Datasheet

124
6120F–ATARM–03-Oct-06
AT91SAM7X512/256/128 Preliminary
In the same way, the Clear Fuse command (CFB) 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.
General-purpose NVM bits can be read using the Get Fuse Bit command (GFB). The n
th
GP
NVM bit is active when bit n of the bit mask 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 AT91SAM7X512 security bit is controlled by the EFC0. To use the Set Security Bit com-
mand, the EFC0 must be selected using the Select EFC command.
20.2.5.7 AT91SAM7X512 Select EFC Command
The commands WPx, EA, xLB, xFB are executed using the current EFC controller. The default
EFC controller is EFC0. The Select EFC command (SEFC) allows selection of the current
EFC controller.
20.2.5.8 Memory Write Command
This command is used to perform a write access to any memory location.
Table 20-11. Set/Clear GP NVM Command
Step Handshake Sequence MODE[3:0] DATA[15:0]
1 Write handshaking CMDE SFB or CFB
2 Write handshaking DATA GP NVM bit pattern value
Table 20-12. Get GP NVM Bit Command
Step Handshake Sequence MODE[3:0] DATA[15:0]
1 Write handshaking CMDE GFB
2 Read handshaking DATA
GP NVM Bit Mask Status
0 = GP NVM bit is cleared
1 = GP NVM bit is set
Table 20-13. Set Security Bit Command
Step Handshake Sequence MODE[3:0] DATA[15:0]
1 Write handshaking CMDE SSE
2 Write handshaking DATA 0
Table 20-14. Select EFC Command
Step Handshake Sequence MODE[3:0] DATA[15:0]
1 Write handshaking CMDE SEFC
2 Write handshaking DATA
0 = Select EFC0
1 = Select EFC1