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Functional Description
216
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
System Control
4.1.6.5
Hibernation Mode
In this mode, the power supplies are turned off to the main part of the microcontroller and only the circuitry
of the Hibernation module is active. An external wake event or RTC event is required to return the
microcontroller to run mode. When exiting hibernation mode, the Cortex-M4F processor and peripherals
other than the Hibernation module see a normal "power on" sequence and the processor starts running
code. If the Hibernation module has been put in hibernation mode and a reset occurs, the reset handler
should read the HIB Raw Interrupt Status (HIBRIS) register in the Hibernation module to determine the
cause of the reset.
4.1.6.6
Hardware System Service Request
The Hardware System Service Request (HSSR) register can issue a request that returns a device to
factory settings. An HSSR consists of writing the appropriate key and data structure address offset to the
HSSR register in the System Control module. Any HSSR initiates a reset event as the first event in the
process. Then the HSSR register is evaluated.
To write to the HSSR register, the KEY field must be 0xCA. The CDOFF field in the HSSR register can
have one of the following values:
•
0x00.0000: No request or the previous request completed successfully
•
0xFF.FFFF: No request and the previous request failed
•
Anything else: The offset into SRAM of a HSSR request structure
During the HSSR routine, if any value other than 0x00.0000 or 0xFF.FFFF is in the CDOFF field, the
offset is examined for validity, and the structure to which it points is examined for validity. If either is
invalid, the request fails, and 0xFF.FFFF is written to the CDOFF field.
The offset is valid if all the following conditions are met:
•
The CDOFF value is word aligned (that is, the two LSBs are both zero).
•
The CDOFF value is at least 0x2000.4000.
•
The CDOFF value is at most 0x2003.FFF0.
After a valid HSSR offset is determined, the following structure is examined in the SRAM that is indicated
by the CDOFF field in the HSSR register. To initiate a return-to-factory settings function, the data structure
must be:
•
Request (32 bits) = 0xFEED.0001
•
Data 1 (32 bits) = 0x0201.0100
•
Data 2 (32 bits) = 0x0D08.0503
•
Data 3 (32 bits) = 0x5937.2215
If the data bytes are correct, the device is returned to factory condition. During the return-to-factory
settings function, the following events occur:
•
The RAM is erased in the Hibernation module.
•
The system SRAM is erased.
•
The FMPPEn registers are set to 0xFFFF.FFFF (to allow a flash erase operation to occur).
•
The EEPROM pages are erased.
•
A mass erase of the flash array occurs.
•
The BOOTCFG register is written with 0xFFFF.FFFE.
When the return-to-factory settings sequence is completed, the CDOFF field of the HSSR register is
written with 0x00.0000, indicating a successful completion and activating a system reset.