R01US0079ED0103 Datasheet, PDF (61/66 Pages) Renesas Technology Corp – RENESAS 32-Bit MCU

Data Flash Access Library - Type T01, European Release
Library Setup and Usage
Error treatment of the FDL functions themselves is not detailed described in the flow charts for
simplification reasons.
For details on enabling or disabling access to the Data Flash, refer to the user's manual for the hardware.
An example is given by the sample application, file sample_app_main.c, functions FDL_Open and
FDL_Close.
5.8 R_FDL_Handler calls
Once initiated FDL operations need to be driven forward by successive handler calls. The frequency of
these handler calls does have an impact on the FDL operation performance and needs to be adapted to
the target application.
In the following, different approaches for calling the R_FDL_Handler are compared with respect to their
advantages and disadvantages:
 Calling R_FDL_Handler repeatedly after starting an operation execution: This approach is also
utilized in most of the code examples you can find in this manual. Typically realized in a loop waiting
for the operation status not to be busy anymore, this approach results in the best FDL operation
performance. However, the CPU is fully loaded and blocked for other tasks as long as the FDL
operation is being executed.
 Calling R_FDL_Handler in a timed task: By calling the R_FDL_Handler periodically, FDL
commands can be driven forward while other tasks are processed by the CPU. The period between
the status check calls can have significant impact on the FDL operation performance. Shorter calling
intervals result in better FDL performance, but also increase the CPU load by the FDL. Due to this
trade off, a general advice for the calling interval cannot be given. It needs to be analysed and tailored
individually for each target application.
 Calling R_FDL_Handler in the idle task: If it is ensured that the idle task is called often enough, this
method might result in a good FDL performance, as the handler can be called continuously. However,
this approach is not deterministic in case of a high CPU load by the application itself.
Due to the individual requirements of each application, a general advice for selecting a strategy to call the
R_FDL_Handler cannot be given. Please also consider that mixtures of the above mentioned
approaches can be meaningful depending on the target scenario.
Note:
When evaluating concepts for calling the R_FDL_Handler, please be aware that all FDL functions are
not re-entrant. That means it is not allowed to call an FDL function from interrupt service routines while
another FDL function is already running.
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User Manual