Accessing individual pins simultaneously ?

[ysaacb]

1.-How can I modify some spare pins in an a specific port in one instruction cycle, without modifying the other pins?, for example: how to output low the pins 1,2,4 of the Portb in one instruction without affecting the rest?
In assembly could be done by masking the bits, but how in C?
2.- Anybody knows why the PORT B cant drive a "74HC"

Thanks

Ysaac

[SherpaDoug]

You can AND, OR or XOR the port data register. That will change multiple pins of a port in a single clock cycle.
Port B can certainly drive HC logic as well as any other port. Are both the HC and the PIC running from the same VCC?
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[ysaacb]

[Wayne_]

Portb &= 0xF4; // Will set pins 1,2,4 to low with out altering the others

Current status 10010111
Mask 11110100
New status 10010100

Portb |= 0x0F; // Will set pins 1,2,3,4 and not change pins 5,6,7,8

Current status 10010111
Mask 00001111
New status 10011111

[Guest]

thanks Wayne

I supose the preniously it's necesary to define the adress of PORTB

i.e. #byte PORTB 0xF81 (for the PIC18F4620)

Rigth?