AT89LP51 Atmel Corporation, AT89LP51 Datasheet - Page 15

• Manufacturer Part Number: AT89LP51
• Manufacturer: Atmel Corporation

Specifications of AT89LP51

• Flash (kbytes): 4 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 36
• Uart: 1
• Sram (kbytes): 0.25
• Eeprom (bytes): 256
• Self Program Memory: IAP
• Operating Voltage (vcc): 2.4 to 5.5
• Timers: 3
• Isp: SPI
• Watchdog: Yes

3.3.1
3.3.2
3709D–MICRO–12/11
XDATA
FDATA
address space as shown in
the CPU can access them. The AT89LP51/52 includes 256 bytes of nonvolatile Flash data
memory (FDATA).
The external data memory space can accommodate up to 64KB of external memory. The
AT89LP51/52 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.
Addresses above the range implemented internally will default to XDATA. The AT89LP51/52
supports up to 63.75K or 56K bytes of external memory when using the internally mapped mem-
ories. Setting the EXRAM bit (AUXR.1) to one will force all MOVX instructions to access the
entire 64KB XDATA regardless of their address (See
page
Figure 3-6.
The Flash Data Memory is a portion of the external memory space implemented as an internal
nonvolatile data memory. Flash Data Memory is enabled by setting the DMEN bit (MEMCON.3)
to one. When IAP = 0 and DMEN = 1, the Flash Data Memory is mapped into the FDATA space,
at the bottom of the external memory address space, from 0000H to 00FFH. (See
MOVX instructions to this address range will access the internal nonvolatile memory. FDATA is
0000
FFFF
20).
(XDATA: 64KB)
EXRAM = 1 or
External Data
External Data Memory Map
DMEN = 0
IAP = 0
Section 3.3.3 on page 18
Figure
3-6. These memory spaces may require configuration before
0100
00FF
FFFF
(XDATA: 63.75KB)
External Data
(FDATA: 256)
EXRAM = 0
Flash Data
DMEN = 1
IAP = 0
for more details of the external memory
“AUXR – Auxiliary Control Register” on
2000
FFFF
1FFF
AT89LP51/52
(XDATA: 56KB)
Flash Program
External Data
(CODE: 8KB)
EXRAM = 0
DMEN = x
IAP = 1
Figure
3-6).
15