SAM7S321 Atmel Corporation, SAM7S321 Datasheet - Page 25

• Manufacturer Part Number: SAM7S321
• Manufacturer: Atmel Corporation

Specifications of SAM7S321

• Flash (kbytes): 32 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 55 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 32
• Ext Interrupts: 32
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 1
• Twi (i2c): 1
• Uart: 3
• Ssc: 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): 8
• Self Program Memory: NO
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8/3.3
• 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

1.1.2
ARM DDI 0029G
Memory access
During normal operation, while one instruction is being executed, its successor is being
decoded, and a third instruction is being fetched from memory.
The program counter points to the instruction being fetched rather than to the instruction
being executed. This is important because it means that the Program Counter (PC)
value used in an executing instruction is always two instructions ahead of the address.
The ARM7TDMI core has a Von Neumann architecture, with a single 32-bit data bus
carrying both instructions and data. Only load, store, and swap instructions can access
data from memory.
Data can be:
•
•
•
Words must be aligned to 4-byte boundaries. Halfwords must be aligned to 2-byte
boundaries.
8-bit (bytes)
16-bit (halfwords)
32-bit (words).
Copyright © 1994-2001. All rights reserved.
Execute
Decode
Fetch
Instruction fetched from memory
Decoding of registers used in
instruction
Register(s) read from register bank
Perform shift and ALU operations
Write register(s) back to register bank
Figure 1-1 Instruction pipeline
Introduction
1-3