ATSAM3X4EA-AU Atmel, ATSAM3X4EA-AU Datasheet - Page 69

• Manufacturer Part Number: ATSAM3X4EA-AU
• Description: ARM Microcontrollers - MCU QFP144,GREEN, IND TEMP, MRL A
• Manufacturer: Atmel

Specifications of ATSAM3X4EA-AU

• Rohs: yes
• Core: ARM Cortex M3
• Processor Series: SAM3X
• Data Bus Width: 32 bit
• Maximum Clock Frequency: 84 MHz
• Program Memory Size: 256 KB
• Data Ram Size: 64 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 2.4 V to 3.6 V
• Operating Temperature Range: - 40 C to +85 C
• Package / Case: LQFP-144
• Mounting Style: SMD/SMT
• Factory Pack Quantity: 60

12.4.3.15
• Active stack pointer
Defines the current stack:
0: MSP is the current stack pointer
1: PSP is the current stack pointer.
In Handler mode this bit reads as zero and ignores writes.
• Thread mode privilege level
Defines the Thread mode privilege level:
0: privileged
1: unprivileged.
Handler mode always uses the MSP, so the processor ignores explicit writes to the active stack pointer bit of the CON-
TROL register when in Handler mode. The exception entry and return mechanisms update the CONTROL register.
In an OS environment, ARM recommends that threads running in Thread mode use the process stack and the kernel and
exception handlers use the main stack.
By default, Thread mode uses the MSP. To switch the stack pointer used in Thread mode to the PSP, use the MSR instruc-
tion to set the Active stack pointer bit to 1, see
When changing the stack pointer, software must use an ISB instruction immediately after the MSR instruction. This
ensures that instructions after the ISB execute using the new stack pointer. See
11057B–ATARM–28-May-12
11057B–ATARM–28-May-12
31
23
15
7
CONTROL register
30
22
14
6
The CONTROL register controls the stack used and the privilege level for software execution
when the processor is in Thread mode. See the register summary in
its attributes. The bit assignments are:
29
21
13
5
Reserved
“MSR” on page
28
20
12
4
Reserved
Reserved
Reserved
152.
27
19
11
3
“ISB” on page 150
26
18
10
2
Active Stack
Table 12-2 on page 62
Pointer
25
17
9
1
SAM3X/A
SAM3X/A
Thread Mode
Privilege
Level
24
16
8
0
for
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