Filter
Top Products
- 34 -
3.7 Stacks
3.7.1 System Stack and User Stack
The MR100 provides two types of stacks: system stack and user stack.
• User Stack
One user stack is provided for each task. Therefore, when writing applications with the MR100, it is necessary to
furnish the stack area for each task.
• System Stack
This stack is used within the MR100 (during service call processing). When a service call is issued from a task,
the MR100 switches the stack from the user stack to the system stack (See Figure 3.25).
The system
stack use the interrupt stack(ISP).
Task MR100 service call processing
User Stack
User Stack
System Stack
Save Registers
Stack switching
Service call
processing
Task sel ec tion
Stack switching
Restore Registers
XXX_XXX( )
Figure 3.25 System Stack and User Stack
Switchover from user stack to system stack occurs when an interrupt of vector numbers 0 to 127 is generated. Consequently,
all stacks used by the interrupt handler are the system stack.