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Variability in UART output on startup



Hello,

We are in the process of creating an auto-loader for an empty flash device using a design similar to the Beagle Bone Black. Generally, if we try to boot a system with an empty EEPROM we will get an error message stating Incorrect magic number (all Fs) in EEPROM / Could not get board ID. Currently, we can get by this bypassing the EEPROM check and manually writing the values to EEPROM over i2c in u-boot. However, in the process of trying to automate this process, we have experienced some issues that aren't making sense. Occasionally, our system will boot from the SD card and error out after initially entering into u-boot. We have noticed that this occurs when the output without a SD card present ('C' characters) is much faster than normal (when everything boot and we can exit into u-boot). Could you offer some input on what may be occurring in this case? It is not persistent as we have been able to return to normal after a couple of power cycles.

Thanks,

Tony

  • Hi,

    Tony Kunkel said:
    We have noticed that this occurs when the output without a SD card present ('C' characters) is much faster than normal (when everything boot and we can exit into u-boot).

    This is not a normal behavior. Please provide more detailed information about your hardware and the software you use.