SAM3S1A Atmel Corporation, SAM3S1A Datasheet - Page 224

• Manufacturer Part Number: SAM3S1A
• Manufacturer: Atmel Corporation

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

12.3.2
12.3.2.1
12.3.2.2
224
SAM3S
NRST Manager
NRST Signal or Interrupt
NRST External Reset Control
The Reset Controller Mode Register (RSTC_MR), allowing the configuration of the Reset Con-
troller, is powered with VDDIO, so that its configuration is saved as long as VDDIO is on.
After power-up, NRST is an output during the ERSTL time period defined in the RSTC_MR.
When ERSTL has elapsed, the pin behaves as an input and all the system is held in reset if
NRST is tied to GND by an external signal.
The NRST Manager samples the NRST input pin and drives this pin low when required by the
Reset State Manager.
Figure 12-2. NRST Manager
The NRST Manager samples the NRST pin at Slow Clock speed. When the line is detected low,
a User Reset is reported to the Reset State Manager.
However, the NRST Manager can be programmed to not trigger a reset when an assertion of
NRST occurs. Writing the bit URSTEN at 0 in RSTC_MR disables the User Reset trigger.
The level of the pin NRST can be read at any time in the bit NRSTL (NRST level) in RSTC_SR.
As soon as the pin NRST is asserted, the bit URSTS in RSTC_SR is set. This bit clears only
when RSTC_SR is read.
The Reset Controller can also be programmed to generate an interrupt instead of generating a
reset. To do so, the bit URSTIEN in RSTC_MR must be written at 1.
The Reset State Manager asserts the signal ext_nreset to assert the NRST pin. When this
occurs, the “nrst_out” signal is driven low by the NRST Manager for a time programmed by the
field ERSTL in RSTC_MR. This assertion duration, named EXTERNAL_RESET_LENGTH, lasts
2
and 2 seconds. Note that ERSTL at 0 defines a two-cycle duration for the NRST pulse.
This feature allows the Reset Controller to shape the NRST pin level, and thus to guarantee that
the NRST line is driven low for a time compliant with potential external devices connected on the
system reset.
(ERSTL+1)
Slow Clock cycles. This gives the approximate duration of an assertion between 60 µs
NRST
Figure 12-2
RSTC_SR
nrst_out
URSTS
NRSTL
shows the block diagram of the NRST Manager.
External Reset Timer
RSTC_MR
RSTC_MR
ERSTL
URSTEN
RSTC_MR
URSTIEN
interrupt
sources
Other
user_reset
exter_nreset
6500C–ATARM–8-Feb-11
rstc_irq