What can cause BLE_HIDS_EVT_NOTIF_ENABLED not to be sent by Host(Xiaomi TV).

[Jacey]

I have a simple HID BLE device which send left/right/return/home keys to a Android device.it works well when i test it on my android phone(Lenovo S5).but when i test it on my Xiaomi TV :it works well when if it is first time to pair with the TV, but if I turn off and then turn on the TV again,it can be connected successfully，but  the keys no longer working.i find the difference in the log：when BLE_HIDS_EVT_NOTIF_ENABLED event not to be sent，it fails.

<info> app: Fast advertising.

<info> app: Connected
<info> peer_manager_handler: Connection secured: role: Peripheral, conn_handle: 0, procedure: Bonding
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Bonding data, action: Update
<info> app: New Bond, add the peer to the whitelist if possible
<info> app: m_whitelist_peer_cnt 2, MAX_PEERS_WLIST 8
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Peer rank, action: Update
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Local database, action: Update
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Central address resolution, action: Update
<info> app: BLE_HIDS_EVT_NOTIF_ENABLED
<info> app: BLE_HIDS_EVT_NOTIF_ENABLED

<info> app: on_disconnected
<info> app: High Duty Directed advertising.
<info> app: Disconnected
<info> app: Fast advertising with whitelist.
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Peer rank, action: Update, no change
<info> app: Connected
<info> peer_manager_handler: Connection secured: role: Peripheral, conn_handle: 0, procedure: Encryption
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Peer rank, action: Update, no change

SDK version is nRF5 Software Development Kit v16.0.0、s132_nrf52_7.0.1_softdevice，the demo i am learning is ble_app_hids_keyboard.

[Jacey]

https://devzone.nordicsemi.com/f/nordic-q-a/35088/keyboard-example-failure-in-sending-keys-after-power-cycle-with-android-kitkat I find this topic said about the incompatibility of different android version，my android phone'version is 8.0.0,my TV's version is 6.0.1.Is it really caused by incompatibility with different android version?

[Jacey]

I debuged the program to find it returns NRF_ERROR_INVALID_STATE(0x08) when calling sd_ble_gatts_hvx api in ble_hids_inp_rep_send function.How to find the problom?Maybe there are differences between (pair & bond) and the reconndection?

[Simonr]

Hi

Please take a look at this case which handles the same error as the one you're seeing, complete with a solution from the reporter.

Best regards,

Simon

[Jacey]

Hi,Simon!

I know that erasing bonds and do pair & bond again it works,but what i want to achieve is a remote control.I just want to pair & bond at the first time and then it can reconnect automatically and send keys well.

TKS!

[Simonr]

Hi

The INVALID_STATE error is returned for one of the following reasons:

• Invalid Connection State
• Notifications and/or indications not enabled in the CCCD
• An ATT_MTU exchange is ongoing

Can you check if the connection handle used by the HID peripheral connection is assigned to the m_conn_handle variable you're passing to ble_hids_inp_rep_send()? If it isn't that would be why you get the invalid state error.

Best regards,

Simon