SAM3S1A Atmel Corporation, SAM3S1A Datasheet - Page 51

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SAM3S1A

Manufacturer Part Number
SAM3S1A
Description
Manufacturer
Atmel Corporation
Datasheets

Specifications of SAM3S1A

Flash (kbytes)
64 Kbytes
Pin Count
48
Max. Operating Frequency
64 MHz
Cpu
Cortex-M3
# Of Touch Channels
17
Hardware Qtouch Acquisition
No
Max I/o Pins
34
Ext Interrupts
34
Usb Transceiver
1
Quadrature Decoder Channels
1
Usb Speed
Full Speed
Usb Interface
Device
Spi
2
Twi (i2c)
2
Uart
3
Ssc
1
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
8
Adc Resolution (bits)
12
Adc Speed (ksps)
1000
Analog Comparators
1
Resistive Touch Screen
No
Temp. Sensor
Yes
Crypto Engine
No
Sram (kbytes)
16
Self Program Memory
YES
Dram Memory
No
Nand Interface
Yes
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
Yes / No
Timers
3
Output Compare Channels
3
Input Capture Channels
3
Pwm Channels
4
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes
10.4.3.15
• 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
6500C–ATARM–8-Feb-11
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
144.
27
19
11
3
“ISB” on page 142
26
18
10
2
Active Stack
Table 10-2 on page 44
Pointer
25
17
9
1
SAM3S
Thread Mode
Privilege
Level
24
16
8
0
for
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