Z8F1680SH020SG Datasheet, PDF (147/412 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F1680 Series
Product Specification
122
10.2.3. Multi-Channel Timer Clock Prescaler
The prescaler allows the system clock signal to be decreased by factors of 1, 2, 4, 8, 16,
32, 64 or 128. The PRES[2:0] bit field in the MCTCTL1 Register controls prescaler
operation. The PRES field is buffered for the prescale value to change only on a Multi-
Channel Timer end-of-cycle count. The prescaler has no effect when the T_IN is selected as
the clock source.
10.2.4. Multi-Channel Timer Start
The Multi-Channel Timer starts counting when the TEN bit in the MCTCTL1 Register is
set and the clock source is active. In Count Modulo or Count Up/Down mode, the timer
counting can be stopped without disabling the timer by setting the Reload Register to 0.
The timer will then stop when the counter next reaches 0. Writing a nonzero value to the
Reload Register restarts the timer counting.
10.2.5. Multi-Channel Timer Mode Control
The Multi-Channel Timer supports two modes of operation: Count Modulo and Count up/
down. The operating mode is selected with the TMODE[1:0] field in the MCTCTL1
Register. The timer modes are described below in Table 68.
Table 68. Timer Count Modes
TMODE
00
01
10
11
Timer Mode
Count Modulo
Reserved
Count Up/Down
Reserved
Description
Timer counts up to Reload Register value. Then it is reset to 0000H and
counting resumes.
Timer counts up to Reload and then counts down to 0000H. The Count up/
down cycle continues.
10.2.6. Count Modulo Mode
In the Count Modulo Mode, the Timer counts up to the Reload Register value (max value
= FFFFH). Then it is reset to 0000H and counting resumes. As shown in Figure 15, the
counting cycle continues with Reload + 1 as the period. A timer count interrupt request is
generated when the timer count resets from Reload to 0000H. If Count Modulo is selected
when the timer count is greater than Reload, the timer immediately restarts counting from
zero.
PS025015-1212
PRELIMINARY
Multi-Channel Timer