DIS Update Serial Number

[oneguy]

Hi,

I would like to update the Device Information Service's (DIS) serial number characteristic to reflect the actual serial number assigned by our production equipment. I understand that ble_dis.c (as supplied by Nordic) cannot do this.

Now I wonder how this is done best and surely other people wanted to do the same.

What I have done so far:

• Added function ble_dis_update_serial (see below)
• The function actually does something (!) but the serial number string shown in nRF Connect is not correct. To be more specific: it is too long or too short
• I have modified attr_char_value.init_len (to the actual string length) and attr_char_value.max_len (to 16) as suggested in several posts. Unfortunately this does not help. 

Please advise how I can modify DIS "serial number" to accept variable length serial number strings. 

Thank you

Matthias

My function to update the Serial Number characteristic:

void ble_dis_update_serial (uint16_t conn_handle, ble_srv_utf8_str_t serial_num_str)
{
    uint32_t err_code;
    ble_gatts_value_t gatts_value;

    memset (&gatts_value, 0, sizeof (gatts_value));

    gatts_value.len = serial_num_str.length;
    gatts_value.offset = 0;
    gatts_value.p_value = serial_num_str.p_str;

    // Update database.
    err_code = sd_ble_gatts_value_set (conn_handle, serial_num_handles.value_handle, &gatts_value);

}