Connection parameter update issue

RE: Connection parameter update issue

Sigurd — Fri, 22 Sep 2023 09:29:51 GMT

You are using the connection param update module in your code.

If you have this code below in your main.c, then try removing that.

    case BLE_GAP_EVT_CONN_PARAM_UPDATE:
    {
      // Accepting parameters requested
      err_code = sd_ble_gap_conn_param_update(p_gap_evt->conn_handle, &p_gap_evt->params.conn_param_update.conn_params);
      APP_ERROR_CHECK(err_code);
    } break;

Also,
you will get notified about if the negotiation was a success, or if the negotiation procedure failed in on_conn_params_evt() handler.

RE: Connection parameter update issue

rsf — Thu, 21 Sep 2023 13:06:25 GMT

yes i get that

No.     Time           Source                Destination           Protocol Length Info
237     9.618916       Master_0x506573e6     Slave_0x506573e6      LE LL    38     Control Opcode: LL_CONNECTION_UPDATE_IND

Frame 237: 38 bytes on wire (304 bits), 38 bytes captured (304 bits) on interface COM6-4.0, id 0
nRF Sniffer for Bluetooth LE
Bluetooth Low Energy Link Layer
    Access Address: 0x506573e6
    [Master Address: 55:11:5c:c4:15:5e (55:11:5c:c4:15:5e)]
    [Slave Address: fe:95:21:38:7b:d5 (fe:95:21:38:7b:d5)]
    Data Header
        .... ..11 = LLID: Control PDU (0x3)
        .... .0.. = Next Expected Sequence Number: 0 [ACK]
        .... 0... = Sequence Number: 0 [OK]
        ...1 .... = More Data: True
        ..0. .... = CTE Info: Not Present
        00.. .... = RFU: 0
        Length: 12
    Control Opcode: LL_CONNECTION_UPDATE_IND (0x00)
    Window Size: 3 (3.75 msec)
    Window Offset: 0 (0 msec)
    Interval: 24 (30 msec)
    Latency: 0
    Timeout: 200 (2000 msec)
    Instant: 93
    [Connection Parameters in: 58]
    CRC: 0x041631

i thought that this message indicates that we want to start with 7.5ms but the iphone wants 30ms. and i thought we update our parameters to 30ms in the update event

    case BLE_GAP_EVT_CONN_PARAM_UPDATE:
    {
      // Accepting parameters requested
      err_code = sd_ble_gap_conn_param_update(p_gap_evt->conn_handle, &p_gap_evt->params.conn_param_update.conn_params);
      APP_ERROR_CHECK(err_code);
    } break;

RE: Connection parameter update issue

Sigurd — Thu, 21 Sep 2023 12:10:19 GMT

Hi!

[quote user=""]the iphone always rejects the update[/quote]

You wont' get 7.5ms connection interval with a iPhone.

https://developer.apple.com/accessories/Accessory-Design-Guidelines.pdf
page 193

RE: Connection parameter update issue

rsf — Thu, 21 Sep 2023 07:35:31 GMT

Hello

//initialize connection parameters module.
static uint32_t conn_params_init(void)
{
  ret_code_t             err_code;
  ble_conn_params_init_t cp_init;

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

  cp_init.p_conn_params                  = NULL;
  cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;
  cp_init.next_conn_params_update_delay  = NEXT_CONN_PARAMS_UPDATE_DELAY;
  cp_init.max_conn_params_update_count   = MAX_CONN_PARAMS_UPDATE_COUNT;
  cp_init.start_on_notify_cccd_handle    = BLE_GATT_HANDLE_INVALID;
  cp_init.disconnect_on_fail             = false;
  cp_init.evt_handler                    = on_conn_params_evt;
  cp_init.error_handler                  = conn_params_error_handler;

  err_code = ble_conn_params_init(&cp_init);
  return err_code;
}

that's the conn_params_init() function. but this one shouldn't cause the issue i think, because we are handling the error and the device should enter an error stat if the return value is not "success".

i think the update of the connection parameters is the issue

case BLE_GAP_EVT_CONN_PARAM_UPDATE:
    {
      // Accepting parameters requested
      err_code = sd_ble_gap_conn_param_update(p_gap_evt->conn_handle, &p_gap_evt->params.conn_param_update.conn_params);
      APP_ERROR_CHECK(err_code);
    } break;

if i remove this line from the code we dont react to connection parameter updates and the connection breaks after 3 attempts (#define MAX_CONN_PARAMS_UPDATE_COUNT 3).
if i leave this line in the code. the connection parameter update request appears every couple of milliseconds but gets rejected.

RE: Connection parameter update issue

mrono — Thu, 21 Sep 2023 07:13:51 GMT

How do you initialize the conn_params module? There is a member in the ble_conn_params_init_t -struct called disconnect_on_fail, which determines if you want to disconnect in case you don't get the parameters you want.

The same struct also has pointers to event handlers for connection events. I think the example event handler from Nordic also disconnects if parameters end up outside the limits you specify. So if you based your code on an example check that too.

Or is it the iphone that disconnects if you keep asking too many times? If so the I guess lowering that count is the best option.