Failure when calling discoverAttributes()

[michaelboeding]

I seem to be getting the following error when trying to have an esp32-s3 connect to another esp32-s3. Any ideas?

Scanning task is already running!
I (29920) BaseStation: Scanning task is already running!
I (29927) BaseStation: Waiting for event from the application queue
I (29967) NimBLE: GATT procedure initiated: discover all descriptors;
I (29968) NimBLE: chr_val_handle=5 end_handle=5
E (29969) NimBLERemoteCharacteristic: ble_gattc_disc_all_dscs: rc=3 One or more arguments are invalid.
E (29979) BluetoothConnection: Failed to discover attributes
I (30020) NimBLEClient: Connection parameters updated.

[h2zero]

Are you using the latest release?

[michaelboeding]

I am not - I was trying not to tear up my current code (this worked before). But I did change the connection parameters on the client since it is a low power device. Do you think moving to the latest would be helpful? It almost feels like maybe it's a timeout because the connection parameters are larger.

It is worth noting that I switched from an ESP32 to an ESP32-S3....seems somewhat related to this but it is closed

espressif/esp-idf#10109

Would the new API help with this? I disabled BLE 5.0 like the thread said and am running 5.3.1 of the ESP-Idf . @h2zero

[h2zero]

There was a bug related to this issue that was resolved in the latest release, please try that and let me know.

[michaelboeding]

Got it - will do thanks!

[michaelboeding]

Hey @h2zero updated to the new version and it seems to be working now. It wasn't very hard to upgrade either. Guess I should have just done that in the first place. That being said I did run into a new error that I think I have fixed below.

In NimBLERemoteCharacteristic.cpp it seems like the retrieveDescriptors() method will crash with a LoadProhibited error. I think this is happening because we are trying to access the m_vDescriptors.back() when it may be empty. I just added a check for this and everything seemed to work correctly.

// Only set the descriptor if we have any in the vector added by MB
if (!m_vDescriptors.empty()) {
    pFilter->dsc = m_vDescriptors.back();
} else {
    pFilter->dsc = nullptr;
}

Full updated method

/**
 * @brief Populate the descriptors (if any) for this characteristic.
 * @param [in] pFilter Pointer to a filter containing pointers to descriptor, UUID, and task data.
 * @return True if successfully retrieved, success = BLE_HS_EDONE.
 */
bool NimBLERemoteCharacteristic::retrieveDescriptors(NimBLEDescriptorFilter* pFilter) const {
    NIMBLE_LOGD(LOG_TAG, ">> retrieveDescriptors() for characteristic: %s", getUUID().toString().c_str());

    // If this is the last handle then there are no descriptors
    if (getHandle() == getRemoteService()->getEndHandle()) {
        NIMBLE_LOGD(LOG_TAG, "<< retrieveDescriptors(): found 0 descriptors.");
        return true;
    }

    NimBLETaskData         taskData(const_cast<NimBLERemoteCharacteristic*>(this));
    NimBLEDescriptorFilter defaultFilter{nullptr, nullptr, &taskData};
    if (pFilter == nullptr) {
        pFilter = &defaultFilter;
    }

    int rc = ble_gattc_disc_all_dscs(getClient()->getConnHandle(),
                                     getHandle(),
                                     getRemoteService()->getEndHandle(),
                                     NimBLERemoteCharacteristic::descriptorDiscCB,
                                     pFilter);
    if (rc != 0) {
        NIMBLE_LOGE(LOG_TAG, "ble_gattc_disc_all_dscs: rc=%d %s", rc, NimBLEUtils::returnCodeToString(rc));
        return false;
    }

    NimBLEUtils::taskWait(pFilter->taskData, BLE_NPL_TIME_FOREVER);
    rc = ((NimBLETaskData*)pFilter->taskData)->m_flags;
    if (rc != BLE_HS_EDONE) {
        NIMBLE_LOGE(LOG_TAG, "<< retrieveDescriptors(): failed: rc=%d %s", rc, NimBLEUtils::returnCodeToString(rc));
        return false;
    }

    // Only set the descriptor if we have any in the vector added by MB
    if (!m_vDescriptors.empty()) {
        pFilter->dsc = m_vDescriptors.back();
    } else {
        pFilter->dsc = nullptr;
    }
    
    NIMBLE_LOGD(LOG_TAG, "<< retrieveDescriptors(): found %d descriptors.", m_vDescriptors.size());
    return true;
} // retrieveDescriptors

Sorry it took me so long to get around to testing this - I have been very busy.

[h2zero]

Thanks @michaelboeding! I took a slightly different approach in #310 if you would like to test it.

[michaelboeding]

That should work also! I'll go ahead and close this