Continue to Site

Welcome to

Welcome to our site! is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

difference between I2C PAD and GPIO PAD

Not open for further replies.


Full Member level 2
Jul 21, 2006
Reaction score
Trophy points
Activity points
In SoC chip, what is difference between I2C PAD and GPIO PAD?

I know that -
I2C PAD is special pad which is not GPIO.
there will be pullup on these PADS.

But would like to know the insights. Did my homework, but no success...

So asking you, can you please share your insights? Thanks..

Are you referring to a specific SoC?

Most microcontroller have I2C as second function of a GPIO pin which clarifies that I2C functionality can be covered by a usual GPIO. It's imply done by configuring the GPIO as open drain output. Pull-up resistors are usually added externally, in case of a short I2C bus with low load capacitance, an internal pull-up resistor might be sufficient.

Interested in this question too...

So you mean to say that the internal/external presence of pull-up resistors in I2C will depends completely on the SoC used. The SoCs which do not have this feature, external pull-ups have to be placed and this can drive higher loads.

External pull-ups are the standard according to I2C specification and should be always provided in a design to be aon the safe side.

Well the I2C standard required (dependent of the mode) to have a low-pass filter, the pull-up could be internally or externally.

In our design the GPIO pad has the same functionality as the I2C pad, I means, pull up/down value controllable, low pass filter controllable, Schmitt trigger controllable, drive strength controllable.

Ones a general purpose io pin, whereas the other is a serial bus method of communication. By stating it's an I2C pad the manufacture is telling you...the customer that it meets the I2C standards.

For example I2C standard requires certain properties, "I²C uses only two bidirectional open-drain lines, Serial Data Line (SDA) and Serial Clock Line (SCL), pulled up with resistors. Typical voltages used are +5 V or +3.3 V although systems with other voltages are permitted." - wiki

You'll find gpio pads also are separated into banks that operate at different voltage standards etc.

Not open for further replies.

Part and Inventory Search

Welcome to