M32C80 Datasheet, PDF (49/352 Pages) Renesas Technology Corp – 16/32-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M32C/80 SERIES

M32C/80 Group
5. Reset
5. Reset
Hardware reset 1, software reset, and watchdog timer reset are available to reset the microcomputer.
5.1 Hardware Reset 1
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Pins, the CPU and SFRs are reset by setting the RESET pin. If the supply voltage meets the recommended
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operating conditions, all pins are reset when a low-level ("L") signal is applied to the RESET pin (see Table
5.1). The oscillation circuit is also reset and the main clock starts oscillating. The CPU and SFR are reset
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when the signal applied to the RESET pin changes "L" to high level ("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
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applied to the 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 "L".
5.1.1 Reset on a Stable Supply Voltage
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(1) Apply an "L" signal to the RESET pin
(2) Provide 20 or more clock cycle inputs into the XIN pin
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(3) Apply an "H" signal to the RESET pin
5.1.2 Power-on Reset
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(1) Apply an "L" signal 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) Provide 20 or more clock cycle inputs into the XIN pin
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(5) Apply an "H" signal to the RESET pin
Recommended
operating voltage
VCC1
RESET
VCC1
0V
RESET
0V
0.2VCC1
or below
0.2VCC1 or below
td(P-R) + 20 or more clock cycle
inputs provided into the XIN pin
NOTE:
1. If VCC1>VCC2, the VCC2 voltage must be lower than that of VCC1 when the power is
being turned on or off.
Figure 5.1 Reset Circuit
Rev. 1.00 Nov. 01, 2005 Page 30 of 330
REJ09B0271-0100