[RX850V4] Task

What is a task stack?

A task stack is used by task functions of the RX850, RX850Pro, and RX850V4.

The task stack is an area provided for saving information to be used by task functions. It is also used to save the current register information upon task suspension, so that the register information can be restored when the task is resumed.

The task stack area is located in the RAM area, and its size is specified by the system configuration file when a task is generated.

Since the RX850 V3.2x and later, RX850Pro V3.2x and later, and RX850V4 automatically secure the area for saving register information, the user should specify only the size of the area for saving information to be used by task functions.

The RX850 V3.1x and earlier and RX850Pro V3.1x and earlier, however, do not secure the area for saving register information automatically. When generating a task with the system configuration file, therefore, the user should also specify the size of this area, in addition to that of the area for saving information to be used by task functions.

If the stack area runs short, problems such as damage to other RAM areas and malfunction may occur.
If an application using a real-time OS is not operating correctly, 80% of time the cause is insufficient task stack capacity.