Re: i2c/twi wiring trouble?

Hello, I have problem with I2C bus. This is first time trying to use I2C. I connected arduino nano to ADUM1250 I2C isolator, using 10k pull up resistors. But I don’t see any signal or clock over my 20mhz oscilloscope, I only see noise in mV range. I attach some photos from signal lines. One photo is arduino connected to adum using 10k pull up resistors, and other is with 1.1nF capacitor between SDA and ground. Then I connect that capacitor SCL signal seems normal, but data signal to slow and to low level. Photo with signals is 2V/division.

Sorry for bad English.
Thank you.

Do you have pull-ups on both sides of the isolator? What kind of device do you have on the side opposite to the Arduino?

I guess it's best to post a wiring diagram of your setup. Please also post the code you're using for these tests.

I just connected arduino to isolator, I do not connect other side yet. Maybe this is the problem… I will connect es9018k2m dac to it. I will try to connect and post results. I attach code in text file.

Arduino code.txt (63.8 KB)

Connected other side of isolator, and get same results. It is some problem with arduino I guess. I will try to use arduino nano tomorow.

I'm still waiting for the wiring diagram.

Sorry pylon, I only now try to connect to arduino nano instead of uno r3. And now see that everything works good, but I still can't see any I2C signal on 20mhz oscilloscope. But until it works good, I don't care anymore. Thank you for trying to help. It was my fault that I firstly try to see signal and only now try to connect to dac and try to see if it works.