SAM9XE256 Atmel Corporation, SAM9XE256 Datasheet - Page 49

• Manufacturer Part Number: SAM9XE256
• Manufacturer: Atmel Corporation

Specifications of SAM9XE256

• Flash (kbytes): 256 Kbytes
• Pin Count: 217
• Max. Operating Frequency: 180 MHz
• Cpu: ARM926
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 96
• Ext Interrupts: 96
• Usb Transceiver: 3
• Usb Speed: Full Speed
• Usb Interface: Host, Device
• Spi: 2
• Twi (i2c): 2
• Uart: 6
• Ssc: 1
• Ethernet: 1
• Sd / Emmc: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: Yes
• Adc Channels: 4
• Adc Resolution (bits): 10
• Adc Speed (ksps): 312
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 32
• Self Program Memory: NO
• External Bus Interface: 1
• Dram Memory: sdram
• Nand Interface: Yes
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8/3.3
• Operating Voltage (vcc): 1.65 to 1.95
• Fpu: No
• Mpu / Mmu: No / Yes
• Timers: 6
• Output Compare Channels: 6
• Input Capture Channels: 6
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: No

11.3.7.2
11.3.7.3
11.3.7.4
6254C–ATARM–22-Jan-10
Exceptions
Exception Types and Priorities
Exception Modes and Handling
The
leged mode. The types of exceptions are:
When an exception occurs, the banked version of R14 and the SPSR for the exception mode
are used to save the state.
More than one exception can happen at a time, therefore the ARM9EJ-S takes the arisen excep-
tions according to the following priority order:
The BKPT, or Undefined instruction, and SWI exceptions are mutually exclusive.
Note that there is one exception in the priority scheme: when FIQs are enabled and a Data Abort
occurs at the same time as an FIQ, the ARM9EJ-S core enters the Data Abort handler, and pro-
ceeds immediately to FIQ vector. A normal return from the FIQ causes the Data Abort handler to
resume execution. Data Aborts must have higher priority than FIQs to ensure that the transfer
error does not escape detection.
Exceptions arise whenever the normal flow of a program must be halted temporarily, for exam-
ple, to service an interrupt from a peripheral.
When handling an ARM exception, the ARM9EJ-S core performs the following operations:
• The Sticky Overflow (Q) flag can be set by certain multiply and fractional arithmetic
• The J bit in the CPSR indicates when the ARM9EJ-S core is in Jazelle state, where:
• Mode: five bits to encode the current processor mode
• Fast interrupt (FIQ)
• Normal interrupt (IRQ)
• Data and Prefetched aborts (Abort)
• Undefined instruction (Undefined)
• Software interrupt and Reset (Supervisor)
• Reset (highest priority)
• Data Abort
• FIQ
• IRQ
• Prefetch Abort
• BKPT, Undefined instruction, and Software Interrupt (SWI) (Lowest priority)
instructions like QADD, QDADD, QSUB, QDSUB, SMLAxy, and SMLAWy needed to achieve
DSP operations.
The Q flag is sticky in that, when set by an instruction, it remains set until explicitly cleared by
an MSR instruction writing to the CPSR. Instructions cannot execute conditionally on the
status of the Q flag.
ARM9EJ-S supports five types of exceptions. Each type drives the ARM9EJ-S in a privi-
– J = 0: The processor is in ARM or Thumb state, depending on the T bit
– J = 1: The processor is in Jazelle state.
AT91SAM9XE128/256/512 Preliminary
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