SAM7X256 Atmel Corporation, SAM7X256 Datasheet - Page 249

• Manufacturer Part Number: SAM7X256
• Manufacturer: Atmel Corporation

Specifications of SAM7X256

• Flash (kbytes): 256 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): 64
• 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

B.9.5
B.9.6
ARM DDI 0029G
System speed access
Summary of return address calculations
This code restores the PC and restarts the program from the next instruction.
When a system speed access is performed during debug state, the value of the PC
increases by three addresses. System speed instructions access the memory system and
so it is possible for aborts to take place. If an abort occurs during a system speed
memory access, the ARM7TDMI core enters abort mode before returning to debug
state.
This is similar to an aborted watchpoint, but the problem is much harder to fix because
the abort was not caused by an instruction in the main program and so the PC does not
point to the instruction that caused the abort. An abort handler usually looks at the PC
to determine the instruction that caused the abort and also the abort address. In this case,
the value of the PC is invalid, but because the debugger can determine which location
was being accessed, the debugger can be written to help the abort handler fix the
memory system.
The calculation of the branch return address is as follows:
•
•
where N is the number of debug speed instructions executed, including the final branch,
and S is the number of system speed instructions executed.
for normal breakpoint and watchpoint, the branch is:
for entry through debug request, DBGRQ, or watchpoint with exception, the
branch is:
Copyright © 1994-2001. All rights reserved.
Debug in Depth
B-31