8051 Programming

8051 have four ports

• They are Port 0, Port 1, Port 2, Port 3.
• 8051 is a 8bit.
• Port pins can be access by.
  • Bit instruction.
  • Byte instruction.

Bit instruction

• In bit instruction each port pins value assigned individually.
• In port0 3rd pin should keep high and 4th pin should keep low it can be done by this way.
• Example
  • P0_3=1; (High) // Port 0 3rd pin:
  • P0_4=0; (Low) // Port 0 4th pin:

Byte instruction

• Byte instruction is use to access entire port pins.

 Example 
   In port 0 all pin should keep low. 
   P0=0x00;
   0x0000|0000;
   0x 0  | 0 = 0x00.
   In port 0 MSB should be high and LSB should be low
   P0=0xF0;
      0x1111|0000;
      0x F  | 0 = 0xF0.

Binary Table

Byte Instruction