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Topic: I2C bus "problems" (Read 3 times) previous topic - next topic

lost_and_confused

Amazing!

It is working!

Alas I am biased to use the centipede library.

The code is already in my sketch and I have nearly written most of the stuff for what I wanted to do.

But I shall keep it in the reserves.


Grumpy_Mike

Well done.  :)

I always find when I find a mistake I feel a mixture of elation and being down for not spotting it much earlier. It happens to us all.

lost_and_confused

Yeah, thanks Grumpy.


One thing now which I have noticed:

Originally the unit has its own power supply and is plugged in to "the mains".

Programming the Arduino meant I unplugged it and plugged the USB cable into the unit and flashed it.
Doing so, I could "test" it because the Arduino would boot.

Now with the MCP and the PULL UP resistors, nothing happens.  To test the sketch I need the until fully plugged in and powered.

Bit annoying.

Is this because of the pull up resistors?  Before I had them in, with the I2C bus connected at initial testing, I am sure the Arduino worked.


Grumpy_Mike

Quote
Is this because of the pull up resistors?

No I can''t see how it could be.
If you have separate 5V supplies on the I2C device and the arduino you would have to make sure that both were powered when you plug in either USB or mains.

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