Rainbow Electronics AT89LP216 - Manual (Page 7)

7
3621A–MICRO–6/06
AT89LP216 [Preliminary]
The Atmel Signature Array is initialized with the Device ID in the factory. The User Signature
Array is available for user identification codes or constant parameter data. Data stored in the sig-
nature array is not secure. Security bits will disable writes to the array; however, reads are
always allowed.
6.2 Data Memory
The AT89LP216 contains 128 bytes of general SRAM data memory plus 128 bytes of I/O mem-
ory mapped into a single 8-bit address space. The 128 bytes of data memory may be accessed
through both direct and indirect addressing of the lower 128 byte addresses. The 128 bytes of
I/O memory reside in the upper 128-byte address space (
Figure 6-2 ). The I/O memory can only
be accessed through direct addressing and contains the Special Function Registers (SFRs).
Indirect accesses to the upper 128-byte addresses will return invalid data. The lowest 32 bytes
of data memory are grouped into 4 banks of 8 registers each. The RS0 and RS1 bits (PSW.3
and PSW.4) select which register bank is in use. Instructions using register addressing will only
access the currently specified bank. The AT89LP216 does not support external data memory.
Figure 6-2. Data Memory Map
Table 6-1. AUXR1 – Auxiliary Register 1
AUXR1 = A2H Reset Value = XXXX 0XXXB
Not Bit Addressable
– – – – SIGEN – – –
Bit 7 6 5 4 3 2 1 0
FFH
UPPER
128
80H
7F H
LO WER
128
0
Accessible
By Direct
Addressing
Only
Accessible
By Direct
and Indirect
Addressing
Only
Special Function
Registers
Ports
Status and Control Bits
Timers
Registers
Stack Pointer
Accumulator
(Etc.)