SAM3N4A Atmel Corporation, SAM3N4A Datasheet - Page 61

• Manufacturer Part Number: SAM3N4A
• Manufacturer: Atmel Corporation

Specifications of SAM3N4A

• Flash (kbytes): 256 Kbytes
• Pin Count: 48
• Max. Operating Frequency: 48 MHz
• Cpu: Cortex-M3
• # Of Touch Channels: 32
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 79
• Ext Interrupts: 79
• Quadrature Decoder Channels: 2
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 2
• 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): 24
• Self Program Memory: YES
• 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): 1.62 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 6
• Output Compare Channels: 6
• Input Capture Channels: 3
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

10.5.5.2
10.5.6
10.5.6.1
10.5.7
10.5.7.1
10.5.7.2
11011A–ATARM–04-Oct-10
Memory endianness
Synchronization primitives
Directly accessing a bit-band region
Little-endian format
A Load-Exclusive instruction
A Store-Exclusive instruction
Reading a word in the alias region:
“Behavior of memory accesses” on page 57
word accesses to the bit-band regions.
The processor views memory as a linear collection of bytes numbered in ascending order from
zero. For example, bytes 0-3 hold the first stored word, and bytes 4-7 hold the second stored
word. or
In little-endian format, the processor stores the least significant byte of a word at the lowest-
numbered byte, and the most significant byte at the highest-numbered byte. For example:
The Cortex-M3 instruction set includes pairs of synchronization primitives. These provide a non-
blocking mechanism that a thread or process can use to obtain exclusive access to a memory
location. Software can use them to perform a guaranteed read-modify-write memory update
sequence, or for a semaphore mechanism.
A pair of synchronization primitives comprises:
Used to read the value of a memory location, requesting exclusive access to that location.
Used to attempt to write to the same memory location, returning a status bit to a register. If this
bit is:
0: it indicates that the thread or process gained exclusive access to the memory, and the write
succeeds,
1: it indicates that the thread or process did not gain exclusive access to the memory, and no
write is performed,
The pairs of Load-Exclusive and Store-Exclusive instructions are:
Address A
• 0x00000000 indicates that the targeted bit in the bit-band region is set to zero
• 0x00000001 indicates that the targeted bit in the bit-band region is set to 1
• the word instructions LDREX and STREX
A+1
A+2
A+3
“Little-endian format”
7
Memory
B0
B1
B2
B3
0
lsbyte
msbyte
31
B3
describes how words of data are stored in memory.
24 23
B2
Register
16 15
B1
describes the behavior of direct byte, halfword, or
8 7
B0
0
SAM3N
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