8 reset, Memory organization, 1 program memory – Rainbow Electronics AT89LP216 User Manual
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AT89LP216 [Preliminary]
5.8
Reset
The RST pin of the AT89LP216 is active-low as compared with the active high reset in the stan-
dard 8051. In addition, the RST pin is sampled every clock cycle and must be held low for a
minimum of two clock cycles, instead of 24 clock cycles, to be recognized as a valid reset.
6.
Memory Organization
The AT89LP216 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 up to
64K bytes of directly addressable application code. The data memory has 128 bytes of internal
RAM and 128 bytes of Special Function Register I/O space. The AT89LP216 does not support
external data memory or external program memory.
6.1
Program Memory
The AT89LP216 contains 2K bytes of on-chip In-System Programmable Flash memory for
program storage. The Flash memory has an endurance of at least 10,000 write/erase cycles and
a minimum data retention time of 10 years. The reset and interrupt vectors are located within the
first 59 bytes of program memory (refer to
). Constant tables can be allo-
cated within the entire 2K program memory address space for access by the MOVC instruction.
The AT89LP216 does not support external program memory.
Figure 6-1.
Program Memory Map
A map of the AT89LP216 program memory is shown in
. In addition to the 2K code
space from 0000h to 07FFh, the AT89LP216 also supports a 64-byte User Signature Array and
a 32-byte Atmel Signature Array that are accessible by the CPU in a read-only fashion. In order
to read from the signature arrays, the SIGEN bit in AUXR1 must be set. While SIGEN is one,
MOVC A,@A+DPTR will access the signature arrays. The User Signature Array is mapped to
addresses 0040h to 007Fh and the Atmel Signature Array is mapped to addresses 0000h to
001Fh. SIGEN must be cleared before using MOVC to access the code memory.
Program Memory
0000
07FF
0000
001F
User Signature Array
0040
007F
Atmel Signature Array