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Memory Programming
Program and Data
Memory Lock Bits
Fuse Bits in
AT90S/LS2323
Fuse Bits in
AT90S/LS2343
Signature Bytes
1004D–09/01
The AT90S2323/2343 MCU provides two Lock bits that can be left unprogrammed ("1")
or can be programmed ("0") to obtain the additional features listed in Table 14. The Lock
bits can only be erased with the Chip Erase operation.
Table 14. Lock Bit Protection Modes
Memory Lock Bits
Mode
LB1
LB2
1
1
1
2
0
1
3
0
0
Note:
1. In the high-voltage Serial Programming mode, further programming of the Fuse bits
are also disabled. Program the Fuse bits before programming the Lock bits.
The AT90S/LS2323 has two Fuse bits, SPIEN and FSTRT.
•
When the SPIEN Fuse is programmed ("0"), Serial Program and Data Downloading
are enabled. Default value is programmed ("0"). This bit is not accessible in the low-
voltage Serial Programming mode.
•
When the FSTRT Fuse is programmed ("0"), the shortest start-up time is selected
as indicated in Table 6 on page 21. Default value is programmed ("0"). Changing the
FSTRT Fuse does not take effect until the next Power-on Reset. In AT90S/LS2343
the start-up time is fixed.
The status of the Fuse bits is not affected by Chip Erase.
The AT90S/LS2343 has two Fuse bits, SPIEN and RCEN.
•
When the SPIEN Fuse is programmed ("0"), Serial Program and Data Downloading
are enabled. Default value is programmed ("0"). This bit is not accessible in the low-
voltage Serial Programming mode.
•
When the RCEN Fuse is programmed ("0"), the internal RC oscillator is selected as
the MCU clock source. Default value is programmed ("0") in AT90LS2343-1. Default
value is un-programmed ("1") in AT90LS2343-4 and AT90S2343-10. Changing the
RCEN Fuse does not take effect until the next Power-on Reset. AT90S/LS2323
cannot select the internal RC oscillator as the MCU source.
The status of the Fuse bits is not affected by Chip Erase.
All Atmel microcontrollers have a three-byte signature code that identifies the device.
The three bytes reside in a separate address space.
(Note:)
For the AT90S/LS2323
1. $000: $1E (indicates manufactured by Atmel)
2. $001: $91 (indicates 2K bytes Flash memory)
3. $002: $02 (indicates AT90S/LS2323 when signature byte $001 is $91)
(Note:)
For AT90S/LS2343
1. $000: $1E (indicates manufactured by Atmel)
2. $001: $91 (indicates 2K bytes Flash memory)
Protection Type
No memory lock features enabled.
Further programming of the Flash and EEPROM is disabled.
Same as mode 2, and verify is also disabled.
, they are:
, they are:
AT90S/LS2323/2343
(1)
37
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