R8C/13 Group
5.1 Hardware Reset
5. Reset
There are three types of resets: a hardware reset, a software reset, and an watchdog timer reset.
5.1 Hardware Reset
There are three kinds of hardware reset: hardware reset 1, hardware reset 2, and power-on reset.
After reset, the low-speed on-chip oscillator clock divided by 8 is automatically selected for the CPU.
5.1.1 Hardware Reset 1
____________
____________
A reset is applied using the RESET pin. When an “L” signal is applied to the RESET pin while the
power supply voltage is within the recommended operating condition, the pins are initialized (see
____________
____________
Table 5.1 “Pin Status When RESET Pin Level is 'L'”). When the input level at the RESET pin is
released from “L” to “H”, the CPU and SFR are initialized, and the program is executed starting
from the address indicated by the reset vector. Figure 5.1 shows the CPU register status after
____________
reset and figure 5.2 shows the reset sequence. The internal RAM is not initialized. If the RESET
pin is pulled “L” while writing to the internal RAM, the internal RAM becomes indeterminate.
Figures 5.3 to 5.4 show the reset circuit example using the hardware reset 1. Refer to Chapter 4,
“Special Function Register (SFR)” for the status of SFR after reset.
• When the power supply is stable
____________
(1) Apply an “L” signal to the RESET pin.
(2) Wait for 500 µs (1/fRING-S ✕ 20).
____________
(3) Apply an “H” signal to the RESET pin.
• Power on
____________
(1) Apply an “L” signal to the RESET pin.
(2) Let the power supply voltage increase until it meets the recommended operating condi-
tion.
(3) Wait td(P-R) or more until the internal power supply stabilizes.
(4) Wait for 500 µs (1/fRING-S ✕ 20).
____________
(5) Apply an “H” signal to the RESET pin.
____________
Table 5.1 Pin Status When RESET Pin Level is “L”
Pin name
Pin status
P0
P1
Input port
Input port
Input port
Input port
P30 to P33, P37
P45 to P4
7
Rev.1.20 Jan 27, 2006 page 14 of 205
REJ09B0111-0120
RENESAS [ RENESAS TECHNOLOGY CORP ]
