gc80c520a CORERIVER Semiconductor, gc80c520a Datasheet - Page 37

• Manufacturer Part Number: gc80c520a
• Description: Midas1.0 Family Mask Rom/eprom/romless 8-bit Turbo Microcontrollers
• Manufacturer: CORERIVER Semiconductor

6.2.3 WDT (Watchdog Timer)
The Watchdog timer is a free-running timer with programmable time-out intervals. It is available for a
system monitor, a time-base generator or an event timer. It allows an automatic recovery from software
upset due to some cause including external noise. It is a kind of counter with the programmable bit length.
It counts the system clock pulses. Software can always clear the value of the watchdog timer. When the
count rolls over from all 1s to all 0s, the time-out occurs. At that time, the watchdog interrupt flag is set.
The watchdog interrupt will occur if EWDT (watchdog interrupt enable) and EA (global enable) are set. If
the watchdog reset is enabled by setting the bit EWT to logic 1, the watchdog reset will occur after 512
clock cycles since the watchdog timer interrupt flag is set, However, the watchdog timer can be cleared
by setting the bit RWT to logic 1 during the delay of 512 clock cycles. Then the watchdog reset will not
occur. The watchdog interrupt and reset may be used independently of each other. So a user can use
them separately or together. Figure 6-14 shows the block diagram for Watchdog timer.
MiDAS1.0 Family
LVD_OFF
PFI Pulse
PD
Figure 6-13 LVD Block Diagram
LVD
PFI
BGS
POR Pulse
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EPFI
POR
POF
POR Reset
PFI interrupt