HID Keyboard example Error NRF_INVALID_STATE

[Koldo]

Hi,

I am working with the HID keyboard example in the pca10028 development kit and I facing following problem.

I can connect, pair and bod with Android and IOS devices and send receive the "hello" message sent by the program when pushing the button in the board.

The problem comes when I disconnect. In both IOS and Android it connects inmediately as they are bonded, but in Android I receive error 0x8 (NRF_INVALID_STATE) after the sd_ble_gatts_hvx(). I suppose this is because the notifications/indications are not enabled in Android device for CCCD.

The issue is that it works perfectly in IOS, so it seems that this is an Android issues. I checked different smartphones and no one works after reconnection.

I am pairing using the smartphone Bluetooth menu and I don't want to develope any other app for the smartphone, just connect my device and use it like keyboard.

Is there any solution for this? Can something be done in the firmware to enable notiications in the peer?

Thank you

Regards

[Koldo]

I am going to answer to myself.

The issue was solved by incrementing the DM_GATT_CCD_COUNT.

I don't know exactly why this solved the issue.

[Kenneth]

Hi, the DM_GATT_CCCD_COUNT should be set to minimum the number of characteristics you have that support notifications or indications. Also take into account that you may have a service changed notification enabled in the softdevice.

[Koldo]

Hi Kenneth,

I just program the HID Keyboard example and whille for IOS it was not needed to update the DM_GATT_CCCD_COUNT because it reconnected perfectly for Android it was neccesary. Does Android use more characterisitic notifications than IOS?

Thank you in advance.

[Kenneth]

Not likely, it may however be that iOS re-enable them somehow, but in any case DM_GATT_CCCD_COUNT should be increased in this case.

[Koldo]

Thank you Kenneth. I will do.