M37702E6BFS Renesas Electronics America, M37702E6BFS Datasheet - Page 254

• Manufacturer Part Number: M37702E6BFS
• Description: EPROM MCU/8BIT CMOS EMULATION CH
• Manufacturer: Renesas Electronics America

Specifications of M37702E6BFS

• Accessory Type: Emulator EPROM MCU
• For Use With/related Products: 7702
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

WATCHDOG TIMER
9.2 Operation description
Fig. 9.2.1 Example of program runaway detection by Watchdog timer
9–6
(1) Example of program runaway detection
Watchdog timer
interrupt request occur
(program runaway detected)
becomes “0.” In the case that Watchdog timer is used to detect a program runaway, if writing to
address 60
occurs when the most significant bit of Watchdog timer becomes “0.” It means that a program
runaway has occurred.
address 5E
Write to the address 60
To reset the microcomputer after a program runaway, write “1” to the software reset bit (bit 3 at
Notes 1: Initialize (write to address 60
2: When the program runaway occurs, values of the data bank register (DT) and direct
page register (DPR) may be changed. When “1” is written to the software reset bit by
the addressing mode using DT and DPR, set values to DT and DPR again.
Watchdog timer becomes “0” (the watchdog timer interrupt request occurs).
16
16
Watchdog timer register
(Address 60
) in the watchdog timer interrupt routine.
is not performed owing to a program runaway, the watchdog timer interrupt request
Software reset bit
(Address 5E
Watchdog timer interrupt routine
16
16
)
(watchdog timer register) before the most significant bit of Watchdog timer
16
, b3)
Main routine
7702/7703 Group User’s Manual
RTI
16
) Watchdog timer before the most significant bit of
“1” (Note 2)
8-bit dummy data
Reset microcomputer
Watchdog timer initialized
Value of watchdog timer :
“FFF
16
” (Note 1)