M306H7MG-XXXFP Datasheet, PDF (13/329 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with DATA ACQUISITION CONTROLLER

M306H7MG-XXXFP/MC-XXXFP/FGFP
3. RESET
3. Reset
There are three types of resets: a hardware reset, a software reset, and a watchdog timer reset.
3.1 Hardware Reset
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 3.1).
The oscillation circuit is initialized and the main clock starts oscillating. 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. The internal RAM is not initialized. If the RESET pin is pulled “L” while writing to
the internal RAM, the internal RAM becomes indeterminate.
Figure 3.1 shows the example reset circuit. Figure 3.2 shows the reset sequence. Table 3.1 shows the statuses of the
other pins while the RESET pin is “L”. Figure 3.3 shows the CPU register status after reset.
Refer to “SFR” for SFR status after reset.
1. When the power supply is stable
• When STARTB pin = “L”
(1) Apply an “L” signal to the RESET pin.
(2) Apply a clock for 20 cycles or more to the XIN pin.
(3) Apply an “H” signal to the RESET pin.
• When STARTB pin = “H”
(1) Apply an “L” signal to the RESET pin.
(2) Apply a clock for 20 cycles or more to the XCIN pin.
(3) Apply an “H” signal to the RESET pin.
2. Power on
• When STARTB pin = “L”
(1) Apply an “L” signal to the RESET pin.
(2) Let the power supply voltage increase until it meets the recommended operating condition.
(3) Wait td(P-R) or more until the internal power supply is stabilized.
(4) Apply a clock for 20 cycles or more to the XIN pin.
(5) Apply an “H” signal to the RESET pin.
• When STARTB pin = “H”
(1) Apply an “L” signal to the RESET pin.
(2) Let the power supply voltage increase until it meets the recommended operating condition.
(3) Wait td(P-R) or more until the internal power supply is stabilized.
(4) Apply a clock for 20 cycles or more to the XCIN pin.
(5) Apply an “H” signal to the RESET pin.
Rev.2.10 Oct 25, 2006 Page 13 of 326
REJ03B0152-0210