2 x ZED-F9P's on I2C bus issues

Qwiic System
1

Hi All,

I’m having issues with trying to run 2 ZED F9P’s on the same I2C bus.

Just wondering if anyone else has ran 2 on the same bus with success?

I’m using the sparkfun ZEDF9P library.

Everything runs fine for a few minutes up to an hour, then the bus crashes.

I have found the only way to stop the bus crashing is to remove the 2nd module.

I2C addresses were assigned using u-center. I have turned off everything but Nav-PVT messages on the 2nd modules I2C port. When its working I can read PVT messages fine from the 2nd module.

Interesting thing is that when I remove all code associated with the second F9P I still get the bus errors. There has to be something going on with my u-centre setup that is allowing the 2nd F9P’s I2C port to maybe send requests onto the bus.

I really need to invest in a scope hey.

Any ideas would be really appreciated.

Paul.

2

How long are your I2C/qwiic cables?

Might try shorter cables to see if it’s a problem with the I2C bus. That and cut the pullup jumpers on one of the modules, if the impedance on the bus is just low enough, you can also see the symptoms you’re experiencing.

3

Hi YellowDog,

Have made the i2c run as short as possible and tried a few different combinations of pullups. Jumpers are open.

I’ll double check everything when it comes to pullups and have another go.

Thanks for the advice.