9. Timers
Rev.3.00 Jul. 19, 2007 page 209 of 532
REJ09B0397-0300
Section 9 Timers
9.1 Overview
The H8/3857 Group is provided with four timers (timers A, B, C, and F), and the H8/3854 Group
with three (timers A, B, and F). The H8/3857F and H8/3854F also have an on-chip watchdog
timer for flash memory programming control.
Table 9.1 outlines the functions of timers A, B, C, F, and the watchdog timer.
Table 9.1
Timer Functions
Name
Functions
Internal Clock
Event
Input Pin
Waveform
Output Pin
Remarks
Timer A
•
8-bit timer
•
Interval timer
φ
/8 to
φ
/8192
(8 choices)
⎯
⎯
•
8-bit timer
•
Time base
φ
W
/128
(choice of 4
overflow periods)
⎯
⎯
•
8-bit timer
•
Clock output
φ
/4 to
φ
/32,
φ
W
/4 to
φ
W
/32
(8 choices)
⎯
TMOW
Timer B
•
8-bit timer
•
Interval timer
•
Event counter
φ
/4 to
φ
/8192
(7 choices)
TMIB
⎯
Timer C
*
1
•
8-bit timer
•
Interval timer
•
Event counter
•
Choice of up- or down-
counting
φ
/4 to
φ
/8192,
φ
W
/4 (7 choices)
TMIC
⎯
Counting
direction can be
controlled by
software or
hardware
Timer F
•
16-bit timer
•
Event counter
•
Can be used as two
independent 8-bit
timers
•
Output compare
φ
/2 to
φ
/32
(4 choices)
TMIF TMOFL
TMOFH
Watchdog
timer
*
2
•
Generates reset signal
on overflow of 8-bit
counter
φ
/64 to
φ
/8192
(8 choices)
⎯
⎯
Provided only in
H8/3857F and
H8/3854F
Notes: 1. Timer C is a function of the H8/3857 Group only, and is not provided in the H8/3854
Group.
2. The watchdog timer is used by the flash memory programming control program.
Summary of Contents for F-ZTAT H8 Series
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