HD6417618 datasheet(80/646 Pages) RENESAS

80 / 646 page

Section 2 CPU

Rev. 6.00 Jun. 12, 2007 Page 48 of 610

REJ09B0131-0600

• Reset state

The CPU is reset. When the

RES pin is driven low, the CPU enters the power-on reset state.

When the

RES pin is high and MRES pin is low, the CPU enters the manual reset state.

• Exception handling state

This state is a transitional state in which the CPU processing state changes due to a request for

exception handling such as a reset or an interrupt.

When a reset occurs, the execution start address as the initial value of the program counter

(PC) and the initial value of the stack pointer (SP) are fetched from the exception handling

vector table. Then, a branch is made for the start address to execute a program.

When an interrupt occurs, the PC and status register (SR) are saved in the stack area pointed to

by SP. The start address of an exception handling routine is fetched from the exception

handling vector table and a branch to the address is made to execute a program.

Then the processing state enters the program execution state.

• Program execution state

The CPU executes programs sequentially.

• Power-down state

The CPU stops to reduce power consumption. The SLEEP instruction makes the CPU enter

sleep mode or software standby mode.

HD6417618 Datasheet(PDF) 80 Page - Renesas Technology Corp