ATSAM3U-EK Atmel, ATSAM3U-EK Datasheet - Page 250

• Manufacturer Part Number: ATSAM3U-EK
• Description: KIT EVAL FOR AT91SAM3U CORTEX
• Manufacturer: Atmel
• Type: MCUr

Specifications of ATSAM3U-EK

• Contents: Board
• Processor To Be Evaluated: SAM3U
• Data Bus Width: 32 bit
• Interface Type: RS-232, USB
• Operating Supply Voltage: 3 V
• Silicon Manufacturer: Atmel
• Core Architecture: ARM
• Core Sub-architecture: Cortex - M3
• Silicon Core Number: SAM3U4E
• Silicon Family Name: SAM3U
• Kit Contents: Board CD Docs
• Rohs Compliant: Yes
• For Use With/related Products: AT91SAM3U
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

16.3.4.2
16.3.4.3
Figure 16-4. User Reset State
250
periph_nreset
proc_nreset
(nrst_out)
RSTTYP
SAM3U Series
NRST
SLCK
NRST
MCK
Backup Reset
User Reset
A Backup reset occurs when the chip returns from Backup mode. The vddcore_nreset signal is
asserted by the Supply Controller when a Backup reset occurs.
The field RSTTYP in RSTC_SR is updated to report a Backup Reset.
The User Reset is entered when a low level is detected on the NRST pin and the bit URSTEN in
RSTC_MR is at 1. The NRST input signal is resynchronized with SLCK to insure proper behav-
ior of the system.
The User Reset is entered as soon as a low level is detected on NRST. The Processor Reset
and the Peripheral Reset are asserted.
The User Reset is left when NRST rises, after a two-cycle resynchronization time and a 3-cycle
processor startup. The processor clock is re-enabled as soon as NRST is confirmed high.
When the processor reset signal is released, the RSTTYP field of the Status Register
(RSTC_SR) is loaded with the value 0x4, indicating a User Reset.
T h e
EXTERNAL_RESET_LENGTH Slow Clock cycles, as programmed in the field ERSTL. How-
ever, if NRST does not rise after EXTERNAL_RESET_LENGTH because it is driven low
externally, the internal reset lines remain asserted until NRST actually rises.
Resynch.
2 cycles
Any
Freq.
Any
N R S T
>= EXTERNAL RESET LENGTH
M a n a g e r
g u a r a n t e e s
Resynch.
2 cycles
XXX
t h a t
Processor Startup
t h e
= 2 cycles
N R S T
l i n e
0x4 = User Reset
i s
6430D–ATARM–25-Mar-11
a s s e r t e d
f o r