Atmel ARM-Based Evaluation Kit for SAM4S16C, 32-Bit ARM® Cortex® Microcontroller ATSAM4S-WPIR-RD ATSAM4S-WPIR-RD Data Sheet

SAM4S Series [DATASHEET]

Atmel-11100G-ATARM-SAM4S-Datasheet_27-May-14

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The NRST pin is bidirectional. It is handled by the on-chip reset controller and can be driven low to provide a reset 

signal to the external components or asserted low externally to reset the microcontroller. It will reset the Core and 

the peripherals except the Backup region (RTC, RTT and Supply Controller). There is no constraint on the length 

of the reset pulse and the reset controller can guarantee a minimum pulse length. The NRST pin integrates a 

permanent pull-up resistor to VDDIO of about 100 kΩ. By default, the NRST pin is configured as an input.

The ERASE pin is used to reinitialize the Flash content (and some of its NVM bits) to an erased state (all bits read 

as logic level 1). It integrates a pull-down resistor of about 100 kΩ to GND, so that it can be left unconnected for 

normal operations.
This pin is debounced by SCLK to improve the glitch tolerance. To avoid unexpected erase at power-up, a 

minimum ERASE pin assertion time is required. This time is defined in 

.

The ERASE pin is a system I/O pin and can be used as a standard I/O. At startup, the ERASE pin is not configured 

as a PIO pin. If the ERASE pin is used as a standard I/O, startup level of this pin must be low to prevent unwanted 

erasing. Refer to 

. Also, if the ERASE pin is 

used as a standard I/O output, asserting the pin to low does not erase the Flash.

WKUP0 and WKUP1 generic wake-up pins can be used as anti-tamper pins. Anti-tamper pins detect intrusion, for 

example, into a housing box. Upon detection through a tamper switch, automatic, asynchronous and immediate 

clear of registers in the backup area will be performed. Anti-tamper pins can be used in all power modes (back-

up/wait/sleep/active). Anti-tampering events can be programmed so that half of the General Purpose Backup 

Registers (GPBR) are erased automatically. See "Supply Controller" section for further description.
RTCOUT0 and RTCOUT1 pins can be used to generate waveforms from the RTC in order to take advantage of 

the RTC inherent prescalers while the RTC is the only powered circuitry (low-power mode, backup mode) or in any 

active mode. Entering backup or low-power modes does not affect the waveform generation outputs. Anti-

tampering pin detection can be synchronized with this signal.