Hardware Reset - Renesas M16C/64A Series User Manual

M16C/64A Group
6.4.2

Hardware Reset

This reset is triggered by the RESET pin. When 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 changing the signal applied to the RESET pin from low to high, the MCU executes the program
at the address indicated by the reset vector. 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 remaining 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 becomes undefined.
The procedures for generating a hardware reset are as follows:
When the power supply is stable
(1) Apply a low-level signal to the RESET pin.
(2) Wait for tw(RSTL).
(3) Apply a high-level signal to the RESET pin.
When the power is turned on
(1) Apply a low-level signal to the RESET pin.
(2) Raise the power supply voltage to the recommended operating level.
(3) Wait for td(P-R) until the internal voltage stabilizes.
(4) Wait for
--------------------- -
fOCO S –
(5) Apply a high-level signal to the RESET pin.
Figure 6.4 shows an Reset Circuit Example.
VCC1
RESET
Note:
1. When 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 Reset Circuit Example
R01UH0136EJ0210 Rev.2.10
Jul 31, 2012
1
× 20 cycles.
Recommended
operating
VCC1
voltage
0 V
RESET
0.2 VCC1 or below
0 V
0.2 VCC1 or below
1
× 20 cycles or above
td(P-R) +
fOCO-S
6. Resets
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