Controller Circuit

Function of timer which is main was to measure time. When a timer applied to measure time, it will increase one every one machine cycles. Every machine cycle requires 12 crystal modulations. Hence, if a 89C51 with crystal 11,059 MHZ, hence timer every the second will worth:

11.059.000/12=921.583

Equally, there are 921583 times chopper in every the second. Not like instructions which able to eat one to four machine cycles, a timer always consistent increased one every once machine cycle. So, if it is wanted a timer which is valuable 50000, it mean eats time equal:

50.000/921.583=0,0542

Equally, required time 0,052 second is to get timer which has worth 50000. Pass way of similar, if wanted to get timer 0,05 seconds, hence required by timer which finite count:

0, 05 x 921.583=46.079, 15

This means we need to monitor the counter from timer so reaching price 46079. Although not really precision because eliminating calculation 0,15; but enough closing and can be tolerance.