SAM7S256_14 Datasheet, PDF (133/775 Pages) ATMEL Corporation – ARM-based Flash MCU

Lock bits can be read using Get Lock Bit command (GLB). The n^th lock bit is active when the bit n of the bit mask
is set..
Table 20-12. Get Lock Bit Command
Step Handshake Sequence
1
Write handshaking
2
Read handshaking
MODE[3:0]
CMDE
DATA
DATA[15:0] or DATA[7:0]
GLB
Lock Bit Mask Status
0 = Lock bit is cleared
1 = Lock bit is set
20.2.5.5 Flash General-purpose NVM Commands
General-purpose NVM bits (GP NVM bits) can be set using the Set GPNVM command (SGPB). This command
also activates GP NVM bits. A bit mask is provided as argument to the command. When bit 0 of the bit mask is set,
then the first GP NVM bit is activated.
In the same way, the Clear GPNVM command (CGPB) is used to clear general-purpose NVM bits. All the general-
purpose NVM bits are also cleared by the EA command. The general-purpose NVM bit is deactivated when the
corresponding bit in the pattern value is set to 1.
Table 20-13. Set/Clear GP NVM Command
Step Handshake Sequence
MODE[3:0]
DATA[15:0] or DATA[7:0]
1
Write handshaking
CMDE
SGPB or CGPB
2
Write handshaking
DATA
GP NVM bit pattern value
General-purpose NVM bits can be read using the Get GPNVM Bit command (GGPB). The n^th GP NVM bit is active
when bit n of the bit mask is set..
Table 20-14. Get GP NVM Bit Command
Step Handshake Sequence
MODE[3:0]
1
Write handshaking
CMDE
2
Read handshaking
DATA
DATA[15:0] or DATA[7:0]
GGPB
GP NVM Bit Mask Status
0 = GP NVM bit is cleared
1 = GP NVM bit is set
20.2.5.6 Flash Security Bit Command
A security bit can be set using the Set Security Bit command (SSE). Once the security bit is active, the Fast Flash
programming is disabled. No other command can be run. An event on the Erase pin can erase the security bit once
the contents of the Flash have been erased.
The SAM7S512 security bit is controlled by the EFC0. To use the Set Security Bit command, the EFC0 must be
selected using the Select EFC command
Table 20-15. Set Security Bit Command
Step Handshake Sequence
1
Write handshaking
2
Write handshaking
MODE[3:0]
CMDE
DATA
DATA[15:0]
SSE
0
Once the security bit is set, it is not possible to access FFPI. The only way to erase the security bit is to erase the
Flash.
In order to erase the Flash, the user must perform the following:
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
133