Multiresolution TIMER Routine
Original Publication Date: 1985-Dec-01
Included in the Prior Art Database: 2005-Feb-19
A method is described to allow the Motorola 8051 microprocessor to use 8-bit time delay tables (1 byte per delay) without being restricted to the range and resolution of the internal 8-bit timer mode. Many control programming tasks require time delays between the steps of the task. These delays can be implemented in the 8051's 16- bit timer mode. Assuming a 12 MHz clock rate, this timer mode has a resolution of 1 msec and can time delays up to 65.5 msec. Unfortunately, this timer mode requires 2 bytes per delay in a read-only storage (ROS) table. To save space in ROS, the 8-bit mode of the timers can be used. This mode uses only 1 ROS for a maximum delay of 8.2 msec. The method presented here allows a programmer to select any resolution from 1-255 msec using only 1 ROS byte per delay.