SAM7S256 Atmel Corporation, SAM7S256 Datasheet - Page 157

• Manufacturer Part Number: SAM7S256
• Manufacturer: Atmel Corporation

Specifications of SAM7S256

• Flash (kbytes): 256 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): 64
• 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

6.9
ARM DDI 0029G
Destination registers
Single register
Load multiple registers
The first cycle of the LDM instruction is used to calculate the address of the first word
to be transferred, while performing a prefetch from memory. The second cycle fetches
the first word, and performs the base modification. During the third cycle, the first word
is moved to the appropriate destination register while the second word is fetched from
memory, and the modified base is latched internally in case it is needed to restore
processor state after an abort. The third cycle is repeated for subsequent fetches until the
last data word has been accessed, then the final (internal) cycle moves the last word to
its destination register. The cycle timings are listed in Table 6-12.
The last cycle can be merged with the next instruction prefetch to form a single memory
N-cycle. If an abort occurs, the instruction continues to completion, but all register
modification after the abort is prevented. The final cycle is altered to restore the
modified base register (that could have been overwritten by the load activity before the
abort occurred).
When the PC is in the list of registers to be loaded the current instruction pipeline must
be invalidated.
The PC is always the last register to be loaded, so an abort at any point prevents the PC
from being overwritten.
LDM with PC as a destination register is not available in Thumb state. Use
Cycle
1
2
3
Note
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to perform the same function.
Address
pc+2L
alu
pc+3L
pc+3L
Table 6-12 Load multiple registers instruction cycle operations
MAS[1:0]
i
2
i
nRW
0
0
0
Data
(pc+2L)
(alu)
-
nMREQ
0
1
0
Instruction Cycle Timings
SEQ
0
0
1
nOPC
0
1
1
6-15