SPI master transaction SDK V10.0

[sthuang]

Hi everyone,

I used SPI interface to access a external flash with page size 256 bytes.

I found I can't access full page, because the maximum of one SPI transaction is 255 bytes.

I need 260 bytes (include command and data) in one SPI transaction to access full page, is it possible to use SPI transaction more than 255 bytes?

Thank you!

[Jørgen Holmefjord]

Hi,

Unfortunately the SPI driver is limited to a length parameter of size uint8_t. This limit comes from the MAXCNT register size of 8 bit on SPIM peripheral (with EasyDMA support) on nRF52832.

If using legacy SPI peripheral on nRF51822, you should be able to extend the length parameters to 16 bit.

I have attached modified drivers that you can try. Note that there is not guards preventing it from being used with SPIM peripheral, so please use with care.

Fullscreen nrf_drv_spi.c Download

/* Copyright (c) 2015 Nordic Semiconductor. All Rights Reserved.
 *
 * The information contained herein is property of Nordic Semiconductor ASA.
 * Terms and conditions of usage are described in detail in NORDIC
 * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
 *
 * Licensees are granted free, non-transferable use of the information. NO
 * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
 * the file.
 *
 */

#include "nrf_drv_spi.h"
#include "nrf_drv_common.h"
#include "nrf_gpio.h"
#include "nrf_assert.h"
#include "app_util_platform.h"

// This set of macros makes it possible to exclude parts of code when one type
// of supported peripherals is not used.
#if ((SPI0_ENABLED == 1 && SPI0_USE_EASY_DMA == 1 && defined(NRF52)) || \
     (SPI1_ENABLED == 1 && SPI1_USE_EASY_DMA == 1) || \
     (SPI2_ENABLED == 1 && SPI2_USE_EASY_DMA == 1))
    #define SPIM_IN_USE
#endif
#if ((SPI0_ENABLED == 1 && SPI0_USE_EASY_DMA == 0) || \
     (SPI0_ENABLED == 1 && defined(NRF51))         || \
     (SPI1_ENABLED == 1 && SPI1_USE_EASY_DMA == 0) || \
     (SPI2_ENABLED == 1 && SPI2_USE_EASY_DMA == 0))
    #define SPI_IN_USE
#endif
#if (defined(SPIM_IN_USE) && defined(SPI_IN_USE))
    // SPIM and SPI combined
    #define CODE_FOR_SPIM(code) if (p_instance->use_easy_dma) { code }
    #define CODE_FOR_SPI(code)  else { code }
#elif (defined(SPIM_IN_USE) && !defined(SPI_IN_USE))
    // SPIM only
    #define CODE_FOR_SPIM(code) { code }
    #define CODE_FOR_SPI(code)
#elif (!defined(SPIM_IN_USE) && defined(SPI_IN_USE))
    // SPI only
    #define CODE_FOR_SPIM(code)
    #define CODE_FOR_SPI(code)  { code }
#else
    #error "Wrong configuration."
#endif


// Control block - driver instance local data.
typedef struct
{
    nrf_drv_spi_handler_t handler;
    nrf_drv_state_t       state;
    volatile bool         transfer_in_progress;

    // [no need for 'volatile' attribute for the following members, as they
    //  are not concurrently used in IRQ handlers and main line code]
    uint8_t         ss_pin;
    uint8_t         orc;
    uint16_t         tx_buffer_length;
    uint16_t         rx_buffer_length;
    uint16_t         bytes_transferred;
    uint8_t const * p_tx_buffer;
    uint8_t       * p_rx_buffer;

    bool tx_done : 1;
    bool rx_done : 1;
} spi_control_block_t;
static spi_control_block_t m_cb[SPI_COUNT];

static nrf_drv_spi_config_t const m_default_config[SPI_COUNT] = {
#if (SPI0_ENABLED == 1)
    NRF_DRV_SPI_DEFAULT_CONFIG(0),
#endif
#if (SPI1_ENABLED == 1)
    NRF_DRV_SPI_DEFAULT_CONFIG(1),
#endif
#if (SPI2_ENABLED == 1)
    NRF_DRV_SPI_DEFAULT_CONFIG(2),
#endif
};


ret_code_t nrf_drv_spi_init(nrf_drv_spi_t const * const p_instance,
                            nrf_drv_spi_config_t const * p_config,
                            nrf_drv_spi_handler_t handler)
{
    spi_control_block_t * p_cb  = &m_cb[p_instance->drv_inst_idx];

    if (p_cb->state != NRF_DRV_STATE_UNINITIALIZED)
    {
        return NRF_ERROR_INVALID_STATE;
    }

    if (p_config == NULL)
    {
        p_config = &m_default_config[p_instance->drv_inst_idx];
    }

    p_cb->handler = handler;

    uint32_t mosi_pin;
    uint32_t miso_pin;
    // Configure pins used by the peripheral:
    // - SCK - output with initial value corresponding with the SPI mode used:
    //   0 - for modes 0 and 1 (CPOL = 0), 1 - for modes 2 and 3 (CPOL = 1);
    //   according to the reference manual guidelines this pin and its input
    //   buffer must always be connected for the SPI to work.
    if (p_config->mode <= NRF_DRV_SPI_MODE_1)
    {
        nrf_gpio_pin_clear(p_config->sck_pin);
    }
    else
    {
        nrf_gpio_pin_set(p_config->sck_pin);
    }
    NRF_GPIO->PIN_CNF[p_config->sck_pin] =
        (GPIO_PIN_CNF_DIR_Output        << GPIO_PIN_CNF_DIR_Pos)
      | (GPIO_PIN_CNF_INPUT_Connect     << GPIO_PIN_CNF_INPUT_Pos)
      | (GPIO_PIN_CNF_PULL_Disabled     << GPIO_PIN_CNF_PULL_Pos)
      | (GPIO_PIN_CNF_DRIVE_S0S1        << GPIO_PIN_CNF_DRIVE_Pos)
      | (GPIO_PIN_CNF_SENSE_Disabled    << GPIO_PIN_CNF_SENSE_Pos);
    // - MOSI (optional) - output with initial value 0,
    if (p_config->mosi_pin != NRF_DRV_SPI_PIN_NOT_USED)
    {
        mosi_pin = p_config->mosi_pin;
        nrf_gpio_pin_clear(mosi_pin);
        nrf_gpio_cfg_output(mosi_pin);
    }
    else
    {
        mosi_pin = NRF_SPI_PIN_NOT_CONNECTED;
    }
    // - MISO (optional) - input,
    if (p_config->miso_pin != NRF_DRV_SPI_PIN_NOT_USED)
    {
        miso_pin = p_config->miso_pin;
        nrf_gpio_cfg_input(miso_pin, NRF_GPIO_PIN_NOPULL);
    }
    else
    {
        miso_pin = NRF_SPI_PIN_NOT_CONNECTED;
    }
    // - Slave Select (optional) - output with initial value 1 (inactive).
    if (p_config->ss_pin != NRF_DRV_SPI_PIN_NOT_USED)
    {
        nrf_gpio_pin_set(p_config->ss_pin);
        nrf_gpio_cfg_output(p_config->ss_pin);
    }
    m_cb[p_instance->drv_inst_idx].ss_pin = p_config->ss_pin;

    CODE_FOR_SPIM
    (
        NRF_SPIM_Type * p_spim = p_instance->p_registers;
        nrf_spim_pins_set(p_spim, p_config->sck_pin, mosi_pin, miso_pin);
        nrf_spim_frequency_set(p_spim,
            (nrf_spim_frequency_t)p_config->frequency);
        nrf_spim_configure(p_spim,
            (nrf_spim_mode_t)p_config->mode,
            (nrf_spim_bit_order_t)p_config->bit_order);

        nrf_spim_orc_set(p_spim, p_config->orc);

        if (p_cb->handler)
        {
            nrf_spim_int_enable(p_spim,
                NRF_SPIM_INT_ENDTX_MASK | NRF_SPIM_INT_ENDRX_MASK |
                NRF_SPIM_INT_STOPPED_MASK);
        }

        nrf_spim_enable(p_spim);
    )
    CODE_FOR_SPI
    (
        NRF_SPI_Type * p_spi = p_instance->p_registers;
        nrf_spi_pins_set(p_spi, p_config->sck_pin, mosi_pin, miso_pin);
        nrf_spi_frequency_set(p_spi,
            (nrf_spi_frequency_t)p_config->frequency);
        nrf_spi_configure(p_spi,
            (nrf_spi_mode_t)p_config->mode,
            (nrf_spi_bit_order_t)p_config->bit_order);

        m_cb[p_instance->drv_inst_idx].orc = p_config->orc;

        if (p_cb->handler)
        {
            nrf_spi_int_enable(p_spi, NRF_SPI_INT_READY_MASK);
        }

        nrf_spi_enable(p_spi);
    )

    if (p_cb->handler)
    {
        nrf_drv_common_irq_enable(p_instance->irq, p_config->irq_priority);
    }

    p_cb->transfer_in_progress = false;
    p_cb->state = NRF_DRV_STATE_INITIALIZED;

    return NRF_SUCCESS;
}

void nrf_drv_spi_uninit(nrf_drv_spi_t const * const p_instance)
{
    spi_control_block_t * p_cb = &m_cb[p_instance->drv_inst_idx];
    ASSERT(p_cb->state != NRF_DRV_STATE_UNINITIALIZED);

    if (p_cb->handler)
    {
        nrf_drv_common_irq_disable(p_instance->irq);
    }

    #define DISABLE_ALL  0xFFFFFFFF
    CODE_FOR_SPIM
    (
        NRF_SPIM_Type * p_spim = p_instance->p_registers;
        if (p_cb->handler)
        {
            nrf_spim_int_disable(p_spim, DISABLE_ALL);
        }
        nrf_spim_disable(p_spim);
    )
    CODE_FOR_SPI
    (
        NRF_SPI_Type * p_spi = p_instance->p_registers;
        if (p_cb->handler)
        {
            nrf_spi_int_disable(p_spi, DISABLE_ALL);
        }
        nrf_spi_disable(p_spi);
    )
    #undef DISABLE_ALL

    p_cb->state = NRF_DRV_STATE_UNINITIALIZED;
}

#ifdef SPI_IN_USE
// This function is called from IRQ handler or, in blocking mode, directly
// from the 'nrf_drv_spi_transfer' function.
// It returns true as long as the transfer should be continued, otherwise (when
// there is nothing more to send/receive) it returns false.
static bool transfer_byte(NRF_SPI_Type * p_spi, spi_control_block_t * p_cb)
{
    // Read the data byte received in this transfer and store it in RX buffer,
    // if needed.
    volatile uint8_t rx_data = nrf_spi_rxd_get(p_spi);
    if (p_cb->bytes_transferred < p_cb->rx_buffer_length)
    {
        p_cb->p_rx_buffer[p_cb->bytes_transferred] = rx_data;
    }

    ++p_cb->bytes_transferred;

    // Check if there are more bytes to send or receive and write proper data
    // byte (next one from TX buffer or over-run character) to the TXD register
    // when needed.
    // NOTE - we've already used 'p_cb->bytes_transferred + 1' bytes from our
    //        buffers, because we take advantage of double buffering of TXD
    //        register (so in effect one byte is still being transmitted now);
    //        see how the transfer is started in the 'nrf_drv_spi_transfer'
    //        function.
    uint16_t bytes_used = p_cb->bytes_transferred + 1;
    if (bytes_used < p_cb->tx_buffer_length)
    {
        nrf_spi_txd_set(p_spi, p_cb->p_tx_buffer[bytes_used]);
        return true;
    }
    else if (bytes_used < p_cb->rx_buffer_length)
    {
        nrf_spi_txd_set(p_spi, p_cb->orc);
        return true;
    }

    return (p_cb->bytes_transferred < p_cb->tx_buffer_length ||
            p_cb->bytes_transferred < p_cb->rx_buffer_length);
}
#endif // SPI_IN_USE

ret_code_t nrf_drv_spi_transfer(nrf_drv_spi_t const * const p_instance,
                                uint8_t const * p_tx_buffer,
                                uint16_t         tx_buffer_length,
                                uint8_t       * p_rx_buffer,
                                uint16_t         rx_buffer_length)
{
    spi_control_block_t * p_cb  = &m_cb[p_instance->drv_inst_idx];
    ASSERT(p_cb->state != NRF_DRV_STATE_UNINITIALIZED);
    ASSERT(p_tx_buffer != NULL || tx_buffer_length == 0);
    ASSERT(p_rx_buffer != NULL || rx_buffer_length == 0);

    if (p_cb->transfer_in_progress)
    {
        return NRF_ERROR_BUSY;
    }

    // Finish zero-length transfers immediately.
    if (tx_buffer_length == 0 && rx_buffer_length == 0)
    {
        return NRF_SUCCESS;
    }

    // Activate Slave Select signal, if it is to be used.
    if (p_cb->ss_pin != NRF_DRV_SPI_PIN_NOT_USED)
    {
        nrf_gpio_pin_clear(p_cb->ss_pin);
    }

    CODE_FOR_SPIM
    (
        // EasyDMA requires that transfer buffers are placed in Data RAM region;
        // signal error if they are not.
        if ((p_tx_buffer != NULL && !nrf_drv_is_in_RAM(p_tx_buffer)) ||
            (p_rx_buffer != NULL && !nrf_drv_is_in_RAM(p_rx_buffer)))
        {
            return NRF_ERROR_INVALID_ADDR;
        }

        NRF_SPIM_Type * p_spim = p_instance->p_registers;

        nrf_spim_tx_buffer_set(p_spim, p_tx_buffer, tx_buffer_length);
        nrf_spim_rx_buffer_set(p_spim, p_rx_buffer, rx_buffer_length);

        nrf_spim_event_clear(p_spim, NRF_SPIM_EVENT_ENDTX);
        nrf_spim_event_clear(p_spim, NRF_SPIM_EVENT_ENDRX);
        p_cb->tx_done = false;
        p_cb->rx_done = false;
        
        if (p_cb->handler)
        {
            p_cb->transfer_in_progress = true;
        }
        
        nrf_spim_event_clear(p_spim, NRF_SPIM_EVENT_STOPPED);
        nrf_spim_task_trigger(p_spim, NRF_SPIM_TASK_START);

        if (!p_cb->handler)
        {
            while (!nrf_spim_event_check(p_spim, NRF_SPIM_EVENT_ENDTX) ||
                   !nrf_spim_event_check(p_spim, NRF_SPIM_EVENT_ENDRX)) {}

            // Stop the peripheral after transaction is finished.
            nrf_spim_task_trigger(p_spim, NRF_SPIM_TASK_STOP);
            while (!nrf_spim_event_check(p_spim, NRF_SPIM_EVENT_STOPPED)) {}
            if (p_cb->ss_pin != NRF_DRV_SPI_PIN_NOT_USED)
            {
                nrf_gpio_pin_set(p_cb->ss_pin);
            }
        }
    )
    CODE_FOR_SPI
    (
        NRF_SPI_Type * p_spi = p_instance->p_registers;

        p_cb->p_tx_buffer       = p_tx_buffer;
        p_cb->tx_buffer_length  = tx_buffer_length;
        p_cb->p_rx_buffer       = p_rx_buffer;
        p_cb->rx_buffer_length  = rx_buffer_length;
        p_cb->bytes_transferred = 0;

        

        if (p_cb->handler)
        {
            p_cb->transfer_in_progress = true;
            nrf_spi_int_disable(p_spi, NRF_SPI_INT_READY_MASK);
        }
        nrf_spi_event_clear(p_spi, NRF_SPI_EVENT_READY);
        
        // Start the transfer by writing some byte to the TXD register;
        // if TX buffer is not empty, take the first byte from this buffer,
        // otherwise - use over-run character.
        nrf_spi_txd_set(p_spi,
            (tx_buffer_length > 0 ?  p_tx_buffer[0] : p_cb->orc));
        
        // TXD register is double buffered, so next byte to be transmitted can
        // be written immediately, if needed, i.e. if TX or RX transfer is to
        // be more that 1 byte long. Again - if there is something more in TX
        // buffer send it, otherwise use over-run character.
        if (tx_buffer_length > 1)
        {
            nrf_spi_txd_set(p_spi, p_tx_buffer[1]);
        }
        else if (rx_buffer_length > 1)
        {
            nrf_spi_txd_set(p_spi, p_cb->orc);
        }

        // For blocking mode (user handler not provided) wait here for READY
        // events (indicating that the byte from TXD register was transmitted
        // and a new incoming byte was moved to the RXD register) and continue
        // transaction until all requested bytes are transferred.
        // In non-blocking mode - IRQ service routine will do this stuff.
        if (p_cb->handler)
        {
            nrf_spi_int_enable(p_spi, NRF_SPI_INT_READY_MASK);
        }
        else
        {
            do {
                while (!nrf_spi_event_check(p_spi, NRF_SPI_EVENT_READY)) {}
                nrf_spi_event_clear(p_spi, NRF_SPI_EVENT_READY);
            } while (transfer_byte(p_spi, p_cb));
            if (p_cb->ss_pin != NRF_DRV_SPI_PIN_NOT_USED)
            {
                nrf_gpio_pin_set(p_cb->ss_pin);
            }
        }
    )

    return NRF_SUCCESS;
}

static void finish_transfer(spi_control_block_t * p_cb)
{
    // If Slave Select signal is used, this is the time to deactivate it.
    if (p_cb->ss_pin != NRF_DRV_SPI_PIN_NOT_USED)
    {
        nrf_gpio_pin_set(p_cb->ss_pin);
    }

    // By clearing this flag before calling the handler we allow subsequent
    // transfers to be started directly from the handler function.
    p_cb->transfer_in_progress = false;
    p_cb->handler(NRF_DRV_SPI_EVENT_DONE);
}

#ifdef SPIM_IN_USE
static void irq_handler_spim(NRF_SPIM_Type * p_spim, spi_control_block_t * p_cb)
{
    ASSERT(p_cb->handler);

    if (nrf_spim_event_check(p_spim, NRF_SPIM_EVENT_STOPPED))
    {
        nrf_spim_event_clear(p_spim, NRF_SPIM_EVENT_STOPPED);
        finish_transfer(p_cb);
    }
    else
    {
        if (nrf_spim_event_check(p_spim, NRF_SPIM_EVENT_ENDTX))
        {
            nrf_spim_event_clear(p_spim, NRF_SPIM_EVENT_ENDTX);
            p_cb->tx_done = true;
        }
        if (nrf_spim_event_check(p_spim, NRF_SPIM_EVENT_ENDRX))
        {
            nrf_spim_event_clear(p_spim, NRF_SPIM_EVENT_ENDRX);
            p_cb->rx_done = true;
        }

        if (p_cb->tx_done && p_cb->rx_done)
        {
            nrf_spim_task_trigger(p_spim, NRF_SPIM_TASK_STOP);
        }
    }
}
#endif // SPIM_IN_USE

#ifdef SPI_IN_USE
static void irq_handler_spi(NRF_SPI_Type * p_spi, spi_control_block_t * p_cb)
{
    ASSERT(p_cb->handler);

    nrf_spi_event_clear(p_spi, NRF_SPI_EVENT_READY);

    if (!transfer_byte(p_spi, p_cb))
    {
        finish_transfer(p_cb);
    }
}
#endif // SPI_IN_USE

#if (SPI0_ENABLED == 1)
void SPI0_IRQ_HANDLER(void)
{
    #if (SPI0_USE_EASY_DMA == 1) && defined(NRF52)
        irq_handler_spim(NRF_SPIM0,
    #else
        irq_handler_spi(NRF_SPI0,
    #endif
            &m_cb[SPI0_INSTANCE_INDEX]);
}
#endif // (SPI0_ENABLED == 1)

#if (SPI1_ENABLED == 1)
void SPI1_IRQ_HANDLER(void)
{
    #if (SPI1_USE_EASY_DMA == 1)
        irq_handler_spim(NRF_SPIM1,
    #else
        irq_handler_spi(NRF_SPI1,
    #endif
            &m_cb[SPI1_INSTANCE_INDEX]);
}
#endif // (SPI1_ENABLED == 1)

#if (SPI2_ENABLED == 1)
void SPI2_IRQ_HANDLER(void)
{
    #if (SPI2_USE_EASY_DMA == 1)
        irq_handler_spim(NRF_SPIM2,
    #else
        irq_handler_spi(NRF_SPI2,
    #endif
            &m_cb[SPI2_INSTANCE_INDEX]);
}
#endif // (SPI2_ENABLED == 1)

nrf_drv_spi.h

Best regards,
Jørgen