Specifications

11
3706C–MICRO–2/11
AT89LP3240/6440
3. Memory Organization
The AT89LP3240/6440 uses a Harvard Architecture with separate address spaces for program
and data memory. The program memory has a regular linear address space with support for 64K
bytes of directly addressable application code. The data memory has 256 bytes of internal RAM
and 128 bytes of Special Function Register I/O
space. The AT89LP3240/6440 supports external
data memory with portions of the external data memory space implemented on chip as Extra
RAM and nonvolatile Flash data memory. External program memory is not supported. The mem-
ory address spaces of the AT89LP3240/6440 are listed in Table 3-1.
3.1 Program Memory
The AT89LP3240/6440 contains 32K/64K bytes of on-chip In-System Programmable Flash
memory for program storage. The Flash memory has an endurance of at least 100,000
write/erase cycles and a minimum data retention time of 10 years. The reset and interrupt vec-
tors are located within the first 83 bytes of program memory (refer to Table 9-1 on page 41).
Constant tables can
be allocated within the entire 32K/64K program memory address space for
access by the MOVC instruction. The AT89LP3240/6440 does not support external program
memory. A map of the AT89LP3240/6440 program memory is shown in Figure 3-1.
3.1.1 SIG
In addition to the 64K code space, the AT89LP3240/6440 also supports a 256-byte User Signa-
ture Arra y and a 128-byte Atmel Signa ture Array tha
t are accessible by the CPU. The Atmel
Signature Array is initialized with the Device ID in the factory. The second page of the User Sig-
nature Array (0180H–01FFH) is initialized with analog configuration data including the Internal
RC Oscillator ca libration byte. The User Signature Array is available for user identification codes
or const
ant pa rameter data. Data stored in the signature array is not secure. S ecurity bits will
disable writes to the array; however, reads by an externa l device programmer are always
allowed.
In order to read from the signature arrays, the SIGEN bit (DPCF.3) must be set (See Table 5-5
on p
age 28). While SIGEN is one, MOVC A,@A+DPTR will access the signature arrays. The
User Signature Array is mapped from addresses 0100h to 01FFh and the Atmel Signature Array
is mapped from addresses 0000h to 007Fh. S IGEN must be cleared before using MOVC to
access the code memory. The User Signature Array may also be modified b
y the In-Application
Programming interface. When IAP = 1 and SIGEN = 1, MOVX @DPTR instructions will access
the array (See Section 3.5 on page 21).
Table 3-1. AT89LP3240/6440 Memory Address Spaces
Name Description Range
DATA Directly addressable internal RAM 00H–7FH
IDATA Indirectly addressable internal RAM and stack space 00H–FFH
SFR Directly addressable I/O register space 80H–FFH
EDATA On-chip Extra RAM and extended stack space 0000H–0FFFH
FDATA On-chip nonvolatile Flash data memory 1000H–2FFFH
XDATA External data memory 3000H–FFFFH
CODE
On-chip nonvolatile Flash program memory (AT89LP3240) 0000H–7FFFH
On-chip nonvolatile Flash program memory (AT89LP6440) 0000H–FFFFH
SIG On-chip nonvolatile Flash signature arr
ay 0000H–01FFH