ATSAM3S4CA-CU Atmel, ATSAM3S4CA-CU Datasheet - Page 61

• Manufacturer Part Number: ATSAM3S4CA-CU
• Description: IC MCU 32BIT 256KB FLASH 100BGA
• Manufacturer: Atmel
• Series: SAM3Sr

Specifications of ATSAM3S4CA-CU

• Core Processor: ARM® Cortex-M3™
• Core Size: 32-Bit
• Speed: 64MHz
• Connectivity: EBI/EMI, I²C, MMC, SPI, SSC, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, DMA, I²S, POR, PWM, WDT
• Number Of I /o: 79
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 48K x 8
• Voltage - Supply (vcc/vdd): 1.62 V ~ 1.95 V
• Data Converters: A/D 16x10/12b, D/A 2x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-LFBGA
• Processor Series: ATSAM3x
• Core: ARM Cortex M3
• 3rd Party Development Tools: JTRACE-CM3, MDK-ARM, RL-ARM, ULINK2
• Development Tools By Supplier: ATSAM3S-EK
• Package: 100LFBGA
• Device Core: ARM Cortex M3
• Family Name: AT91
• Maximum Speed: 64 MHz
• Operating Supply Voltage: 1.8|3.3 V
• Data Bus Width: 32 Bit
• Number Of Programmable I/os: 79
• Interface Type: I2C/I2S/SPI/UART/USART/USB
• On-chip Adc: 16-chx12-bit
• On-chip Dac: 2-chx12-bit
• Number Of Timers: 6
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

10.5.6.1
10.5.7
10.5.7.1
10.5.7.2
6500C–ATARM–8-Feb-11
Synchronization primitives
Little-endian format
A Load-Exclusive instruction
A Store-Exclusive instruction
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:
Software must use a Load-Exclusive instruction with the corresponding Store-Exclusive
instruction.
To perform a guaranteed read-modify-write of a memory location, software must:
Address A
• the word instructions LDREX and STREX
• the halfword instructions LDREXH and STREXH
• the byte instructions LDREXB and STREXB.
• Use a Load-Exclusive instruction to read the value of the location.
• Update the value, as required.
• Use a Store-Exclusive instruction to attempt to write the new value back to the memory
location, and tests the returned status bit. If this bit is:
0: The read-modify-write completed successfully,
A+1
A+2
A+3
7
Memory
B0
B1
B2
B3
0
lsbyte
msbyte
31
B3
24 23
B2
Register
16 15
B1
8 7
B0
0
SAM3S Preliminary
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