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Manual Configuration
Each section of this manual consists of a title, summary, main text, key information, precautions and warnings, and
references.
The layout and definition of each section are shown below.
Subtitle
Sub-subtitle
The smallest block
in this manual.
Chapter 2 Basic CPU
2-8
2-8-1
Reset
Summary
Reset operation
Introduction to the
section.
Main text
The CPU contents are reset and registers are initialized when the NRST pin (P.27) is pulled to low.
Initiating a Reset
There are two methods to initiate a reset.
(1)
Drive the NRST pin low for at least four clock cycles.
NRST pin should be holded "low" for more than 4 clock cycles (200 nS at a 20 MHz).
NRST pin
4 clock cycles
(200 nS at a 20 MHz)
Figure 2-8-1
(2)
Minimum Reset Pulse Width
Setting the P2OUT7 flag of the P2OUT register to "0" outputs low level at P27 (NRST) pin. And
transfering to reset by program (software reset) can be executed. If the internal LSI is reset and
register is initiated, the P2OUT7 flag becomes "1" and reset is released.
[
Chapter 4. 4-4-2 Registers ]
References
References for the
main text.
Key information
Important information
from the text.
On this LSI, the starting mode is NORMAL mode that high oscillation is the base clock.
When the power voltage low circuit is connected to NRST pin, circuit that gives pulse for
enough low level time at sudeen unconnected. And reset can be generated even if its pulse
is low level as the oscillation clock is under 4 clocks, take notice of noise.
Precautions and
warnings
Precautions are listed
in case.
Be sure to read these
of lost functionality or
damage.
II - 44
Reset
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