D12320VF25IV Datasheet, PDF (133/1304 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 4 Exception Handling
Section 4 Exception Handling
4.1 Overview
4.1.1 Exception Handling Types and Priority
As table 4.1 indicates, exception handling may be caused by a reset, trap instruction, or interrupt.
Exception handling is prioritized as shown in table 4.1. If two or more exceptions occur
simultaneously, they are accepted and processed in order of priority. Trap instruction exceptions
are accepted at all times in the program execution state.
Exception handling sources, the stack structure, and the operation of the CPU vary depending on
the interrupt control mode set by the INTM0 and INTM1 bits of SYSCR.
Table 4.1 Exception Types and Priority
Priority Exception Type
Start of Exception Handling
High
Reset
Trace^*1
Starts immediately after a low-to-high transition at the
RES pin, or when the watchdog timer overflows.
Starts when execution of the current instruction or
exception handling ends, if the trace (T) bit is set to 1
Interrupt
Starts when execution of the current instruction or
exception handling ends, if an interrupt request has been
issued^*2
Low
Trap instruction (TRAPA) ^*3 Started by execution of a trap instruction (TRAPA)
Notes: 1. Traces are enabled only in interrupt control mode 2. Trace exception handling is not
executed after execution of an RTE instruction.
2. Interrupt detection is not performed on completion of ANDC, ORC, XORC, or LDC
instruction execution, or on completion of reset exception handling.
3. Trap instruction exception handling requests are accepted at all times in the program
execution state.
Rev.6.00 Sep. 27, 2007 Page 101 of 1268
REJ09B0220-0600