SAM7XC256 Atmel Corporation, SAM7XC256 Datasheet - Page 78

• Manufacturer Part Number: SAM7XC256
• Manufacturer: Atmel Corporation

Specifications of SAM7XC256

• 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
• Dac Resolution (bits): No
• Temp. Sensor: No
• Crypto Engine: AES/DES
• 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

Memory Interface
3.3.4
3-8
Merged IS cycles
Where possible the ARM7TDMI processor broadcasts the address for the next access,
so that decode can start, but the memory controller must not commit to a memory
access. This is shown in Figure 3-4 and, is further described in Nonsequential memory
cycle on page 3-6.
Where possible, the ARM7TDMI processor performs an optimization on the bus to
allow extra time for memory decode. When this happens, the address of the next
memory cycle is broadcast on this bus during an internal cycle. This enables the
memory controller to decode the address, but it must not initiate a memory access
during this cycle. In a merged IS cycle, the next cycle is a sequential cycle to the same
memory location. This commits to the access, and the memory controller must initiate
the memory access. This is shown in Figure 3-5 on page 3-9.
Copyright © 1994-2001. All rights reserved.
nMREQ
D[31:0]
A[31:0]
MCLK
nRAS
nCAS
SEQ
N-cycle
a
a+4
S-cycle
Figure 3-4 Internal cycles
a+8
I-cycle
ARM DDI 0029G
a+12
C-cycle