AT91SAM9G45-EKES Atmel, AT91SAM9G45-EKES Datasheet - Page 37

• Manufacturer Part Number: AT91SAM9G45-EKES
• Description: KIT EVAL FOR AT91SAM9G45
• Manufacturer: Atmel
• Series: AT91SAM Smart ARMr
• Type: MCUr

Specifications of AT91SAM9G45-EKES

• Contents: Board
• Processor To Be Evaluated: SAM9G45
• Data Bus Width: 32 bit
• Interface Type: I2C, SPI, UART
• Maximum Operating Temperature: + 50 C
• Minimum Operating Temperature: - 10 C
• Operating Supply Voltage: 1.8 V to 3.3 V
• For Use With/related Products: AT91SAM9G45
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: Q4626953

9.4.7.1
9.4.7.2
9.4.7.3
6438F–ATARM–21-Jun-10
Status Registers
Exceptions
Exception Types and Priorities
There are banked registers SPs, LRs and SPSRs for each privileged mode (for more details see
the ARM9EJ-S Technical Reference Manual, revision r1p2 page 2-12).
The ARM9EJ-S core contains one CPSR, and five SPSRs for exception handlers to use. The
program status registers:
Figure 9-2.
Figure 9-2
The
leged mode. The types of exceptions are:
• CPSR
• hold information about the most recently performed ALU operation
• control the enabling and disabling of interrupts
• set the processor operation mode
• N: Negative, Z: Zero, C: Carry, and V: Overflow are the four ALU flags
• 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)
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.
shows the status register format, where:
Status Register Format
N Z C V Q
31 30 29 28 27
24
J
Jazelle state bit
Reserved
Sticky Overflow
Overflow
Carry/Borrow/Extend
Zero
Negative/Less than
Reserved
I F T
7 6 5
Mode
0
Mode bits
Thumb state bit
FIQ disable
IRQ disable
AT91SAM9G45
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