M1AFS-EMBEDDED-KIT Actel, M1AFS-EMBEDDED-KIT Datasheet - Page 23

• Manufacturer Part Number: M1AFS-EMBEDDED-KIT
• Description: MCU, MPU & DSP Development Tools CortexM1-enabled Fusion Embedded Kit
• Manufacturer: Actel

Specifications of M1AFS-EMBEDDED-KIT

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Servicing an Exception
When the processor invokes an exception, it automatically pushes the following eight registers in two
stages to the stack in the following order:
The SP is decremented by eight words on the completion of the stack
contents of the stack after an exception preempts the current program flow.
Figure 3-3 • Stack Contents from an Exception
When the processor services an exception, it takes the following steps before it enters the exception
service routine.
1. Processor Status Register (xPSR)
2. ReturnAddress ()
3. Link Register (LR)
4. R12
5. R3
6. R2
7. R1
8. R0
1. It pushes 8 registers: xPSR, ReturnAddress (), R0, R1, R2, R3, R12, and LR on the selected
2. It reads the vector from the appropriate vector table entry, for example: (0x0) +
3. On Reset only, SP_main is updated from the first entry in the vector table. Other exceptions do
4. Updates PC with vector table read location. No other late-arriving exceptions can be processed
5. LR is set to EXC_RETURN to exit from the exception.
stack
(exception_number *4). This vector table read is done after all eight registers in the previous step
are pushed onto the stack.
not modify SP_main at this time and in this manner.
until the first instruction of the exception starts to execute.
Old SP
SP
R ev i si o n 1 2
ReturnAddress ()
<previous>
xPSR
R12
R3
R2
R1
LR
R0
push.Figure 3-3
Cortex-M1 v3.1 Handbook
shows the
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