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@ Bad Steve -

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We did a quick test on your board, and we found that the problem can be I2C master. There is no stop condition, unless my analyzer is wrong.

Although ALFAT does support repeat start condition well, but I personally think that your I2C signal is not good, at least, strange with me.

Although you can read write from I2C, but these bad signals put ALFAT in wrong state, that is why ALFAT can not work as expected.

So, please check your code and correct your I2C master. If it is corrected, it should work fine.

Also, your I2C speed is quite high, it is about 460KHz, it should be smaller than 400KHz. It can work now but so far, if it is higher traffic, there can be more problems happen. But this is another story.

Below is our EMX master and your master I2C signal.

Let us know if we can help more.


Thanks for the info. I am not an I2C guru, but there are STOP commands in my code. I can send you the code if you like. Could you please tell me what I am looking at in the images that you sent. At what point in the code is that? Why do I not see any SCL activity? The frequency is all based off of the microchip setup, which I will check again and can probably lower to say 100Khz. Will the Alfat work at that speed?


@ Bad Steve -

There something wrong in your code so it could not generate STOP condition.

In the analyzer, the STOP condition will be in RED, START condition will be in GREEN. As you see, on our board, we have START and STOP. But your board, it doesn’t show up.

About the speed, the analyzer is showing me about 460Khz. Not 100KHz.

ALFAT work fine if smaller than 400KHz, so 100 is good.
That is all I see in my analyzer. I can capture again in case you want to see them.

You don’t see SCL because it is scaled, you will see it if I zoom it out.

Even sometime, in idle state, I see the SDA is high and SCL is slow. This is really bad as I know.

Is there any pull up resistors for these 2 pins? I don’t see it in your board, but I don’t know about your micro processor these resistors are required or not. Usually, they are needed, as I know.