M16C65 Datasheet, PDF (103/829 Pages) Renesas Technology Corp – RENESAS MCU M16C FAMILY / M16C/60

Under development
M16C/65 Group
Preliminary Specification
This is a preliminary specification and is subject to change.
6. Resets
6.4.2 Hardware Reset
This reset is triggered by the RESET pin. If the power supply voltage meets the recommended
operating conditions, the MCU resets the pins, CPU, and SFRs when a low-level signal is applied to the
RESET pin.
When the signal applied to the RESET pin changes from low to high, the MCU executes the program at
the address indicated by the reset vector. The fOCO-S divided by 8 is automatically selected as the
CPU clock after reset.
The HWR bit in the RSTFR register becomes 1 (hardware reset detected) after hardware reset. Refer
to 4. “Special Function Registers (SFRs)” for the rest of the SFR states after reset.
The internal RAM is not reset. When a low-level signal is applied to the RESET pin while writing data to
the internal RAM, the internal RAM is in an undefined state.
The procedures for generating a hardware reset are as follows:
When Power Supply is Stable
(1) Apply a low-level signal to the RESET pin.
(2) Wait for f(OCOS).
(3) Apply a high-level signal to the RESET pin.
When Power is Turned on
(4) Apply a low-level signal to the RESET pin.
(5) Raise the power supply voltage to the recommended operating level.
(6) Wait for td(P-R) until the internal voltage stabilizes.
(7) Wait for f(OCOS).
(8) Apply a high-level signal to the RESET pin.
Figure 6.4 shows an Example Reset Circuit.
RESET
VCC1
Recommended
VCC1
operating
voltage
0V
RESET
0.2 VCC1 or below
0V
0.2 VCC1 or below
td(P-R) + f(OCOS) or above
Note :
1. If VCC1 > VCC2, make sure that the VCC2 voltage is lower than that of VCC1 when the power is turned
on or off.
Figure 6.4 Example Reset Circuit
REJ09B0484-0030 Rev.0.30 Sep 09, 2008
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