P87C51FA-4N NXP Semiconductors, P87C51FA-4N Datasheet - Page 19

• Manufacturer Part Number: P87C51FA-4N
• Description: IC, 8BIT MCU, 80C51, 16MHZ, DIP-40
• Manufacturer: NXP Semiconductors

Specifications of P87C51FA-4N

• Controller Family/series: 80C51
• No. Of I/o's: 32
• Ram Memory Size: 256Byte
• Cpu Speed: 16MHz
• No. Of Timers: 4
• No. Of Pwm Channels: 5
• Core Size: 8 Bit
• Program Memory Size: 8KB
• Package: 40PDIP
• Device Core: 80C51
• Family Name: 87C
• Maximum Speed: 16 MHz
• Ram Size: 256 Byte
• Operating Supply Voltage: 3.3|5 V
• Data Bus Width: 8 Bit
• Program Memory Type: EPROM
• Number Of Programmable I/os: 32
• Interface Type: UART
• Operating Temperature: 0 to 70 °C
• Number Of Timers: 3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Philips Semiconductors
Reduced EMI Mode
The AO bit (AUXR.0) in the AUXR register when set disables the
ALE output.
Reduced EMI Mode
AUXR (8EH)
AUXR.0
Dual DPTR
The dual DPTR structure (see Figure 13) enables a way to 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 that allows the program code to
switch between them.
AUXR1 (A2H)
Where:
The DPS bit status should be saved by software when switching
between DPTR0 and DPTR1.
2000 Jan 20
New Register Name: AUXR1#
SFR Address: A2H
Reset Value: xxx000x0B
DPS = AUXR1/bit0 = Switches between DPTR0 and DPTR1.
80C51 8-bit microcontroller family
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
7
–
7
–
6
–
Select Reg
6
–
DPTR0
DPTR1
AO
5
–
5
–
4
–
LPEP
4
Turns off ALE output.
WUPD
3
–
3
2
–
2
0
DPS
0
1
1
–
1
–
Back
AO
DPS
0
0
19
Note that bit 2 is not writable and is always read as a zero. This
allows the DPS bit to be quickly toggled simply by executing an INC
DPTR insstruction without affecting the WOPD or LPEP bits.
DPTR Instructions
The instructions that refer to DPTR refer to the data pointer that is
currently selected using the AUXR1/bit 0 register. The six
instructions that use the DPTR are as follows:
The data pointer can be accessed on a byte-by-byte basis by
specifying the low or high byte in an instruction which accesses the
SFRs. See application note AN458 for more details.
Next
INC DPTR
MOV DPTR, #data16
MOV A, @ A+DPTR
MOVX A, @ DPTR
MOVX @ DPTR , A
JMP @ A + DPTR
AUXR1
DPS
BIT0
(83H)
DPH
Increments the data pointer by 1
Loads the DPTR with a 16-bit constant
Move code byte relative to DPTR to ACC
Move external RAM (16-bit address) to
ACC
Move ACC to external RAM (16-bit
address)
Jump indirect relative to DPTR
80C51/87C51/80C31
Figure 13.
(82H)
DPL
DPTR1
DPTR0
Product specification
EXTERNAL
MEMORY
DATA
SU00745A