SAM4CM Series [DATASHEET]
Atmel-11203C-ATARM-SAM4CM32-SAM4CM16-SAM4CM8-Datasheet_06-Oct-14
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Command Error: A bad keyword has been written in EEFC_FCR.
Access to the Flash in read is permitted when a set, clear or Get GPNVM Bit command is performed.
Note:
22.4.3.6Calibration Bit
Calibration bits do not interfere with the embedded Flash memory plane.
The calibration bits cannot be modified.
The status of calibration bits are returned by the EEFC. The sequence is:
1.
Issue the Get CALIB Bit command by writing EEFC_FCR with GCALB (see
Table 22-2
). The FARG field
is meaningless.
2.
Calibration bits can be read by the software application in EEFC_FRR. The first word read corresponds to
the first 32 calibration bits. The following reads provide the next 32 calibration bits as long as it is meaningful.
Extra reads to EEFC_FRR return 0.
The 4/8/12 MHz fast RC oscillator is calibrated in production. This calibration can be read through the Get CALIB
Bit command. The table below shows the bit implementation for each frequency:
The RC calibration for the 4 MHz is set to ‘1000000’.
22.4.3.7Security 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.
22.4.3.8Unique Identifier
Each device is programmed with a 2 × 512-byte unique identifier. It can be used to generate keys for example. For
dual-plane devices, the unique ID is accessible on both memory planes.
To read the unique identifier, the sequence is:
1.
Send the Start Read Unique Identifier (STUI) command by writing EEFC_FCR with the STUI command.
2.
When the unique identifier is ready to be read, the bit EEFC_FSR.FRDY falls.
3.
The unique identifier is located at the address 0x1000000-0x10003FF, in the first 128 bits of the Flash
memory mapping.
4.
To stop the unique identifier mode, the user needs to send the Stop Read Unique Identifier (SPUI) command
by writing EEFC_FCR with the SPUI command.
5.
When the SPUI command has been performed, the bit EEFC_FSR.FRDY rises. If an interrupt was enabled
by setting the bit EEFC_FMR.FRDY, 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.
22.4.3.9User 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:
Table 22-5.
Calibration Bit Indexes
RC Calibration Frequency
EEFC_FRR Bits
8 MHz output
[28–22]
12 MHz output
[38–32]