1us Delay using 89c2051

Hey all, I do use atmel 89c2051 controller. I wanna generate a signal with 1us On time and 1us OFF time. I am tired of trying with different method. so plz suggest me some idea !!!

well how much is your crystal frequency?

I use 11.0592 MHZ crystal.

you can generate 1uS delay for the reason, your single clock cycle itself is 1.085uS. you need higher speed crystal to generate that delay.

Ok. My intention is not exactly producing 2us delay. I need to generate a On time of 3 us and off time 27 us. Pulse of 10% duty cycle. and this dut cyle is variable from 10% to 90%

One simple solution is to change your crystal frequency to 12Mhz to get exactly
1us / 1 Byte Command
example
2uS ON
3uS Off

main:
setb P1.0 ;1us 
nop   ;1uS 
clr P1.0 ;1us  
jmp main ;2us
 

Yep, thanks for the code, but i am looking for implement the same using timer or DJNZ loop, so that I can change the delay in a generic way.I attempted using timer, but I couldn't get On or OFF period lesser than 5 ns.

well you can use loops if your delay is a bit longer but DJNZ instruction itself take 2 cycles.

void delay_us(unsigned int us)
{
int a=(us)/13; //BY TRIAL
while(a--);
}

11.0592*2 MHZ

mov R1,#01 ;or any other value here
djnz R1,#01,decrement
decrement: dec R1


That is with a 12Mhz crystal. However, minimum with djnz is 2us!