R8C/13 Group
5.1 Hardware Reset
5.1.2 Hardware Reset 2
This is the reset generated by the voltage detection circuit which is built-in to the microcomputer. The
voltage detection circuit monitors the input voltage at Vcc input pin. The microcomputer is reset when
the voltage at the VCC input pin drops below Vdet if all of the following conditions hold true.
• The VC27 bit in the VCR2 register is set to “1” (voltage detection circuit enabled)
• The D40 bit in the D4INT register is set to “1” (voltage detection interrupt enabled)
• The D46 bit in the D4INT register is set to “1” (hardware reset 2 when going through Vdet)
When using a digital filter (D41 bit in the D4INT register is set to “1”), set the CM14 bit in the CM1
register to “0”(low-speed on-chip oscillator oscillates).
Conversely, when the input voltage at the VCC pin rises to Vdet or more, the pins, CPU, and SFR are
initialized and counting the low-speed on-chip oscillator starts. When counting the low-speed on-chip
oscillator clock 32 times, the internal reset is exited and the program is executed beginning with the
address indicated by the reset vector. The initialized pins and registers and the status thereof are the
same as in hardware reset 1. Refer to Section 5.4 “Voltage Detection Circuit.”
Rev.1.20 Jan 27, 2006 page 17 of 205
REJ09B0111-0120
RENESAS [ RENESAS TECHNOLOGY CORP ]
