Executing sd_ble_gatts_value_set will result in BLE_ERROR_INVALID_CONN_HANDLE

[sdi_kei]

Hello.

I'm using nrf52832 (S132 v7.0.1, SDK v17.0.0) to develop peripheral roles.

I want to create a characteristic with the Read settings assigned and set the data to it. Therefore, I am using sd_ble_gatts_value_set, but it becomes BLE_ERROR_INVALID_CONN_HANDLE. The following code is the code that causes an error.ble_write_req is called after the characteristic is created.

// UUID Setting
#define ADV_UUID_BASE     {0x77, 0x77, 0x66, 0x66, 0x55, 0x55, 0x44, 0x44, 0x33, 0x33, 0x22, 0x22, 0x11, 0x11, 0x00, 0x00}
#define SERVICE_UUID_BASE {0xHH, 0xHH, 0xGG, 0xGG, 0xFF, 0xFF, 0xEE, 0xEE, 0xDD, 0xDD, 0xCC, 0xCC, 0xBB, 0xBB, 0xAA, 0xAA}

// Characteristic params
static ble_add_char_params_t add_char_params = 
{
    .uuid            = 0xYYYY,
    .uuid_type       = NULL,
    .max_len         = 248,
    .init_len        = 248,
    .is_var_len      = false,
    .char_props.read = 1,
    .read_access     = SEC_OPEN,
};

static uint16_t                 m_service_handle; /**< Handle of local service (as provided by the BLE stack).*/
static ble_gatts_char_handles_t m_char_handles;   /**< Handles of local characteristic (as provided by the BLE stack).*/

// Write Request
static void ble_write_req(void)
{
    ret_code_t        err_code;
    ble_gatts_value_t char_value;
    char *            test_value;

    test_value = "test";

    char_value.len     = sizeof(test_value);
    char_value.offset  = 0;
    char_value.p_value = (uint8_t *)&test_value;

    err_code = sd_ble_gatts_value_set(m_service_handle, m_char_handles.value_handle, &char_value);
    APP_ERROR_CHECK(err_code);
    
    return;
}

I don't know why it's an error. Can you tell me?

Best regards.

[Amanda Hsieh]

Hi, 

BLE_ERROR_INVALID_CONN_HANDLE returned by sd_ble_gatts_value_set means an Invalid connection handle supplied on a system attribute. Check the Connection handle Parameter passed to sd_ble_gatts_value_set. Here is the tutorial that might help https://github.com/NordicPlayground/nRF52-Bluetooth-Course.

Regards,
Amanda 

[sdi_kei]

Hello.

By checking the connection handle again and setting the connection handle when connecting to the BLE device, the error no longer occurs. Thank you very much.

You can now change the characteristic data while connected, but you cannot change it when you are not connected.
Can it be set using sd_ble_gatts_value_set?

Best regards.

[Amanda Hsieh]

Hi, 

sdi_kei said:

Can it be set using sd_ble_gatts_value_set?

Not putty sure what you want to ask. Could you elaborate in more detail?  

sdi_kei said:

By checking the connection handle again and setting the connection handle when connecting to the BLE device, the error no longer occurs. Thank you very much.

You can now change the characteristic data while connected, but you cannot change it when you are not connected.

Seems the issue is fixed and you already have the answer. 

-Amanda

[sdi_kei]

Hello.

Amanda Hsieh said:

Not putty sure what you want to ask. Could you elaborate in more detail? 

What I'd like to ask is how to change the characteristic data before connecting to the BLE device. After connecting, I found that it is possible to use sd_ble_gatts_value_set, but what should I do before connecting?

Best regards.

[Amanda Hsieh]

Hi, 

You could use sd_ble_gatts_value_set with BLE_CONN_HANDLE_INVALID to update the characteristic data. See the use case here and here. 

-Amanda