Is Errata 109 occurrence related to SPI frequency?

[Kyle Krueger]

I have been having issues with our Flash component (S25FL256S) over SPI with the nRF52832 using easyDMA. When reading out values of a peripheral, the returned contents are sometimes empty. This has been seen very often when using a low SPI frequency (256 kHz), and much less frequently at 8 MHz.

We init the flash with the nrf_drv_spi abstraction layer.

nrf_gpio_cfg_output( FLASHMEM_CS );
nrf_gpio_pin_set( FLASHMEM_CS );

nrf_delay_ms( 100 );

nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;

spi_config.ss_pin   = FLASHMEM_CS;
spi_config.miso_pin = FLASHMEM_SDO;
spi_config.mosi_pin = FLASHMEM_SDI;
spi_config.sck_pin  = FLASHMEM_SCK;
spi_config.frequency = NRF_DRV_SPI_FREQ_8M;

spi_config.irq_priority = SPI_DEFAULT_CONFIG_IRQ_PRIORITY;

spi_config.bit_order = NRF_SPI_BIT_ORDER_MSB_FIRST;
spi_config.mode = NRF_SPI_MODE_0;  //CPHA = 0 CPOL = 0
LOG_FLASH( "Trying to init SPI\n" );
ret_code_t ret_code =  nrf_drv_spi_init( &spi, &spi_config, spi_event_handler, NULL /* p_context  */ );
LOG_FLASH( "nrf_drv_spi_init - ret_code %d\n", ret_code );
APP_ERROR_CHECK( ret_code );

and are making our spi calls through a function to abstrtact the nrf_drv_spi_transfer command

static bool spiXfer( spi_cmd_t * spiCmd ) {
    uint32_t rxLength = 0;
    ret_code_t ret_code;

    // if queue empty, return
    if ( spiCmd == &CUSTOM__EMPTY_SPI_CMD) return true;

    memset( spi_rx_buf, 0, CUSTOM__SPI_BFF_SIZE );

    logSpiCmdDetails(spiCmd);

    // nordic uses a shift buffer, rx must be length of tx+rx
    if(spiCmd->rxLength){
        rxLength += spiCmd->txLength;
        rxLength += spiCmd->rxLength;
    }

    ret_code = nrf_drv_spi_transfer( &spi,
                                     spiCmd->txData,
                                     spiCmd->txLength,
                                     spi_rx_buf,
                                     rxLength );

    APP_ERROR_CHECK( ret_code );
    return((ret_code == 0) ? true : false);
}

the values being passed into this function have been confirmed as correct.

Since this issue has a similar symptom of Errata 109, I was wondering if it could be related.

In this case, enabling the Errata 109 workaround is having no effect on the results.

[Nguyen Hoan Hoang]

Have you checked the data sheet of your peripheral to see whether it supports that frequency or not. Some devices work at least 1MHz or more some others at max 1MHz. Make sure you are within range supported by the device.

[Kyle Krueger]

The specification for the device has only maximum speeds listed per command. For the read and write commands we are using, it has 50 MHz listed, so I do not believe this is the problem here.

Since the time of posting I have also seen the problem with 8 MHz. I have updated the question accordingly.