Can't read characteristics of BLE HID service example

[Sven]

I'm trying to implement the HID service on a custom nrf52832 board, unfortunately I'm running into problems.

Here's what happens: Advertising, connecting to the board, service discovery, GPIOs (buttons & LEDs), reading the battery level, etc. all work great. I use nRF Connect to test this. However when trying to read HID characteristics (except for the protocol mode), the operation never finishes (the spinner keeps spinning). The log does not show any errors or other entries, except for the battery service updates that keep coming in. When I hit disconnect the spinner stops and the device is discoverable again.

The same happens when I use the "enable all services" menu item like described in the example. The HID device also doesn't produce any input in Android, even when connecting through settings and enabling "use for input device").

At first I suspected problems in my code, but now I'm running the unmodified examples (with -DBOARD_CUSTOM though) and have the exact same issue. I tried both the HID mouse and keyboard example. I'm using version 12.2 of the nRF5 SDK, though I'm getting the same result with 12.0.

Any ideas what's going wrong? I'd also appreciate any hints on how to further debug this.

[Sven]

Regarding the scheduler, yes that's exactly why I'm asking. As I wrote the example doesn't work for me, so it's a bit hard to check. (But it's more of a side question for me, I don't really care about it.)

[Sven]

Okay, I haven't made myself clear enough. Your hex not working on my hardware does point to a hardware problem, but I really don't see how that would happen. I'm using a OnePlus 3T with Android 7.0. Service discovery works fine, nRF Connect lists all the services on my device (battery service, device information service, a custom service, etc.) and can read all characteristics, except for the HID service. I.e. I click the read symbol of a HID characteristic and never get a result.

[FormerMember]

I have updated my answer.

[Sven]

Hey Kristin, sorry for the long delay. I was eventually able to get the HID service running. Nice catch with those "protected services". Android could've definitely made that more clear. For some reason I didn't get the disconnect in the log, quite the opposite, the battery level notifications kept coming in. Looks like the BLE stack on my phone is a little flaky, it doesn't like changing HID descriptors at all (e.g. when switching from a keyboard to a mouse or gamepad). That's why I couldn't get your hex file to work, simply reconnecting or unbonding isn't enough, I have to reboot the phone for it to work... The step by step guide in the examples should probably be updated with a remark about those limitations on Android. That's what confused me in the first place.

[Sven]

Anyway, thank you again for your help.