Datasheet

Section 4 Exception Handling
R01UH0309EJ0500 Rev. 5.00 Page 103 of 1408
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
4.4 Trace Exception Handling
Traces are enabled in interrupt control mode 2. Trace mode is not activated in interrupt control
mode 0, irrespective of the state of the T bit. For details on interrupt control modes, see section 5,
Interrupt Controller.
If the T bit in EXR is set to 1, trace mode is activated. In trace mode, a trace exception occurs on
completion of each instruction. Trace mode is not affected by interrupt masking. Table 4.3 shows
the state of CCR and EXR after execution of trace exception handling. Trace mode is canceled by
clearing the T bit in EXR to 0. The T bit saved on the stack retains its value of 1, and when control
is returned from the trace exception handling routine by the RTE instruction, trace mode resumes.
Trace exception handling is not carried out after execution of the RTE instruction.
Interrupts are accepted even within the trace exception handling routine.
Table 4.3 Status of CCR and EXR after Trace Exception Handling
CCR EXR
Interrupt Control Mode I UI I2 to I0 T
0 Trace exception handling cannot be used.
2 1 ⎯ ⎯ 0
[Legend]
1: Set to 1
0: Cleared to 0
⎯: Retains value prior to execution