AT91SAM7S128 ATMEL [ATMEL Corporation], AT91SAM7S128 Datasheet - Page 20

• Manufacturer Part Number: AT91SAM7S128
• Manufacturer: ATMEL [ATMEL Corporation]

9.6.4
9.6.5
9.6.6
9.7
20
Fast Flash Programming Interface
AT91SAM7S Series Summary
Security Bit Feature
Non-volatile Brownout Detector Control
Calibration Bits
If a locked-regions erase or program command occurs, the command is aborted and the EFC
trigs an interrupt.
The 16 NVM bits are software programmable through the EFC User Interface. The command
“Set Lock Bit” enables the protection. The command “Clear Lock Bit” unlocks the lock region.
Asserting the ERASE pin clears the lock bits, thus unlocking the entire Flash.
The AT91SAM7S Series features a security bit, based on a specific NVM-Bit. When the security
is enabled, any access to the Flash, either through the ICE interface or through the Fast Flash
Programming Interface, is forbidden. This ensures the confidentiality of the code programmed in
the Flash.
This security bit can only be enabled, through the Command “Set Security Bit” of the EFC User
Interface. 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.
It is important to note that the assertion of the ERASE pin should always be longer than
50 ms.
As the ERASE pin integrates a permanent pull-down, it can be left unconnected during normal
operation. However, it is safer to connect it directly to GND for the final application.
Two general purpose NVM (GPNVM) bits are used for controlling the brownout detector (BOD),
so that even after a power loss, the brownout detector operations remain in their state.
These two GPNVM bits can be cleared or set respectively through the commands “Clear Gen-
eral-purpose NVM Bit” and “Set General-purpose NVM Bit” of the EFC User Interface.
Eight NVM bits are used to calibrate the brownout detector and the voltage regulator. These bits
are factory configured and cannot be changed by the user. The ERASE pin has no effect on the
calibration bits.
The Fast Flash Programming Interface allows programming the device through either a serial
JTAG interface or through a multiplexed fully-handshaked parallel port. It allows gang-program-
ming with market-standard industrial programmers.
The FFPI supports read, page program, page erase, full erase, lock, unlock and protect
commands.
The Fast Flash Programming Interface is enabled and the Fast Programming Mode is entered
when the TST pin and the PA0 and PA1 pins are all tied high and PA2 is tied low.
• GPNVM Bit 0 is used as a brownout detector enable bit. Setting the GPNVM Bit 0 enables
• The GPNVM Bit 1 is used as a brownout reset enable signal for the reset controller. Setting
the BOD, clearing it disables the BOD. Asserting ERASE clears the GPNVM Bit 0 and thus
disables the brownout detector by default.
the GPNVM Bit 1 enables the brownout reset when a brownout is detected, Clearing the
GPNVM Bit 1 disables the brownout reset. Asserting ERASE disables the brownout reset by
default.
6175BS–ATARM–04-Nov-05