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Morten R

Hi

I have an error that shows its ugly head now and then....
The µC I'm using is C8051F122.

When I debug I can locate the problem, but the bug does not show the same place in code all times.

What I see now is that when stepping over the following line:

SMB0CN = 0x44;

The register SMB0CN actually is set to 0xC4. This sets the BUSY bit in the register.

It can be resolved by removing the µC supply, but a RESET won't do. But after some time the problem shows again.....

Does anyone have an idea????

Best Regards....

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  • 0 in reply to Morten R

    Please note that it does makes no difference if I perform a reset by pulling the reset pin low, or if I press reset in the IDE. I see that the µC is reset but it starts with an error code indicating that I2C communication with onboard EEPROM fails. But if I turn off the supply shortly, and then let the µC startup the problem is gone.

    I'm trying to figure out what the difference is between resetting the µC and to power cycle it.

    The only thing that I can come up with is that the EEPROM is also powered down during the power cycle, but I can't see what difference that can make....

  • 0 in reply to Morten R

    I'm trying to figure out what the difference is between resetting the µC and to power cycle it.

    The difference is that only one of these resets the I2C EEPROM, too. I2C can communication get stuck if you reset the master halfway through a transaction, and then just start a new one.

  • 0 in reply to HansBernhard Broeker

    Hi Hans

    That was my theory too. But I'm not sure what how to prevent that communication is stopped halfway....

    Would it be enough to verify that the BUSY bit (SMB0CN.7) equals 0 (0=free, 1=busy)

  • 0 in reply to Morten R

    But I'm not sure what how to prevent that communication is stopped halfway....

    You quite probably can't. Reset will reset everying. Immediately. Software gets no say in what is stopped or not, once the CPU resets.

    You'll have to reset I2C communication state in the slaves somehow...