Parallel port output

Question

I have a small board that controls some appliances through the parallel port.

What i want to do is to put on high/low pin X with out modifying the rest of the pins (short story, control each pin individuality)

Example: D0-D5 = 1 what i want D0 = 0 and D1-D5 = 1

Thanks a lot.

Answer 1

Usually in this situation I keep a variable with the whole byte, change the bits I want and then write it back to the port.

Example in C:

PortValue = 0x00;    // Set all bits to 0
LPT = PortValue;

PortValue |= 0x01;   // Set the bit 0 to 1
LPT = PortValue;

PortValue &= ~0x01;  // Set the bit 0 to 0
LPT = PortValue;