UPD784224 Datasheet, PDF (54/92 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784224, 784225, 784224Y, 784225Y
11. RESET FUNCTION
When a low-level signal is input to the RESET pin, the system is reset, and each hardware unit is initialized (reset).
During the reset period, oscillation of the main system clock is unconditionally stopped. Consequently, the current
consumption of the entire system can be reduced.
When the RESET signal goes high, the reset status is cleared, oscillation stabilization time (41.9 ms at 12.5 MHz)
elapses, the contents of the reset vector table are set to the program counter (PC), execution branches to an address
set to the PC, and program execution is started from that branch address. Therefore, the program can be reset
and started from any address.
Figure 11-1. Oscillation of Main System Clock during Reset Period
Main system clock
oscillator
fCLK
Oscillation is unconditionally
stopped during rest period
RESET input
Oscillation stabilization time
The RESET input pin has an analog delay noise eliminator to prevent malfunctioning due to noise.
Figure 11-2. Accepting Reset Signal
Analog delay
Analog delay
Analog
delay
Time until the clock starts oscillation
Oscillation
stabilization
time
RESET input
Internal reset signal
Internal clock
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Data Sheet U12376EJ1V0DS00