Writing of C51 delay function delay-EEWORLD

Collect

For example, to write a delay function with a delay of 10ms: (12M crystal oscillator)

void delay_10ms()

{

unsigned char i,j,k;

for(i=5;i>0;i--)

{

for(j=4;j>0;j--)

{

for(k=248;j>0;j--);

}

Principle: 3 layers of for loops, the number of loops is NUM = 4X5X248 = 4960 times. Each loop has a conditional judgment (such as i > 0) and a self-decrement statement (such as i--), so each loop consumes two machine cycles.

Therefore, the total machine cycles consumed is SUM = NUM x 2 = 9920

Because the frequency of the 12M crystal oscillator is 1us per machine cycle, the time taken for this function is 9920us = 9.920 ms, which is approximately 10ms. If the assignment statement, stack push and pop operations are included, the total time is about 10ms.

Keywords：C51 Reference address：Writing of C51 delay function delay

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