Can I do protocol (i2c) analyze by pure software

Question

Recently I was debugging a light sensor issue which connect by I2C bus. To get the original raw data, we rework the PCB to get the I2C data onto I2C analyzer. But the board is so small, so the rework process is very difficult to do. Anyway, we finish the work. But an idea come to my mind, how about to modify I2C bus driver and let it log everything into a file. We can use this log file to do the analyzer later. Is this possible? how about it on Windows (if MSFT can make a suck temporary driver).

Answer 1

I would say that this is off-topic for SO.

However, no, you cannot debug I2C purely in software; I2C problems are typically caused by the voltage levels being wrong either because the lines are not properly pulled up or because the host / slave cannot properly drive them down. It may be because of too much capacitance on the lines. In other words, they are generally analogue problems. To debug them, you need to see the actual signals, either with a debugger or an oscilloscope (preferably both).

Of course, if you have access to the source, then the bus driver can probably be modified to log to a file. This won't help you, however, when you don't see what you expect to.

So, what I'm saying is, really, that there's no getting away from soldering wires on. It's only three though.

Answer 2

An inexpensive tool that might be of use is I2CDriver. I've used it to trace DDC traffic on an I2C bus. Unfortunately, and I'd be delighted to find out I'm wrong, I do not believe it's possible to trace I2C traffic on Windows. (On Linux, this is trivial to do.)