RE: I can't write 1 to a protected CCCD

Andrew Ong — Fri, 28 Sep 2018 22:40:11 GMT

Thanks Aryan. That helped. I also found out that for my protected characteristic, given the following header:

static void on_rw_authorize_req(health_data_service_t * p_service, ble_evt_t const * p_ble_evt)
{
ble_gatts_evt_rw_authorize_request_t const * req = &p_ble_evt->evt.gatts_evt.params.authorize_request;

I had to read from

req->request.write.handle == p_service->rx_handles.cccd_handle

not

p_evt_write->handle == p_service->rx_handles.cccd_handle

Nevermind the question about the unprotected characteristic. I was looking at the wrong characteristic number.

RE: I can't write 1 to a protected CCCD

Susheel Nuguru — Thu, 27 Sep 2018 08:00:18 GMT

Hi Andrew,

There are two types of writes you can do here

1) The first one is "Write with Authorization" where you will get BLE_GATTS_EVT_WRITE event and the application needs to review the request and write to the characteristic manually using sd_ble_gatts_value_set. You can see the message sequence chart for this here

2) The second one is the "Write Request with Authorization" , where the application will get BLE_GATTS_EVT_RW_AUTHORIZE_REQUEST like you mentioned in your question and you set the characteristic to the requested value (or some other value) and give the response to the peer as a write response. The MSC for this can be seen here.

Since your BLE handler is getting BLE_GATTS_EVT_WRITE event, this clearly means that the peer is doing a Write command instead of using the Write Request.

Write Command from peer (client)-> BLE_GATTS_EVT_WRITE event on our device (server)

Write request from peer (client) -> BLE_GATTS_EVT_RW_AUTHORIZE_REQUEST on our device (server)