Atmel SAM9X25, Manual

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14.3 Block Diagram
Figure 14-1. Reset Controller Block Diagram
14.4 Functional Description
14.4.1 Reset Controller Overview
The Reset Controller is made up of an NRST Manager, a Startup Counter and a Reset State
Manager. It runs at Slow Clock and generates the following reset signals:
• proc_nreset: Processor reset line. It also resets the Watchdog Timer.
• backup_nreset: Affects all the peripherals powered by VDDBU.
• periph_nreset: Affects the whole set of embedded peripherals.
• nrst_out: Drives the NRST pin.
These reset signals are asserted by the Reset Controller, either on external events or on soft-
ware action. The Reset State Manager controls the generation of reset signals and provides a
signal to the NRST Manager when an assertion of the NRST pin is required.
The NRST Manager shapes the NRST assertion during a programmable time, thus controlling
external device resets.
The startup counter waits for the complete crystal oscillator startup. The wait delay is given by
the crystal oscillator startup time maximum value that can be found in the section Crystal Oscil-
lator Characteristics in the Electrical Characteristics section of the product documentation.
The Reset Controller Mode Register (RSTC_MR), allowing the configuration of the Reset Con-
troller, is powered with VDDBU, so that its configuration is saved as long as VDDBU is on.
NRST
Startup
Counter
proc_nreset
wd_fault
periph_nreset
backup_neset
SLCK
Reset
State
Manager
Reset Controller
rstc_irq
NRST
Manager
exter_nreset
nrst_out
Main Supply
POR
WDRPROC
user_reset
Backup Supply
POR