I2C Communication Problems (SDA Waveform)

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purion
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I2C Communication Problems (SDA Waveform)

Unread post by purion » Fri Nov 15, 2019 2:48 pm

I am controlling the module via I2C communication. But I noticed that some orders were ignored.
So I took a waveform with an oscilloscope. As a result, they found noise in the middle of the SDA waveform.
I want to check if this is a problem with my board or driver.


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odroid
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Re: I2C Communication Problems (SDA Waveform)

Unread post by odroid » Sat Nov 16, 2019 11:13 am

Do you use the Shifter-Shield?
Or other level-shifter something like this?
https://www.hardkernel.com/shop/level-s ... v-to-3-3v/

What is the value of the pull-up resistors on the I2C bus?

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Re: I2C Communication Problems (SDA Waveform)

Unread post by purion » Mon Nov 18, 2019 9:51 am

I'm currently not using a level-shifter.
Is level-shifter required for i2c communication?
I use direct communication. Should I put a pull-up resistor in this case?

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Re: I2C Communication Problems (SDA Waveform)

Unread post by odroid » Mon Nov 18, 2019 11:35 am

If your I2C device can work with 1.8Volt power supply, you don't need a level-shifter.
You need two pull-up resistors on SDA and SCL on I2C interface.

Which devices are you trying to connect to I2C bus?

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Re: I2C Communication Problems (SDA Waveform)

Unread post by purion » Mon Nov 18, 2019 2:05 pm

I connected the I2C bus with relay switch module(Circuit's register control).
I think it will be solved by attaching pull-up resistance. Thank you for the advice.

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Re: I2C Communication Problems (SDA Waveform)

Unread post by odroid » Mon Nov 18, 2019 3:43 pm

If the module IO voltage level is not 1.8Vol, you will fry your XU4 board.

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