Datasheet

74
SAM4S Series [DATASHEET]
11100F–ATARM–29-Jan-14
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” .
For more information about hard faults, memory management faults, bus faults, and usage faults, see “Fault Handling” .
12.4.3.3 Exception Handlers
The processor handles exceptions using:
 Interrupt Service Routines (ISRs)
Interrupts IRQ0 to IRQ34 are the exceptions handled by ISRs.
 Fault Handlers
Hard fault, memory management fault, usage fault, bus fault are fault exceptions handled by the fault handlers.
 System Handlers
NMI, PendSV, SVCall SysTick, and the fault exceptions are all system exceptions that are handled by system
handlers.
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