AT90S/LS2333 and AT90S/LS4433
71
Memory Programming
Program and Data Memory Lock Bits
The AT90S2333/4433 MCU provides two Lock bits which can be left unprogrammed (‘1’) or can be programmed (‘0’) to
obtain the additional features listed in Table 28. The Lock bits can only be erased with the Chip Erase command.
Note:
1. In Parallel mode, programming of the Fuse bits are also disabled. Program the Fuse bits before programming the Lock bits.
Fuse Bits
The AT90S2333/4433 has six Fuse bits, SPIEN, BODLEVEL, BODEN and CKSEL2..0.
• When the SPIEN Fuse is programmed (‘0’), Serial Program and Data Downloading is enabled. Default value is
programmed (‘0’). This bit is not accessible in serial programming mode.
• The BODLEVEL Fuse selects the Brown-Out Detection Level and changes the Start-up times. See “Brown-Out
Detection” on page 21. Default value is unprogrammed (‘1’).
• When the BODEN Fuse is programmed (‘0’), the Brown- Out Detector is enabled. See “Brown-Out Detection” on
page 21. Default value is unprogrammed (‘1’).
• CKSEL2..0: See Table 5, “Reset Delay Selections”, for which combination of CKSEL2..0 to use. Default value is ‘010’.
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 AT90S4433
they are:
1.
$000: $1E (indicates manufactured by Atmel)
2.
$001: $92 (indicates 4KB Flash memory)
3.
$002: $03 (indicates AT90S4433 device when signature byte $001 is $92)
For AT90S2333
they are:
1.
$000: $1E (indicates manufactured by Atmel)
2.
$001: $91 (indicates 2KB Flash memory)
3.
$002: $05 (indicates AT90S2333 device when signature byte $001 is $91)
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 AT90S2333/4433 offers 2K/4K bytes of in-system reprogrammable Flash Program memory and 128/256 bytes of
EEPROM Data memory.
The AT90S2333/4433 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 AT90S2333/4433 inside the user’s system.
Table 28. 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.