Atmel SAM4S-EK2 Atmel ATSAM4S-EK2 ATSAM4S-EK2 Data Sheet

Product codes

ATSAM4S-EK2

SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13



An illegal unaligned access



An invalid state on instruction execution



An error on exception return.

The following can cause a Usage Fault when the core is configured to report them:



An unaligned address on word and halfword memory access



A division by zero.

SVCall

A supervisor call (SVC) is an exception that is triggered by the SVC instruction. In an OS environment, applications can
use SVC instructions to access OS kernel functions and device drivers.

PendSV

PendSV is an interrupt-driven request for system-level service. In an OS environment, use PendSV for context switching
when no other exception is active.

SysTick

A SysTick exception is an exception the system timer generates when it reaches zero. Software can also generate a
SysTick exception. In an OS environment, the processor can use this exception as system tick.

Interrupt (IRQ)

A interrupt, or IRQ, is an exception signalled by a peripheral, or generated by a software request. All interrupts are
asynchronous to instruction execution. In the system, peripherals use interrupts to communicate with the processor.

Notes: 1. To simplify the software layer, the CMSIS only uses IRQ numbers and therefore uses negative values for exceptions

other than interrupts. The IPSR returns the Exception number, see

“Interrupt Program Status Register”

2. See

“Vector Table”

for more information

3. See

“System Handler Priority Registers”

4. See

“Interrupt Priority Registers”

5. Increasing in steps of 4.

Table 12-9. Properties of the Different Exception Types