I have succesfully made a connection with a PSoc 4200 as a I2C slave with a McMod110 even at 400kHz
But now I want to use the McDevelopment board it doesn't work any more.
I can see there are 2 LED's placed on that bus. So I presume the signal is BUFFERED and no pull-up resistors are used.
When I use my Digital scope to analyze what's on the I2C bus, I got a NACK.
But when I look on my analog scope I only see a noisy signals of around 0,5 Volts on SCL and around 200 milliVolts for SDA, clearly no pull-ups.
So I tried to add pull-up resistors, I tried everything 10k, 4k7, 2k2, 1k. I can see the signal improving by scope from 10k to 4k7, but at 1k I don't see much difference, the slope from the buffer is to slow I guess, even at 100kHz. I will try tommorow with lower frequencies because I think the buffer doesn't support high frequencies. Or is it safe to put lower value resistors?
[SOLVED] Read reply for this incredible story.