i2C pull up calc

i read that in order to use i2c i need external pull ups

how do i calc the resistor value for sda and scl ?

As Hugo has stated before… I2C isn’t horribly picky. I know that others have used 4.7K, and I have successfully used 10K resistors. You need an oscilloscope to look at the signal, but I would say start with 10k and see what happens.