UPD78F0838 Renesas Electronics Corporation., UPD78F0838 Datasheet - Page 339

• Manufacturer Part Number: UPD78F0838
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

9.2 Configuration of Watchdog Timer
WINDOW1 and WINDOW0
The watchdog timer includes the following hardware.
How the counter operation is controlled, overflow time, and window open period are set by the option byte.
of option byte (0080H)
of option byte (0080H)
CPU access signal
WDCS2 to WDCS0
f
OSC
Remark For the option byte, see CHAPTER 25 OPTION BYTE.
Window open period
Controlling counter operation of watchdog timer
Overflow time of watchdog timer
/2
WDTON of
option byte
Control register
(0080H)
Setting of Watchdog Timer
controller
Clock
input
Item
Table 9-2. Setting of Option Bytes and Watchdog Timer
Watchdog timer enable
register (WDTE)
Clear, reset control
Figure 9-1. Block Diagram of Watchdog Timer
Table 9-1. Configuration of Watchdog Timer
counter
17-bit
Preliminary User’s Manual U19748EJ1V0UD
CHAPTER 9 WATCHDOG TIMER
Watchdog timer enable register (WDTE)
Count clear
signal
2
2
10
17
error detector
CPU access
/f
/f
OSC
OSC
Internal bus
to
determination
Selector
Window size
Bits 6 and 5 (WINDOW1, WINDOW0)
Bit 4 (WDTON)
Bits 3 to 1 (WDCS2 to WDCS0)
signal
Configuration
Overflow
signal
Option Byte (0080H)
controller
output
Reset
Internal reset signal
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