NetBurner Community Forum

odd problem...
moving app from 5282 to 5270, and lots of board changes (argh!), and i am seeing the following.
some of my I2C devices are working OK. they have short, 1 byte, reads. others with
longer reads and/or 3-4 byte writes are having problems.
it appears that the upper nibble of the bytes coming in are good but the lower nibble is
zeros. of course, not all of the time, but consistently.
this is using the same i2c devices as on the previous board, and some new ones.
any ideas? i have an old usb logic analyzer so my sample rate isn't very high but it
looks like the clock rise times may be too slow(?).

does this ring a bell for anyone?

I found some issues with the I2C today on the MOD5234.

I was always getting lots of timeouts and only the very occasional reply from the devices on the bus. I noticed when hooked up to a logic analyser that there was no bus activity after the first 2-3 attempts. The bus just kept reporting no idle, yet both lines where inactive high.

I noticed that single stepping the I2CInit call would allow it to all start working so I inserted a 1 second delay after the I2CInit call and now everything is working. Not sure why this is but could be a hardware issue with the MCF5234 itself and the configuration of the I2C.

Either way, I can now get I2C to work with a number of devices on the same bus!

Dave...

thanks for the reply.

but the key to my problem was my statement:
"lots of board changes (argh!)"

i wasn't getting an acknowlege from a device in question.
i looked at the signals and the rise/fall times were out of
spec but that matched previous board that worked.

now why wouldn't a device give an acknowldge?
because it didn't have power or ground connected!
argh!!!