f_write/f_close cause BLE disconnect

[snowfield]

Hardware: nrf52832

SDK: 16.0.0 with FreeRtos, 

Softdevice: S132 7.0

I set configMAX_PRIORITIES to 5 and modified nrf_sdh_freertos_init to set BLE task priority to 4.

My sd card maintain task priority is set to 2.

For BLE NUS service:

#define MIN_CONN_INTERVAL MSEC_TO_UNITS(20, UNIT_1_25_MS) /**< Minimum acceptable connection interval (20 ms), Connection interval uses 1.25 ms units. */
#define MAX_CONN_INTERVAL MSEC_TO_UNITS(75, UNIT_1_25_MS) /**< Maximum acceptable connection interval (75 ms), Connection interval uses 1.25 ms units. */
#define SLAVE_LATENCY 0 /**< Slave latency. */
#define CONN_SUP_TIMEOUT MSEC_TO_UNITS(4000, UNIT_10_MS) /**< Connection supervisory time-out (4 seconds). */

The NUS service and SD card function works fine when test them separately. But if Operate SD card during NUS connection, I got disconnect with reason:0x8

I have tried to enlarge INTERVAL to 120ms/175ms, also tried to change SLAVE_LATENCY to 4. Problem still exist.

I searched internet and NRF Dev Zone, found some similar question, but none of them can resolve my problem. So I have to raise a new question here. 

 

[snowfield]

Attached SD operation source code below: (This function is called from a task with priority 2.)

static int cmd_get_record_num(unsigned char *buf, int len)
{
    u8 rsp[32];
    s16 imu_file_num;
    s16 env_file_num;
    u32 total_space;
    u32 free_space;
    int rv;
    DIR dir;
    FILINFO fno;

    if(scb.disk_state)
    {
        return RV_CMD_PUB_ERR;
    }

    rsp[0] = CMD_GET_RECORD_NUM;
    rsp[1] = 'V';

    imu_file_num = 0;
    env_file_num = 0;

    rv = f_opendir(&dir,"/");
    if(rv)
    {
        NRF_LOG_INFO("root dir open fail");
        return RV_CMD_PUB_ERR;
    }
    
    do
    {
        rv = f_readdir(&dir, &fno);
        if (rv != FR_OK)
        {
            NRF_LOG_INFO("root read failed.");
            return RV_CMD_PUB_ERR;
        }

        if (fno.fname[0])
        {
            if (fno.fattrib & AM_DIR)
            {
                NRF_LOG_INFO("skip dir:%s",(uint32_t)fno.fname);
                NRF_LOG_FLUSH();
            }
            else
            {
                int dot_pos = 0;
                while(fno.fname[dot_pos] != '.')
                {
                    dot_pos++;
                }
                
                if(memcmp(fno.fname+dot_pos+1,"DAT",3) == 0)
                {
                    if(fno.fname[0] == 'M')
                    {
                        imu_file_num++;
                    }
                    else if(fno.fname[0] == 'E')
                    {
                        env_file_num++;
                    }
                    else
                    {
                        NRF_LOG_INFO("skip dat file:%s",(uint32_t)fno.fname);                        
                        NRF_LOG_FLUSH();
                    }
                }
                else
                {
                    NRF_LOG_INFO("skip file:%s",(uint32_t)fno.fname);                    
                    NRF_LOG_FLUSH();
                }
            }
        }
    }
    while (fno.fname[0]);

    f_closedir(&dir);

    uint32_encode(imu_file_num, rsp+2);
    uint32_encode(env_file_num, rsp+4);

    const nrf_block_dev_geometry_t *p_dev_geom = m_block_dev_sdc.block_dev.p_ops->geometry(&m_block_dev_sdc.block_dev);
    total_space = p_dev_geom->blk_count/2048;
    uint32_encode(total_space, rsp+6);

    free_space = scb.fs.free_clst * scb.fs.csize / 2048;
    uint32_encode(free_space, rsp+10);

    ble_nus_long_send(rsp, 14 );

    NRF_LOG_INFO("list total=%d, free=%d, i_n=%d,e_n=%d",
        total_space,
        free_space,
        imu_file_num,
        env_file_num
        );


    return RV_CMD_ACKED;
}