External Flash and QSPI Settings

[Fan Jiaming]

I have tried to study the behavior of the QSPI and the external flash. I noticed that the QSPI_CONFIG_READOC and QSPI_CONFIG_WRITEOC settings in sdk_config.h cannot be set to use a higher data lines.

More specifically, the QSPI_CONFIG_READOC can only be set to Read2IO and QSPI_CONFIG_WRITEOC to PP. Anything above would cause the FATFS module to throw an error and the USB MSC to not recognize the drive (For some reasons, PP2O works on USB MSC but not FATFS).

I have set QSPI_CONFIG_SCK_DELAY to 255 and QSPI_CONFIG_FREQUENCY to 32MHz/16, so it might not be a clock issue.

Anyone succesfully use more data lines?

[Hung Bui]

Hi Fan,

Thanks for the instruction, I can see the same thing here. I reported it to the developer. will get back to you if we find something.

[Anantha Keshava]

Hung Bui,

Was there any resolution to this by the developers? I'm about to attempt a similar thing on the v15.0 with the nRF52840 Preview DK.

[Hung Bui]

I'm afraid we don't have an update on this. 

[Constantin]

Any update. With SDK 17 still the same error. Would be good to have the example running as expected or?

[Constantin]

Okay found the solution. Quiet obvious. The example for qspi enables the QSPI mode of the memory. Hence, the QSPI can be used. This is missing insde the nrf_block_dev_qspi.c inside the init routine. You have to add the following lines to started from e.g. 388:

    // Switch to qspi mode
    uint8_t temporary = 0x40;
    cinstr_cfg.opcode = QSPI_STD_CMD_WRSR;
    cinstr_cfg.length = NRF_QSPI_CINSTR_LEN_2B;
    ret = nrf_drv_qspi_cinstr_xfer(&cinstr_cfg, &temporary, NULL);
    APP_ERROR_CHECK(ret);

This will enable the QSPI of the memory chip and it is afterwards possible to used the QSPI_CONFIG_WRITEOC = 3 and QSPI_CONFIG_READOC = 4.