AT89LP51RB2 Atmel Corporation, AT89LP51RB2 Datasheet - Page 17

• Manufacturer Part Number: AT89LP51RB2
• Manufacturer: Atmel Corporation

Specifications of AT89LP51RB2

• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 42
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Adc Channels: 7
• Adc Resolution (bits): 10
• Adc Speed (ksps): 153.8
• Sram (kbytes): 1.375
• Self Program Memory: API
• Operating Voltage (vcc): 2.4 to 5.5
• Timers: 4
• Isp: SPI/OCD/UART
• Watchdog: Yes

3.3
3.3.1
3722A–MICRO–10/11
External Data Memory
XDATA
AT89LP microcontrollers support a 16-bit external memory address space for up to 64K bytes of
external data memory (XDATA). The external memory space is accessed with the MOVX
instructions. Some internal data memory resources are mapped into portions of the external
address space as shown in
the CPU can access them. The AT89LP51RB2/RC2/IC2 includes 1152 bytes of on-chip Extra
RAM (EDATA).
The external data memory space can accommodate up to 64KB of external memory. The
AT89LP51RB2/RC2/IC2 uses the standard 8051 external data memory interface with the upper
address byte on Port 2, the lower address byte and data in/out multiplexed on Port 0, and the
ALE, RD and WR strobes. XDATA can be accessed with both 16-bit (MOVX @DPTR) and 8-bit
(MOVX @Ri) addresses. See
interface.
Some internal data memory spaces are mapped into portions of the XDATA address space. In
this case the lower address ranges will access internal resources instead of external memory.
A d d r e s s e s a b o v e t h e r a n g e i m p l e m e n t e d i n t e r na l l y w i l l d e f a u l t t o X D A TA . T h e
AT89LP51RB2/RC2/IC2 supports up to 60–62K bytes of external memory when using the inter-
nally mapped memories. Setting the EXTRAM bit (AUXR.1) to one will force all MOVX
instructions to access the entire 64KB XDATA regardless of their address (See
iary Control Register” on page
Figure 3-6.
0000
FFFF
External Data Memory Map
(XDATA: 64KB)
External Data
EXRAM = 1
XRS = x
FPS = x
Figure
AT89LP51RB2/RC2/IC2 Preliminary
Section 3.3.2 on page 18
19).
3-6. These memory spaces may require configuration before
0400
03FF
FFFF
(XDATA: 62KB)
External Data
(EDATA: 1KB)
XRS = 011B
EXRAM = 0
Extra RAM
FPS = 0
for more details of the external memory
7FFF
Flash Program
(CODE: 32KB)
EXRAM = 0
XRS = x
FPS = 1
“AUXR – Auxil-
17