682Views13Replies

Author Options:

how do use i2c on arduino with out pull-up ? Answered

Comments

The forums are retiring in 2021 and are now closed for new topics and comments.
0
steveastrouk
steveastrouk

9 years ago

You're using the onboard TWI aren't you ?

0
act casual
act casual

Answer 9 years ago

Yes, i am.

0
steveastrouk
steveastrouk

Answer 9 years ago

Good. In that case, you can usually get away with the default port settings, but I recommend that you add an external pullup as well. The internal one is pretty weak.

0
act casual
act casual

Answer 9 years ago

how do it

0
steveastrouk
steveastrouk

Answer 9 years ago

External pull up ? What frequency are you intending to work at ?

0
act casual
act casual

Answer 9 years ago

sorry i read it wrongly
thank you

0
act casual
act casual

Answer 9 years ago

I'm not using picaxes I'm using arduino

0
rickharris
rickharris

Answer 9 years ago

Yes I know, BUT the principles are the same - This is a fairly good explanation of what it is all about.

0
steveastrouk
steveastrouk

9 years ago

You don't set the pull up/downs in the output mode on an AVR, you can only do it for input mode.

0
iceng
iceng

Answer 9 years ago

+1
Output means a pin on a digital IC like a Pic, Arduino or AVR
is FORCED High or low by an internal process and a "pull up"
is non sequitur  when compared to a Real output pin.

Of course you could be thinking of an open collector output like some
sensors that need a pull up resistor.

That does not occur ever in the land of micro-processors :-)

A

0
steveastrouk
steveastrouk

Answer 9 years ago

Ermm. Some of the LPC series have that very functionality - configurably

0
iceng
iceng

Answer 9 years ago

Didn't know that.......... Really...,  open collectors..........

Now I have to apologize to .act casual.

0
rickharris
rickharris

9 years ago

The pull up resistor is a passive device. In general outputs don't have a pull up they are active pins and will be high low or high impedance.

Can you explain in more detail what your trying to do - Circuit diagrams help.