Datasheet

355
SAM4S Series [DATASHEET]
11100F–ATARM–29-Jan-14
The RC calibration for the 4 MHz is set to ‘1000000’.
20.4.3.7 Security Bit Protection
When the security is enabled, access to the Flash, either through the JTAG/SWD interface or through the Fast Flash
Programming interface, is forbidden. This ensures the confidentiality of the code programmed in the Flash.
The security bit is GPNVM0.
Disabling the security bit can only be achieved by asserting the ERASE pin at 1, and after a full Flash erase is performed.
When the security bit is deactivated, all accesses to the Flash are permitted.
20.4.3.8 Unique Identifier
Each part is programmed with a 128 bits unique identifier. It can be used to generate keys for example. To read the
unique identifier, the sequence is:
 Send the Start read unique identifier command (STUI) by writing EEFC_FCR with the STUI command.
 When the unique identifier is ready to be read, the FRDY bit in EEFC_FSR falls.
 The unique identifier is located in the first 128 bits of the Flash memory mapping, thus, at the address
0x00400000-0x004003FF.
 To stop the unique identifier mode, the user needs to send the Stop read unique identifier command (SPUI) by
writing EEFC_FCR with the SPUI command.
 When the SPUI command has been performed, the FRDY bit in EEFC_FSR rises. If an interrupt was enabled by
setting the FRDY bit in EEFC_FMR, the interrupt line of the interrupt controller is activated.
Note that during the sequence, the software cannot run out of Flash.
20.4.3.9 User Signature
Each part contains a user signature of 512 bytes. It can be used for storage. Read, write and erase of this area is
allowed.
To read the user signature, the sequence is as follows:
 Send the Start read user signature command (STUS) by writing EEFC_FCR with the STUS command.
 When the user signature is ready to be read, the FRDY bit in EEFC_FSR falls.
 The user signature is located in the first 512 bytes of the Flash memory mapping, thus, at the address
0x00400000-0x004001FF.
 To stop the user signature mode, the user needs to send the Stop read user signature command (SPUS) by
writing EEFC_FCR with the SPUS command.
 When the SPUI command has been performed, the FRDY bit in EEFC_FSR rises. If an interrupt was enabled by
setting the FRDY bit in EEFC_FMR, the interrupt line of the interrupt controller is activated.
Note that during the sequence, the software cannot run out of Flash or the second plane in case of dual plane.
One error can be detected in EEFC_FSR after this sequence:
 Command Error: a bad keyword has been written in EEFC_FCR.
To write the user signature, the sequence is:
 Write the full page, at any page address, within the internal memory area address space.
 Send the Write user signature command (WUS) by writing EEFC_FCR with the WUS command.
 When programming is completed, the FRDY bit in EEFC_FSR rises. If an interrupt has been enabled by setting
the FRDY bit in EEFC_FMR, the corresponding interrupt line of the interrupt controller is activated.
Two errors can be detected in EEFC_FSR after this sequence:
 Command Error: a bad keyword has been written in EEFC_FCR.
 Flash Error: at the end of the programming, the WriteVerify test of the Flash memory has failed.
To erase the user signature, the sequence is:
 Send the Erase user signature command (EUS) by writing EEFC_FCR with the EUS command.