M16C6S_09 Datasheet, PDF (19/208 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6S Group
Reset
Reset
There are four types of resets: a hardware reset, a software reset, an watchdog timer reset, and an oscilla-
tion stop detection reset.
Hardware Reset
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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 1.5.1). The oscillation circuit is initialized and the main clock starts oscillating. When the input
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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.
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If the RESET pin is pulled “L” while writing to the internal RAM, the internal RAM becomes indetermi-
nate.
Figure 1.5.1 shows the example reset circuit. Figure 1.5.2 shows the reset sequence. Table 1.5.1
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shows the statuses of the other pins while the RESET pin is “L”. Figure 1.5.3 shows the CPU register
status after reset. Refer to “SFR” for SFR status after reset.
1. When the power supply is stable
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(1) Apply an “L” signal to the RESET pin.
(2) Supply a clock for 20 cycles or more to the XIN pin.
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(3) Apply an “H” signal to the RESET pin.
2. Power on
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(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 stabilizes.
(4) Supply a clock for 20 cycles or more to the XIN pin.
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(5) Apply an “H” signal to the RESET pin.
Rev.5.01 Dec 10, 2009 page 19 of 201
REJ03B0014-0501