Chapter 18:
Pulse Width Counter (PWC) Timer
18.1 Outline
This module is a multi-function 16-bit up-counter with a reload function and a function for counting pulse
widths on the input signal. The module hardware consists of a 16-bit up-counter, input pulse divider, divide
ratio control register, four count input pins, one pulse output pin, and a 16-bit control register. These per-
form the following functions.
Timer function:
•
Interrupt requests can be generated at specified time intervals.
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A pulse signal can be output synchronized with the timer period.
•
The counter clock can be selected from three internal clocks.
Pulse width count function:
•
Measures the time between events on an external pulse input.
•
The counter clock can be selected from three internal clocks.
Count modes H pulse width ( ⇑ to ⇓ )/L pulse width ( ⇓ to ⇑ )
•
•
Using the 8-bit input divider, the module can divide an input pulse signal by 2
and measure the period.
•
An interrupt request can be generated on count completion.
•
Single-shot or continuous counting can be selected.
The MB90580 series contains one PWC timer channels.
Rising edge period ( ⇑ to ⇑ )/Falling edge period ( ⇓ to ⇓ )
Inter-edge count ( ⇑ or ⇓ to ⇓ or ⇑ )
2n
(n = 1, 2, 3, 4)