question about PIC's port

[clayofjunk]

Forgive me if my question sounds amatuer but i needed an answer.

With referrence to the below diagram, note that PortB is initialized as an output port.
Consider this, in my firmware I will send a HIGH transition to PortB0 and a LOW to PortB1.
Incidently PortB0 is accidently shorted to PortB1 as shown below.
Will PortB0 be pulled down to LOW as well, because of the sinking from PortB1?

 

[samcheetah]

i dont think that the output of B1 will effect B0. both are configured for output and both of them have an output available. maybe it would damage the PIC.

 

[hugo]

Hi,

Are you conecting physically portb.0 and portb.1?
If the answer is yes that's a short-circuit and could damage the PIC !
Anyway you can connect portb.0 and portb.1 through a resistor (10k) if you really want that!!!

Bye

 

[IanP]

No, this will not damage your PIC, and P0 should pull down P1 so they both will be at Low level. In most cases the outputs use very week pull-up resistors (in reality they are not resistors but MOSFET transistors) of approximate value between 20-50k and the Voh current will be in uA and the Vol current will be in mA.
According to the aboce you can safeky shorten each output to 0V line but it is not safe if it is shorten to +V !!!

 

[clayofjunk]

I think IanP has a point, no offense to hugo and samcheetah.

but i do have one question what is Voh and Vol.
probably u can give a link to read about it.

 

[clayofjunk]

i found it the below diagram would explain what VOH and VOL

 

[samcheetah]

I think IanP has a point, no offense to hugo and samcheetah

its alright. i agree with IanP. i think i was relating your question to another problem i had in the past. anyway, thanx IanP.

 

[C-Man]

No, this will not damage your PIC, and P0 should pull down P1 so they both will be at Low level. In most cases the outputs use very week pull-up resistors (in reality they are not resistors but MOSFET transistors) of approximate value between 20-50k and the Voh current will be in uA and the Vol current will be in mA.
According to the aboce you can safeky shorten each output to 0V line but it is not safe if it is shorten to +V !!!

I do not agree with you. This would be true with an 8051 but not with a PIC.

The PIC can source and sink 20 to 25 mA per pin. As far as I know the outputs are short circuit protected but this condition is no good at all. If possible avoid such configurations.

best regards