l00% PRECISE CONTROL ON LOADING INTEL 8253, 8254 PROGRAMMABLE INTERVAL TIMER
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
Disclosed is a software procedure for a 100% precise control on loading the Intel 8253 or 8254 programmable interval timer. The procedure is applicable to the environment, as shown in the figure, where the input clock of counter 2 is from the output of counter 0. Usually, counter 0 is programmed to supply a steady input clock for counter 2, while counter 2 is programmed to time the desired time interval without any intervention from counter 0. This leaves some uncertainty on both the counting of counter 2 and the reading of the counter 2 value. The disclosed software procedure will precisely control the loading of counter 2 and leave no uncertainty on both the counting of counter 2 and the reading of the counter 2 value. The procedure is: 1) Ungate counter 2 - to disable counter 2.