SAM7X128 Atmel Corporation, SAM7X128 Datasheet - Page 250

• Manufacturer Part Number: SAM7X128
• Manufacturer: Atmel Corporation

Specifications of SAM7X128

• Flash (kbytes): 128 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 55 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 62
• Ext Interrupts: 62
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 2
• Twi (i2c): 1
• Uart: 3
• Can: 1
• Ssc: 1
• Ethernet: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 384
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 32
• Self Program Memory: NO
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 3.3
• Operating Voltage (vcc): 3.0 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 3
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: No

Debug in Depth
B.10
B.10.1 Breakpoint with Prefetch Abort
B.10.2 Interrupts
B.10.3 Data Aborts
B-32
Priorities and exceptions
When a breakpoint, or a debug request occurs, the normal flow of the program is
interrupted. Debug can be treated as another type of exception. The interaction of the
debugger with other exceptions is described in Behavior of the program counter during
debug on page B-29. This section covers the following priorities:
•
•
•
When a breakpointed instruction fetch causes a Prefetch Abort, the abort is taken and
the breakpoint is disregarded. Usually, Prefetch Aborts occur when, for example, an
access is made to a virtual address that does not physically exist and the returned data
is therefore invalid. In such a case, the normal action of the operating system is to swap
in the page of memory and to return to the previously-invalid address. This time, when
the instruction is fetched and providing the breakpoint is activated, it can be
data-dependent, the ARM7TDMI core enters debug state.
The Prefetch Abort, therefore, takes higher priority than the breakpoint.
When the ARM7TDMI core enters debug state, interrupts are automatically disabled.
If an interrupt is pending during the instruction prior to entering debug state, the
ARM7TDMI core enters debug state in the mode of the interrupt. On entry to debug
state, the debugger cannot assume that the ARM7TDMI core is in the mode expected
by the user program. The ARM7TDMI core must check the PC, the CPSR, and the
SPSR to accurately determine the reason for the exception.
Debug, therefore, takes higher priority than the interrupt, but the ARM7TDMI core
does remember that an interrupt has occurred.
When a Data Abort occurs on a watchpointed access, the ARM7TDMI core enters
debug state in abort mode. The watchpoint, therefore, has higher priority than the abort,
but the ARM7TDMI core remembers that the abort happened.
Breakpoint with Prefetch Abort on page B-32
Interrupts on page B-32
Data Aborts on page B-32.
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ARM DDI 0029G