SH7261 datasheet(130/1348 Pages) RENESAS

130 / 1348 page

Section 5 Exception Handling

Rev. 2.00 Sep. 07, 2007 Page 98 of 1312

REJ09B0320-0200

When exception handling starts, the CPU operates as follows:

(1)

Exception Handling Triggered by Reset

The initial values of the program counter (PC) and stack pointer (SP) are fetched from the

exception handling vector table (PC and SP are respectively the H'00000000 and H'00000004

addresses for power-on resets and the H'00000008 and H'0000000C addresses for manual resets).

See section 5.1.3, Exception Handling Vector Table, for more information. The vector base

status register (SR) are initialized to H'F (B'1111), and the BO and CS bits are initialized. The BN

bit in IBNR of the interrupt controller (INTC) is also initialized to 0. FPSCR is initialized to

H'00040001 by a power-on reset. The program begins running from the PC address fetched from

the exception handling vector table.

(2)

Exception Handling Triggered by Address Errors, Bus Errors, Register Bank Errors,

Interrupts, and Instructions

SR and PC are saved to the stack indicated by R15. In the case of interrupt exception handling

other than the NMI or user break, with usage of the register banks enabled, general registers R0 to

R14, control register GBR, system registers MACH, MACL, and PR, and the vector number of the

interrupt exception handling to be executed are saved to the register banks. In the case of

exception handling due to an address error, bus error, register bank error, NMI interrupt, user

break interrupt, or instruction, saving to a register bank is not performed. When saving is

performed to all register banks, automatic saving to the stack is performed instead of register bank

saving. In this case, an interrupt controller setting must have been made so that register bank

overflow exceptions are not accepted (the BOVE bit in IBNR of the INTC is 0). If a setting to

accept register bank overflow exceptions has been made (the BOVE bit in IBNR of the INTC is

1), register bank overflow exception will be generated. In the case of interrupt exception handling,

the interrupt priority level is written to the I3 to I0 bits in SR. In the case of exception handling

due to an address error or instruction, the I3 to I0 bits are not affected. The start address is then

fetched from the exception handling vector table and the program begins running from that

address.

SH7261 Datasheet(PDF) 130 Page - Renesas Technology Corp