Common Errors in Delay Functions in MCUs-EEWORLD

Collect

   Sometimes when a long delay is needed, you can use a loop or pass a larger parameter. However, when passing a larger parameter, you must clearly see the parameter type and the range of values that this type can represent.
   For example, in the AD conversion program I wrote, the conversion time must be as long as 30ms to have valid data output. If the time is too short, it will not have an immediate effect. The maximum value of unsigned char is 255. If it is larger, a loop must be used.
   Below is the original code:
#include
#include
sbit wr = P3^6;
sbit rd = P3^7;
sbit dula = P2^6;
sbit wela = P2^7;
unsigned char j,k,aa;
void delay(unsigned char i) //maximum value 255
{
for(j=i;j>0;j--)
for(k=125;k>0;k--);
}
void main()
{
unsigned char a;
while(1)
{
wela = 1; //select P0 of 74hc573
P0 = 0;       //select ADCS
wr = 0; //start adc0804, write analog signal
_nop_();
wr = 1;
delay(10);
//         for(a = 20;a>0;a--)
delay(255); //wait for conversion
rd = 0; //AD read enable
}
}
[Note] This code is passed in TX-1C

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