AT89LP428 datasheet(10/149 Pages) ATMEL

10 / 149 page

3654A–MICRO–8/09

AT89LP428/828

In order to read from the signature arrays, the SIGEN bit (DPCF.3) must be set. While SIGEN is

one, MOVC A,@A+DPTR will access the signature arrays. The User Signature Array is mapped

from addresses 0080H to 00FFH and the Atmel Signature Array is mapped from addresses

0000H to 003FH. SIGEN must be cleared before using MOVC to access the code memory. The

User Signature Array may also be modified by the In-Application Programming interface. When

IAP = 1 and SIGEN = 1, MOVX @DPTR instructions will access the array.

3.2

Internal Data Memory

The AT89LP428/828 contains 256 bytes of general SRAM data memory plus 128 bytes of I/O

memory mapped into a single 8-bit address space. Access to the internal data memory does not

require any configuration. The internal data memory has three address spaces: DATA, IDATA

and SFR; as shown in Figure 3-2.

Figure 3-2.

Internal Data Memory Map

3.2.1

DATA

The first 128 bytes of RAM are directly addressable by an 8-bit address (00H - 7FH) included in

the instruction. 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. Instruc-

tions using register addressing will only access the currently specified bank.

3.2.2

IDATA

The full 256 bytes of internal RAM can be indirectly addressed using the 8-bit pointers R0 and

R1. The first 128 bytes of IDATA include the DATA space. The hardware stack is also located in

the IDATA space.

3.2.3

SFR

The upper 128 direct addresses (80H - FFH) access the I/O registers. I/O registers on AT89LP

devices are referred to as Special Function Registers. The SFRs can only be accessed through

direct addressing. All SFR locations are not implemented. See “Special Function Registers” on

page 15.

FFH

Upper

128

80H

7F H

Lower

128

FFH

80H

Special

Function

Registers

Ports

Status and Control Bits

Registers

Stack Pointer

Accumulator

(Etc.)

Timers

Accessible

by Indirect

Addressing

Only

Accessible

by Direct and

Indirect Addressing

Only

Accessible

by Direct

Addressing

IDATA

SFR

DATA/IDATA

AT89LP428 Arkusz danych(PDF) 10 Page - ATMEL Corporation

AT89LP428 Arkusz danych(HTML) 10 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Arkusz danych Pobierz

Link URL