Delay Calculations

Repeating a sequence of instructions a certain number of times is called a LOOP

The loop is one of most widely used actions that any microcontroller performs

  MOV  A,#0

  MOV  R2,#10

AGAIN:

  ADD  A,#25

  DJNZ  R2,AGAIN

  MOV  R5,A

In this program R2 is used as counter. The counter is first set to 10. In each iteration  the instruction DJNZ decrements R2 and checks its value. If R2 is not zero it jumps to the target address associated with the label “AGAIN”. This looping action continues until R@ becomes zero. After R2 becomes zero, it terminates the loop and executes the instruction immediately below it, in this case the  MOV  R5,A