 1 MHz, as a single NOP() instruction takes one clock cycle to execute.