HD6417751RBP240V Datasheet, PDF (247/1226 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

5. Exceptions
5.6.1 Resets
(1) Power-On Reset
• Sources:
⎯ RESET pin low level
⎯ When the watchdog timer overflows while the WT/IT bit is set to 1 and the RSTS bit is
cleared to 0 in WTCSR. For details, see section 10, Clock Oscillation Circuits.
• Transition address: H'A000 0000
• Transition operations:
Exception code H'000 is set in EXPEVT, initialization of VBR and SR is performed, and a
branch is made to PC = H'A000 0000.
In the initialization processing, the VBR register is set to H'0000 0000, and in SR, the MD,
RB, and BL bits are set to 1, the FD bit is cleared to 0, and the interrupt mask bits (IMASK)
are set to B'1111.
CPU and on-chip peripheral module initialization is performed. For details, see the register
descriptions in the relevant sections. For some CPU functions, the TRST pin and RESET pin
must be driven low. It is therefore essential to execute a power-on reset and drive the TRST
pin low when powering on.
If the RESET pin is driven high before the MRESET pin while both these pins are low, a
manual reset may occur after the power-on reset operation. The RESET pin must be driven
high at the same time as, or after, the MRESET pin.
Power_on_reset()
{
EXPEVT = H'00000000;
VBR = H'00000000;
SR.MD = 1;
SR.RB = 1;
SR.BL = 1;
SR.IMASK = B'1111;
SR.FD=0;
Initialize_CPU();
Initialize_Module(PowerOn);
PC = H'A0000000;
}
Rev.4.00 Oct. 10, 2008 Page 147 of 1122
REJ09B0370-0400