AT87C51RC2-3CSUM Atmel, AT87C51RC2-3CSUM Datasheet - Page 15

• Manufacturer Part Number: AT87C51RC2-3CSUM
• Description: IC 8051 MCU 32K OTP 40MHZ 40DIP
• Manufacturer: Atmel
• Series: 87Cr

Specifications of AT87C51RC2-3CSUM

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 40/20MHz
• Connectivity: UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: OTP
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -

5.4
Figure 5-3.
4188F–8051–01/08
Dual Data Pointer Register
7
Use of Dual Pointer
AUXR1(A2H)
The additional data pointer can be used to speed up code execution and reduce code size in a
number of ways.
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/bit0
them (Refer to Figure 5-3).
Table 5-3.
1.
GF3 will not be available on first version of the RC devices.
Address 0A2H
Symbol
AUXR1
DPS
DPS
GF3
0
-
User software should not write 1s to reserved bits. These bits may be used in future 8051 family
products to invoke new feature. In that case, the reset value of the new bit will be 0, and its
active value will be 1. The value read from a reserved bit is indeterminate.
AUXR1: Auxiliary Register 1
Function
Not implemented, reserved for future use
Data Pointer Selection.
This bit is a general purpose user flag
DPH(83H) DPL(82H)
Reset value
DPS
0
1
DPTR1
Operating Mode
DPTR0 Selected
DPTR1 Selected
DPTR0
(Table
X
-
5-3) that allows the program code to switch between
X
-
(2)
.
(1)
X
-
X
-
External Data Memory
AT/TS8xC51Rx2
GF3
0
X
-
X
-
DPS
0
15