Datasheet

SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
70
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.
For an asynchronous exception, other than reset, the processor can execute another instruction between when the
exception is triggered and when the processor enters the exception handler.
Privileged software can disable the exceptions that Table 12-9 shows as having configurable priority, see:
 “System Handler Control and State Register”
 “Interrupt Clear-enable Registers” .
Table 12-9. Properties of the Different Exception Types
Exception
Number
(1)
Irq Number
(1)
Exception Type Priority
Vector Address
or Offset
(2)
Activation
1 – Reset -3, the highest 0x00000004 Asynchronous
2 -14 NMI -2 0x00000008 Asynchronous
3 -13 Hard fault -1 0x0000000C –
4 -12
Memory
management fault
Configurable
(3)
0x00000010 Synchronous
5 -11 Bus fault Configurable
(3)
0x00000014
Synchronous when precise,
asynchronous when imprecise
6 -10 Usage fault Configurable
(3)
0x00000018 Synchronous
7–10 – – – Reserved –
11 -5 SVCall Configurable
(3)
0x0000002C Synchronous
12–13 – – – Reserved –
14 -2 PendSV Configurable
(3)
0x00000038 Asynchronous
15 -1 SysTick Configurable
(3)
0x0000003C Asynchronous
16 and above 0 and above Interrupt (IRQ) Configurable
(4)
0x00000040 and above
(5)
Asynchronous