hd64338342hw Renesas Electronics Corporation., hd64338342hw Datasheet - Page 353

• Manufacturer Part Number: hd64338342hw
• Description: Renesas 8-bit Single-chip Microcomputer H8 Family/h8/300l Super Low Power Series
• Manufacturer: Renesas Electronics Corporation.

4. Port Mode Register 3 (PMR3)
PMR3 is an 8-bit read/write register, mainly controlling the selection of pin functions for port 3
pins. Only the bit relating to the watchdog timer is described here. For details of the other bits,
see section 8, I/O Ports.
Bit 5: Watchdog timer source clock select (WDCKS)
WDCKS
0
1
9.6.3
The watchdog timer has an 8-bit counter (TCW) that is incremented by clock input ( /8192 or
selected when WDCKS is cleared to 0, and w/32 when set to 1. When TCSRWE = 1 in TCSRW,
if 0 is written in B2WI and 1 is simultaneously written in WDON, TCW starts counting up. When
the TCW count value reaches H'FF, the next clock input causes the watchdog timer to overflow,
and an internal reset signal is generated one base clock ( or
signal is output for 512 clock cycles of the
TCW to count up from the written value. The overflow period can be set in the range from 1 to
256 input clocks, depending on the value written in TCW.
w/32). The input clock is selected by bit WDCKS in port mode register 3 (PMR3): /8192 is
Bit
Initial value
Read/Write
Timer Operation
Description
/8192 selected
w/32 selected
—
—
7
1
—
—
6
1
—
—
5
1
OSC
—
—
4
1
clock. It is possible to write to TCW, causing
AECKSTP
R/W
3
1
Rev. 6.00 Aug 04, 2006 page 317 of 680
SUB
WDCKSTP
) cycle later. The internal reset
R/W
2
1
PWCKSTP
R/W
1
1
REJ09B0145-0600
Section 9 Timers
(initial value)
LDCKSTP
R/W
0
1