Datasheet

35
SAM3S [SUMMARY]
6500ES–ATARM–11-Feb-13
10.1 System Controller and Peripheral Mapping
Please refer to Section 8-1 “SAM3S Product Mapping” on page 30.
All the peripherals are in the bit band region and are mapped in the bit band alias region.
10.2 Power-on-Reset, Brownout and Supply Monitor
The SAM3S embeds three features to monitor, warn and/or reset the chip:
• Power-on-Reset on VDDIO
• Brownout Detector on VDDCORE
• Supply Monitor on VDDIO
10.2.1 Power-on-Reset
The Power-on-Reset monitors VDDIO. It is always activated and monitors voltage at start up but also during power down.
If VDDIO goes below the threshold voltage, the entire chip is reset. For more information, refer to the Electrical
Characteristics section of the datasheet.
10.2.2 Brownout Detector on VDDCORE
The Brownout Detector monitors VDDCORE. It is active by default. It can be deactivated by software through the Supply
Controller (SUPC_MR). It is especially recommended to disable it during low-power modes such as wait or sleep modes.
If VDDCORE goes below the threshold voltage, the reset of the core is asserted. For more information, refer to the
Supply Controller (SUPC) and Electrical Characteristics sections of the datasheet.
10.2.3 Supply Monitor on VDDIO
The Supply Monitor monitors VDDIO. It is not active by default. It can be activated by software and is fully programmable
with 16 steps for the threshold (between 1.9V to 3.4V). It is controlled by the Supply Controller (SUPC). A sample mode
is possible. It allows to divide the supply monitor power consumption by a factor of up to 2048. For more information,
refer to the SUPC and Electrical Characteristics sections of the datasheet.
10.3 Reset Controller
The Reset Controller is based on a Power-on-Reset cell, and a Supply Monitor on VDDCORE.
The Reset Controller is capable to return to the software the source of the last reset, either a general reset, a wake-up
reset, a software reset, a user reset or a watchdog reset.
The Reset Controller controls the internal resets of the system and the NRST pin input/output. It is capable to shape a
reset signal for the external devices, simplifying to a minimum connection of a push-button on the NRST pin to implement
a manual reset.
The configuration of the Reset Controller is saved as supplied on VDDIO.
10.4 Supply Controller (SUPC)
The Supply Controller controls the power supplies of each section of the processor and the peripherals (via Voltage
regulator control)
The Supply Controller has its own reset circuitry and is clocked by the 32 kHz Slow clock generator.
The reset circuitry is based on a zero-power power-on reset cell and a brownout detector cell. The zero-power power-on
reset allows the Supply Controller to start properly, while the software-programmable brownout detector allows detection
of either a battery discharge or main voltage loss.
The Slow Clock generator is based on a 32 kHz crystal oscillator and an embedded 32 kHz RC oscillator. The Slow Clock
defaults to the RC oscillator, but the software can enable the crystal oscillator and select it as the Slow Clock source.