AT89C51RE2 Atmel Corporation, AT89C51RE2 Datasheet - Page 18

• Manufacturer Part Number: AT89C51RE2
• Manufacturer: Atmel Corporation

Specifications of AT89C51RE2

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 60 MHz
• Cpu: 8051-12C
• Max I/o Pins: 34
• Spi: 1
• Uart: 2
• Sram (kbytes): 8.25
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART/OCD
• Watchdog: Yes

Dual Data
Pointer Register
DPTR
Figure 4. Use of Dual Pointer
18
AT89C51RE2
7
AUXR1(A2H)
The additional data pointer can be used to speed up code execution and reduce code size.
The dual DPTR structure is a way by which the chip will specify the address of an external data
memory location. There are two 16-bit DPTR registers that address the external memory, and a
single bit called DPS = AUXR1.0 (see Table 17) that allows the program code to switch between
them (Refer to Figure 4).
DPS
0
DPH(83H) DPL(82H)
DPTR1
DPTR0
External Data Memory
7663E–8051–10/08