SAM7SE256 Atmel Corporation, SAM7SE256 Datasheet - Page 148

• Manufacturer Part Number: SAM7SE256
• Manufacturer: Atmel Corporation

Specifications of SAM7SE256

• Flash (kbytes): 256 Kbytes
• Pin Count: 144
• Max. Operating Frequency: 48 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 88
• Ext Interrupts: 88
• 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): 32
• Self Program Memory: NO
• External Bus Interface: 1
• Dram Memory: sdram
• Nand Interface: Yes
• 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: Yes / No
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 3
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: No

Instruction Cycle Timings
6.4
6-6
Branch and Exchange
Cycle
1
2
3
A Branch and Exchange (BX) operation takes three cycles and is similar to a branch. In
the first cycle, the branch destination and the new core state are extracted from the
register source, whilst performing a prefetch from the current PC. This prefetch is
performed in all cases, since by the time the decision to take the branch has been
reached, it is already too late to prevent the prefetch.
During the second cycle, a fetch is performed from the branch destination address using
the new instruction width, dependent on the state that has been selected.
The third cycle performs a fetch from the destination address +2 or +4 (dependent on
the new specified state), refilling the instruction pipeline.
The cycle timings are listed in Table 6-3 where:
•
•
•
W and w represent the instruction width before and after the BX respectively. The
width equals four bytes in ARM state and two bytes in Thumb state. For example,
when changing from ARM to Thumb state, W equals four and w equals two
I and i represent the memory access size before and after the BX respectively.
MAS[1:0] equals two in ARM state and one in Thumb state. When changing
from Thumb to ARM state, I equals one and i equals two.
T and t represent the state of the TBIT before and after the BX respectively. TBIT
equals 0 in ARM state and 1 in Thumb state. When changing from ARM to
Thumb state, T equals 0 and t equals 1.
pc + 2W
alu
alu+w
alu + 2w
Address
Copyright © 1994-2001. All rights reserved.
MAS[1:0]
I
i
i
Table 6-3 Branch and exchange instruction cycle operations
nRW
0
0
0
Data
(pc+2W)
(alu)
(alu+w)
nMREQ
0
0
0
SEQ
0
1
1
nOPC
0
0
0
ARM DDI 0029G
T
t
t
TBIT