I2C Spy weird behaviour

[lokobob99]

Hello everyone,

 

I'm trying to spy on a I2C communication. For that I'm using a Time-of-Flight Sensor which measures the distance. Now while the arduino code runs perfectly fine and the measurements are shown on the serial monitor, the I2C protocol looks kind of odd and gives me the message, that samples could be lost (see picture). I also include a picture of my arduino code.

Any help would be appreciated!

Kind regards

 

 

EDIT: When I use the SDK example (Digital_I2C_Spy.py) the output looks even more strange

 

[attila]

Hi @lokobob99

For larger device buffer, go to Settings/ Device Manager and select the 4th configuration.
Try the glitch filter.

[lokobob99]

Hello attila,

thanks for the fast reply! I changed to the 4th configuration and used the glitch filter, but it still doesn't seem to help.

 

[attila]

Hi @lokobob99

Probably the average throughput is higher that the device can stream for spying.
With continuous 400kHz I2C transmission it could require up to 3.2MSps but the device supports up to about 2-4MSps depending on the available USB bandwidth, system...
You could use 100kHz I2C (or delay between transfers) to reduce the rate or use the Logic Analyzer with triggering to capture the important events like odd i2c values, NAKs...