cannot update notification value

RE: cannot update notification value

Hung Bui — Thu, 20 Jul 2017 07:43:02 GMT

This "No. I want to call sd_ble_gatts_hvx() regardless ble connection handle." doesn't make sense.

Can you explain why you want to do that ?

RE: cannot update notification value

endnode — Wed, 19 Jul 2017 13:10:46 GMT

No I cannot explain it, I can only say that if connection handle is invalid then sd_ble_gatts_hvx() should return BLE_ERROR_INVALID_CONN_HANDLE. If you receive NRF_SUCCESS then it is a bug BUT I would be very careful and check your code not twice but triple time because I assume Nordic is testing this in their Soft Device release cycle quite well.

RE: cannot update notification value

endnode — Wed, 19 Jul 2017 13:06:57 GMT

If connection handle is invalid then it means there is no connection so there is no GATT Client connected and so it cannot receive any notification. Your case doesn't make sense.

RE: cannot update notification value

Haruki Kawakami — Wed, 19 Jul 2017 13:06:33 GMT

I know that. So this phenomenon is strange. document doesn't describe this phenomenon. just explains it returns BLE_ERROR_INVALID_CONN_HANDLE. Would you explain me why this phenomenon occurs if this is not bug.

RE: cannot update notification value

endnode — Wed, 19 Jul 2017 12:52:36 GMT

If connection handle is invalid then calling this function doesn't make any sense.

RE: cannot update notification value

Haruki Kawakami — Wed, 19 Jul 2017 12:46:45 GMT

Even if ble connection is valid and client enable CCCD, I can't transport data other than first string I provide to the function once I call sd_ble_gatts_hvx() while ble connection handle is invalid.

RE: cannot update notification value

Haruki Kawakami — Wed, 19 Jul 2017 12:39:25 GMT

No. I want to call sd_ble_gatts_hvx() regardless ble connection handle.

RE: cannot update notification value

Hung Bui — Wed, 19 Jul 2017 11:38:26 GMT

You mean updating the value but not sending notification ? If you want to update the value of the characteristic locally, please call sd_ble_gatts_value_set() instead.

RE: cannot update notification value

endnode — Wed, 19 Jul 2017 09:04:29 GMT

Not really, sd_ble_gatts_hvx() returning NRF_SUCCESSonly means that packet got stored into one of Tx buffers inside Soft Device. Once it goes really out you will get specific event (in the latest SDK it's called BLE_GATTS_EVT_HVN_TX_COMPLETE) and only then another Handle Value Notification packet gets out. Note that there isn't only one Tx buffer in the SD so you can "stack" at least 6 packets in advance. Apart from this all works without problems, no bug known that SD would not transport data out or that you wouldn't be able to transport other data then first string you provide to the function. Are you sure it's not bug in your code before calling sd_ble_gatts_hvx() function?