How to change or define this length?

[Jax]

Hi teams

After I follow this post.

https://devzone.nordicsemi.com/f/nordic-q-a/53909/sending-multiple-packets-at-every-interrupt-interval

And I modify my source code succeed.

The data was separate by 64 bytes?

How to change or define this "64" bytes in SDK15.2?

Please help me. Thank you.

[Amanda Hsieh]

Hi, 

How to change or define this "64" bytes in SDK15.2?

Could you try the following setting in the sdk_config.h?

#define NRF_SDH_BLE_GAP_DATA_LENGTH      68
#define NRF_SDH_BLE_GATT_MAX_MTU_SIZE  64

-Amanda H.

[Jax]

Hi Amanda

Please refer to the picture below.

It looks like not config by this two parameter.

[Amanda Hsieh]

Hi, 

Did you call nrf_ble_gatt_att_mtu_periph_set() in main.c with the value set to 64 like

err_code = nrf_ble_gatt_att_mtu_periph_set(&m_gatt, 64);

somewhere in your code?

-Amanda H.

[Jax]

Hi Amanda

No. I don't use this method.

[Amanda Hsieh]

Hi JaxLiao, 

Jax said:

I don't use this method.

 I think you should have nrf_ble_gatt_att_mtu_periph_set to setting the ATT_MTU size for the next connection that is established as peripheral. 

In e.g. SDK 15.2 in the ble_app_uart example you can set the ATT_MTU with the nrf_ble_gatt_att_mtu_periph_set() function:

/**@brief Function for initializing the GATT library. */
void gatt_init(void)
{
    ret_code_t err_code;

    err_code = nrf_ble_gatt_init(&m_gatt, gatt_evt_handler);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_gatt_att_mtu_periph_set(&m_gatt, NRF_SDH_BLE_GATT_MAX_MTU_SIZE);
    APP_ERROR_CHECK(err_code);
}

-Amanda H.

[Jax]

Hi Amanda

Is this operate equal to directly modify sdk_config.h?

If it's yes. I have already modify sdk_config.h.

But it still separator by 64bytes.

I also added this in my source code.

void conn_evt_len_ext_set(void)
{
    ret_code_t err_code;
    ble_opt_t  opt;

    memset(&opt, 0x00, sizeof(opt));
    opt.common_opt.conn_evt_ext.enable = 1;

    err_code = sd_ble_opt_set(BLE_COMMON_OPT_CONN_EVT_EXT, &opt);
    APP_ERROR_CHECK(err_code);
}

What do you think about this? 

[Amanda Hsieh]

Hi, 

Jax said:

Is this operate equal to directly modify sdk_config.h?

 It set with the NRF_SDH_BLE_GATT_MAX_MTU_SIZE value in the sdk_config.h. 

Could you add nrf_ble_gatt_att_mtu_periph_set() into your main.c?

-Amanda H.

[Jax]

It's a same result.

[Amanda Hsieh]

Hi,

Did you use the nrf_ble_gatt_data_length_set() in the project?

At any time, you can call nrf_ble_gatt_eff_mtu_get or nrf_ble_gatt_data_length_get to retrieve the current parameter value for a given connection.

-Amanda H.