Pic 12f629

[Bruce]

I'm a sucker for simplicity.

Try this;

GPIO.4 ----/\/\/\---|<|----+5V.
                    LED

             10K
GPIO.0 --|--/\/\/\---+5V
         |--switch---GND.

When you press the switch it grounds GPIO.0.

@ device  pic12F629, intrc_osc_noclkout, wdt_on, mclr_off, protect_off

    DEFINE OSCCAL_1K 1
    DEFINE OSC 4
    
    RELAY VAR GPIO.4   ' relay output
    Pswitch VAR GPIO.0 ' switch input

    TRISIO = %00000001 ' GPIO.0 input, rest outputs
    WPU = 0            ' input pull-ups disabled
    CMCON = 7          ' disable comparators
    PAUSE 10           ' POR delay
    
MAIN:
    RELAY = ! Pswitch ' Relay pin = the opposite of Psiwtch pin    
    GOTO MAIN
    END

Does this work?

[Darrel Taylor]

Switch to ground. Definately the better way to go.

I might suggest a different Main loop though.

MAIN:
    IF RELAY = Pswitch THEN
        RELAY = ! Pswitch ' Relay pin = the opposite of Pswitch pin    
    ENDIF
    PAUSE 20
    GOTO MAIN

    END

Those pesky R-M-W's
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[runrite]

Hi all out there
The last time I did a 8 pin pic was 10 years ago
The problem was to do with the weak pull up
I really want to thank all out there
Bye for now

[sayzer]

Switch to ground. Definately the better way to go.

I might suggest a different Main loop though.

MAIN:
    IF RELAY = Pswitch THEN
        RELAY = ! Pswitch ' Relay pin = the opposite of Pswitch pin    
    ENDIF
    PAUSE 20
    GOTO MAIN

    END

Those pesky R-M-W's
<br>

Darrel,

I just want to learn;

Is it really a safe way to read the status of an output pin?

Thanks

[mister_e]

Yes, in fact, from my understanding, it reads the content of the output-latch.

[Darrel Taylor]

Is it really a safe way to read the status of an output pin?

Is it safe?

Well, as far as doing damage, it's perfectly "Safe".
In fact the chip "reads" the state of the OUTPUT pin, everytime you you change the state of any pin on the same port.

The only un-safe part, is if you don't take the R-M-W problems into account.
Can really mess with the program.
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