Z86E3016PSG Datasheet, PDF (141/348 Pages) Zilog, Inc. – Z86E3016PSG

Z8 CPU
User Manual
123
Single-pass counting mode, while a 1 written to this bit configures the
counter for Continuous mode.
The Counter/Timer can be stopped at any time by setting the Enable
Count bit to 0, and restarted by setting it back to 1. The Counter/Timer
will continue its count value at the time it was stopped. The current value
in the Counter/Timer can be read at any time without affecting the count-
ing operation.
Note: The prescaler registers are write-only and cannot be read.
New initial values can be written to the prescaler or the Counter/Timer
registers at any time. These values will be transferred to their respective
down counters on the next load operation. If the Counter/Timer mode is
continuous, the next load occurs on the timer clock following an end-of-
count. New initial values should be written before the load operation,
because the prescalers always effectively operate in Continuous count
mode.
The time interval (i) until end-of-count, is given by the equation:
i=txpxv
in which t = four times the internal clock period.
The internal clock frequency defaults to the external clock source (XTAL,
ceramic resonator, and others) divided by 2. Some Z8 microcontrollers
allow this divisor to be changed via the Stop-Mode Recovery register. See
the product data sheet for available clock divisor options.
t is equal to eight divided-by-XTAL frequency of the external clock
source for T1 (external clock mode only).
p = the prescaler value (1–63) for T₀ and T₁.
The minimum prescaler count of 1 is achieved by loading 000001xx. The
maximum prescaler count of 63 is achieved by loading 111111xx.
v = the Counter/Timer value (1–256)
UM001602-0904
Counters and Timers