i2c and parallel port pin state

K

kuntul

New Member

• Dec 14, 2009

• #1

Is all of these possible states for i2c lines? Which are possible for parallel port pin?

Pulled to vdd
Pulled to ground
Tristate
Pulled to -vdd

I know that pulled to ground is true... not sure about the others. I think that pulled to vdd is wrong... the pull up resistor does that??

 

Sceadwian

Banned

• Dec 14, 2009

• #2

https://en.wikipedia.org/wiki/Parallel_portIf I'm not mistaken outputs can be either tied high or low, inputs are tri-stated but with a weak pullup or down possibly. High speed parallel ports probably don't have pullup/downs

 

Last edited: Dec 14, 2009

K

kuntul

New Member

• Dec 14, 2009

• #3

so then what is wrong here is pulled to ground, everything is correct?

 

P

Pommie

Well-Known Member

Most Helpful Member

• Dec 14, 2009

• #4

The I²C bus has only two states, driven low by the output or pulled high by an external pullup. The bus should never be driven high as this prevents other devices pulling it low.

Mike.

 

Last edited: Dec 14, 2009

K

kuntul

New Member

• Dec 14, 2009

• #5

so I2C is pulled to vdd and pulled to -vdd and the parallel port pin pulled to vdd, pulled to -vdd and tristate... is this correct?

 

P

Pommie

Well-Known Member

Most Helpful Member

• Dec 14, 2009

• #6

No, I²C is pulled to Vdd or driven to ground. There are no negative voltages involved. Parallel ports are driven to Vdd or driven to ground.

I'll correct my original post.

Mike.

 

Last edited: Dec 14, 2009

K

kuntul

New Member

• Dec 14, 2009

• #7

a parallel port pin can also have analog output? and no tristate?

 

Sceadwian

Banned

• Dec 14, 2009

• #8

analog output? No, where did you read that?

 

K

kuntul

New Member

• Dec 14, 2009

• #9

I was asking if it's true..... not a statement