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DRA744: Probability of SPI communication failure during uboot stage

Part Number: DRA744
Other Parts Discussed in Thread: DRA750

We are connected to the NOR flash chip in SPI, and there is a probability that data cannot be read during the UBoot stage.

Before measuring the waveform, it was found that there was no waveform in CS before sending the cmd. May I ask what is the reason for this situation?

  • Hi,

    Can you answer the below questions:

    • Is this a custom board?
    • What software is running ?

    Best Regards,

    Keerthy 

  • We are using the reference design of DRA750, and the spi part has not been modified to be exactly the same, running on a Linux system



    Regarding this issue, our recent analysis is

    SOC continuously sends cmd, and from the second start, there will be no change in cs, and it seems that if the peripheral does not detect the change in cs, it is considered an invalid signal.



    Can we enable SOC to trigger every cs in the case of continuous cmd? 

  • Hi,

    Are you getting any logs form U-Boot stage?
    Also is this a consistent failure or it fails sometimes and passes sometimes?

    - Keerthy

  • There is a high probability of failure.

    Our requirement is to obtain data on SPI NOR flash.

    In the uboot stage, when calling spi_flash_probe and spi_flash_read
     interface, the return value is not incorrect, but there is no data for miso. Later, it was confirmed that there was no change in cs before issuing the command, and the slave machine considered it to be an invalid command.

    It should be that after reading the ID in the probe, the cmd will be sent immediately, so CS has no further control. 

  • Hi,

    In U-Boot does sf probe work correctly?

    Does it detect the flash part correctly?

    Can you share the output?

    Best Regards,

    Keerthy 

  • If staying in the uboot stage, the sf probe is normal, including reading and writing, as follows

    U-Boot# sf probe 0
    SF: Detected W25Q32BV with page size 256 Bytes, erase size 4 KiB, total 4 MiB, mapped at 5c000000
    U-Boot# 

  • Hi,

    Can you try to write the data at U-Boot prompt?

    Since sf probe read and write are working?

    Best Regards,

    Keerthy