M16C6NK Datasheet, PDF (53/404 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

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M16C/6N Group (M16C/6NK, M16C/6NM)
5. Reset
5. Reset
Hardware reset, software reset, watchdog timer reset and oscillation stop detection reset are available to
reset the microcomputer.
5.1 Hardware Reset
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The microcomputer resets pins, the CPU and SFR by setting the RESET pin. If the supply voltage meets
the recommended operating conditions, the microcomputer resets all pins when an “L” signal is applied to
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the RESET pin (see Table 5.1 Pin Status When RESET Pin Level is “L”). The oscillation circuit is also
reset and the main clock starts oscillation. The microcomputer resets the CPU and SFR when the signal
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applied to the RESET pin changes low (“L”) to high (“H”). The microcomputer executes the program in an
address indicated by the reset vector. The internal RAM is not reset. When an “L” signal is applied to the
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RESET pin while writing data to the internal RAM, the internal RAM is in an indeterminate state.
Figure 5.1 shows an example of the reset circuit. Figure 5.2 shows a reset sequence. Table 5.1 lists pin
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states while the RESET pin is held low (“L”).
5.1.1 Reset on a Stable Supply Voltage
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(1) Apply “L” to the RESET pin
(2) Apply 20 or more clock cycles to the XIN pin
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(3) Apply “H” to the RESET pin
5.1.2 Power-on Reset
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(1) Apply “L” to the RESET pin
(2) Raise the supply voltage to the recommended operating level
(3) Insert td(P-R) ms as wait time for the internal voltage to stabilize
(4) Apply 20 or more clock cycles to the XIN pin
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(5) Apply “H” to the RESET pin
VCC
Recommended
operation
voltage
0V
RESET
VCC
RESET
0V
0.2VCC or
below
NOTE
1. Use the shortest possible wiring to connect external circuit.
0.2VCC or below
Supply a clock with td(P-R) +20
or more cycles to the XIN pin
Figure 5.1 Example Reset Circuit
Rev.2.00 Nov 28, 2005 page 35 of 378
REJ09B0124-0200