E2, IE850A
5. Notes on Usage
R20UT4140EJ0300 Rev.3.00
Page 30 of 41
Oct.09.20
5.4.8
The order of event detection
In the following cases, since the orders of instructions and event detection may not operate as set, to measure
the time or performance in sequential events, section tracing, and desired sections may not be possible.
•
Adjacent read and write instructions may be detected as a single access event since multiple instructions
are executed at the same time and the timing of event detection differs in write and read access events
which are set for consecutive instructions. The timing may be detected in the order of reading then writing,
even though the instructions are executed in the order of writing then reading.
•
Access events may be detected at the same time since local RAM and cluster RAM can be accessed
simultaneously and up to four access events are detectable.
5.4.9
Access trace function
The following restrictions apply to access to trace data.
•
When tracing is performed with an access-type point or a range event, data comparison conditions are
always ignored regardless of whether or not such conditions have been set and access in which any
condition except for a data comparison condition is detected is traced.
•
In case of access to data by the FXU instruction, the data cannot be traced.
•
Write access which has been suppressed in response to an STC instruction failing and read/write access
which has been suppressed in response to the inhibition of MDP exceptions may not be traced.
5.4.10 Losing trace information
In some cases, acquired trace information will be lost (trace overflow). This depends on the program being
executed. The lost information cannot be restored, but the fact of the loss is indicated (displayed).
5.4.11 Recording trace memory during non-realtime tracing
When trace data are stored in internal trace memory and priority in tracing is not given to realtime operation,
the functions to stop tracing when the trace memory becomes full (trace-full stop function) and when a
specified number of trace messages have been acquired following an event (trace delay-stop function) are not
available. To use these functions, give priority to realtime operation.
5.4.12 Performance measurement
In the case of measuring a specific section, if the intervals between the start and the end of one measurement,
and between the end of that measurement and the start of the next is short, the measurement is not possible.
To obtain correct measurements, the interval* should be long enough.
*: The required detection interval depends on the operating frequency and the LPD communications frequency
of the MCU.
5.4.13 Stepped execution of the HALT mode and the HALT instruction
A break leads to release from HALT mode.
When a HALT instruction is encountered during single step execution (execution in units of assembly
instruction), a break is set at the next instruction following the HALT instruction, and the mode does not
change to the HALT mode. When a HALT instruction is encountered during C-source-level stepped execution,
whether or not the transition to the HALT mode proceeds depends on the facilities of the debugger.
