I’m using the serial lines for debug consoles on two different pieces of hardware that are connecting to each other over USB-C. Most of the serial activity is status logging from the two systems with the very occasional manual debug command. But what could be more interesting is looking at the serial data and the I2C data. There is a strong correlation between the serial log data and the I2C activity. In the capture I posted the PLC device sends a logged, but unseen, device capabilities message to the FES device which results in a burst of I2C activity. A meta analyser that could work with PLC Tx traffic and either the I2C traffic, or the I2C PD (HLA) traffic would allow things like response time measurement between the two systems.
Mixing in edge detection on INT_N (the interrupt line related to the I2C) would be really useful too. That would allow interrupt response time to be measured and provide information about system performance.
For this particular system there are 6 USB-C ports on the PLC device with multiple large complicated state machines that interact with each other for each port. On top of that the power for the ports is managed by a supervisor and there is an Ethernet port running IEEE-1588 precision time sync protocol in there somewhere as well. I’m going to be interested in that sort of performance measurement fairly soon!
I’m happy to provide you with more captures of a similar sort. I could drop them in a Google Drive folder and share that, or somewhere else that works for you. I’m kinda anti Dropbox, but could use that if pressed.