I am trying to create a L2CAP CoC between a nRF52840 SoC using nRF5 SDK version 15.3.0 and a Pixel 3 XL running Android 12 without the use of GATT. Currently I use GAP for the discovery and connection setup, after which I try and create a L2CAP CoC. On Android my (pseudo)code looks like this:scanner.startScan()
if (device.name == "L2CAP_COC_DEMO") {
socket = device.createInsecureL2capChannel(psm)
socket.connect()
}
As I completely control both sides of this connection I chose to hardcode the PSM on both sides. This causes the nRF52840 so produce the following flow:
<info> app: STARTING ADVERTISING<info> app: BLE EVT: BLE_GAP_EVT_CONNECTED, EVT CODE: 16<info> app: Connected<info> app: BLE EVT: BLE_GAP_EVT_DATA_LENGTH_UPDATE_REQUEST, EVT CODE: 35<info> app: BLE EVT: BLE_GAP_EVT_DATA_LENGTH_UPDATE, EVT CODE: 36<info> app: BLE EVT: BLE_GAP_EVT_PHY_UPDATE_REQUEST, EVT CODE: 33<info> app: BLE EVT: BLE_GAP_EVT_PHY_UPDATE, EVT CODE: 34<info> app: BLE EVT: BLE_L2CAP_EVT_CH_SETUP_REQUEST, EVT CODE: 112<info> app: BLE EVT: BLE_L2CAP_EVT_CH_SDU_BUF_RELEASED, EVT CODE: 116<info> app: BLE EVT: BLE_L2CAP_EVT_CH_SETUP_REFUSED, EVT CODE: 113<error> app: BLE_L2CAP_CH_SETUP_REFUSED_SRC_REMOTE<error> app: BLE_L2CAP_CH_STATUS_CODE_LE_PSM_NOT_SUPPORTED
As a result I started looking in the Nordic documentation for how to respond to the BLE_L2CAP_EVT_CH_SETUP_REQUEST event, this is what I found:
- Reply to a setup request of an L2CAP channel (if called in response to a BLE_L2CAP_EVT_CH_SETUP_REQUEST event): sends an LE Credit Based Connection Response packet to a peer.
This is talking about the sd_ble_l2cap_ch_setup() method. However when looking at the variables the method needs to function, it shows this:
| [in] | conn_handle | Connection Handle. |
| [in,out] | p_local_cid | Pointer to a uint16_t containing Local Channel ID of the L2CAP channel:
|
| [in] | p_params | L2CAP channel parameters. |
For p_local_cid it clearly states as input it is possible to get a local_cid which is provided in BLE_L2CAP_EVT_CH_SETUP_REQUEST event when replying. However, when looking at ble_l2cap_evt_ch_setup_request_t which is the struct supplied by the event, it supplies no local_cid. Below is a copy from the documentation (and no, the ble_l2cap_ch_tx_params_t struct also does not contain a local_cid field).
Data Fields |
|
| ble_l2cap_ch_tx_params_t | tx_params |
| uint16_t | le_psm |
Here are some links to the relevant documentation to save you some surfing time:
https://docs.nordicsemi.com/bundle/s140_v6.1.1_api/page/structble_l2cap_evt_ch_setup_request_t.html
So my question is how to correctly respond to the BLE_L2CAP_EVT_CH_SETUP_REQUEST event. Additionally, it seems the documentation is either incomplete or incorrect. Any responses are appreciated, thanks in advance!
