Smart Remote 3, keyboard keys are not received on Android TV when disabling power management

[sguitton01]

Hi all, 

I get a really weird issue developing on the smart remote 3 project.

I work with my own hardware design, and as I want a specific behaviour I disabled power_management go to sys off when remote is disconnecting or when the advertising stops.

Once I have done this, when testing on Android TV (Nvidia Shied alike), I can connect correctly to it, I get voice and consumer keys but Keyboard keys are not always received (sometimes I get all of them (20% of times), or none (80%)). It seems that sometimes I connect alright and sometimes I don't. It works perfectly on Windows and on smartphones.

Can you reproduce this issue? Do you have any idea how to solve this issue?

Thanks in advance

[Edvin]

Hello,

(sometimes I get all of them (20% of times), or none (80%)

 

 Ok, so that would suggest that there is not something wrong in the way that you set up the characteristic for the HID keyboard. 

I didn't quite understand the shutdown things you explained. You disable all shutdown, so that nrf_pwr_mgmt_shutdown() is never called? Is that correct?

Can you check one thing? When you press a button (keyboard key), and it doesn't go through, can you find the sd_ble_gatts_hvx() that is called when you press the key? What does it return?

Best regards,

Edvin

[sguitton01]

Hello Edvin,

Yes I mentionned that I disabled all  nrf_pwr_mgmt_shutdown() and it seems that it's at that point the issue appeared.

When I have the issue and pressing a button (keyboard), sd_ble_gatts_hvx() still returns NRF_SUCCESS.

Best regards,

Sylvain

[Audun]

Hi Sylvain,

after removing the nrf_pwr_mgmt_shutdown() calls, have you added additional logic to for example start automatically advertising when a button is pressed and there is no connection?

When the problem occurs, have there been any cycles of disconnect+connect before the connection is established again? I wonder if it's possible that the host has some lingering state information causing trouble.

You can look at the M_COMS_BLE_EVT_CONN_UPDATE and M_COMS_BLE_EVT_CONN_SECURED log printouts and the timestamp of these logs (relative to M_COMS_BLE_EVT_CONNECTED event printout) to see if the host behavior is consistent between the working and non-working cases. For example, normally the Host will enable encryption immediately after connecting to a paired remote, but the remote will request encryption if the Host hasn't enabled it within CONFIG_ENC_REQ_DELAY ms after reconnection (ref. m_coms_ble.c::s_encryption_timer)

Also, have you looked at the log output from the Android side? (https://developer.android.com/studio/command-line/logcat) Perhaps comparing the logcat output from a working and failing case could yield some clues.

Best regards,

Audun

[sguitton01]

Hi Edvin, Audun,

I did a lot more experimentation I know have a better diagnostic of the issue.

It's the nrf_pwr_mgmt_shutdown() from disconnected event that when he is withdrawn causes the issue.

I did add  some code to start advertising if not connected when pressing a key?

I do have multiple M_COMS_BLE_EVT_CONN_UPDATE on android TV which I do not have on other devices.

Here's what I can see :

- On first pairing with the box, everything works fine, I have all the keys and everything. If I disconnect by going out of range for example or by rebooting the remote, I still have everything OK.

- The issue appears when I reboot the box. Then I reconnect alright but I do not get the keyboard keys

- If I have everything ok, and I reboot the box AND the remote at the same time. When I reconnect everything is alright. This is why when I keep the nrf_pwr_mgmt_shutdown() it works.

- Once I have the issue rebooting the remote does not solve it. I must reboot, unpair and re-pair to the box

- Something odd is that if I have the issue and I unpair the remote, connect to another device (windows or android phone) I still have the issue on these devices. I must reboot then unpair to make it work.

I hope these information will be helpfull.

Best regards,

Sylvain

[Audun]

Thanks for the additional information, Sylvain. What version Android TV are you testing with? We can  try to reproduce the issue here by removing nrf_pwr_mgmt_shutdown() from default code.

[sguitton01]

I'm on Android TV 7.1.2 with security patch from 1 december 2017 but I also get issues on android 8.0.0 with security patch from 5 december 2018 

[Audun]

Can you share some more details regarding the function you call to advertise when disconnected and a button is pressed?
I've done some testing on a Nexus Player running Android 8.0, but haven't seen the issue yet.

I made the following modifications to default SR3 v1.2.1 (PCA63519 hardware) to recreate your setup:

- In application sdk_config.h, set NRF_PWR_MGMT_CONFIG_STANDBY_TIMEOUT_ENABLED 0

- Remove all calls to nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_SYSOFF)

- Added the following behavior when a button is pressed and remote is not currently connected:

if (!m_coms_ble_adv_running())
{
    (void) m_coms_ble_advertise(false);
}

I also tried with m_coms_ble_advertise(true), but this will cause the remote to erase the existing bond if CONFIG_MAX_BONDS ==1 (default value), in order to free up enough space in bond database to create new bond. In this case I ended up in an connect/disconnect cycle with the Nexus Player due to encryption failing (encryption keys erased by remote).

Please let me know if I'm missing some important difference between our setups