AT90S4414/8515
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Memory Programming
Program and Data Memory Lock Bits
The AT90S4414/8515 MCU provides two Lock bits which can be left unprogrammed (‘1’) or can be programmed (‘0’) to
obtain the additional features listed in Table 26. The Lock Bits can only be erased with the Chip Erase command.
Note:
1. In Parallel mode, further programming of the Fuse bits are also disabled. Program the Fuse bits before programming the
Lock bits.
Fuse Bits
The AT90S4414/8515 has two Fuse bits, SPIEN and FSTRT.
• When the SPIEN Fuse is programmed (‘0’), Serial Program and Data Downloading is enabled. Default value is
programmed (“0”).
• When the FSTRT Fuse is programmed (‘0’), the short start-up time is selected. Default value is unprogrammed (“1”).
Parts with this bit pre-programmed (‘0’) can be delivered on demand.
The Fuse bits are not accessible in Serial Programming Mode. The status of the Fuse bits is not affected by Chip Erase.
Signature Bytes
All Atmel microcontrollers have a three-byte signature code which identifies the device. This code can be read in both serial
and parallel mode. The three bytes reside in a separate address space.
For the AT90S8515
they are:
1.
$000: $1E (indicates manufactured by Atmel)
2.
$001: $93 (indicates 8KB Flash memory)
3.
$002: $01 (indicates AT90S8515 device when signature byte $001 is $93)
For the AT90S4414
they are:
1.
$000: $1E (indicates manufactured by Atmel)
2.
$001: $92 (indicates 4KB Flash memory)
3.
$002: $01 (indicates AT90S4414 device when signature byte $001 is $92)
Note:
1. When both Lock bits are programmed (Lock mode 3), the signature bytes can not be read in serial mode. Reading the signa-
ture bytes will return: $00, $01 and $02.
Programming the Flash and EEPROM
Atmel’s AT90S4414/8515 offers 4K/8K bytes of In-System Reprogrammable Flash Program memory and 256/512 bytes of
EEPROM Data memory.
The AT90S4414/8515 is shipped with the on-chip Flash Program and EEPROM Data memory arrays in the erased state
(i.e. contents = $FF) and ready to be programmed. This device supports a High-voltage (12V) Parallel programming mode
and a Low-voltage Serial programming mode. The +12V is used for programming enable only, and no current of signifi-
cance is drawn by this pin. The serial programming mode provides a convenient way to download program and data into
the AT90S4414/8515 inside the user’s system.
Table 26. Lock Bit Protection Modes
Memory Lock Bits
Protection Type
Mode
LB1
LB2
1
1
1
No memory lock features enabled.
2
0
1
Further programming of the Flash and EEPROM is disabled.
3
0
0
Same as mode 2, and verify is also disabled.