From 360e04fa36ebcbcb1aa506820c8a89f209a28f3e Mon Sep 17 00:00:00 2001 From: Jimmy Durand Wesolowski Date: Mon, 2 Nov 2020 17:36:25 +0100 Subject: [PATCH] Fixing BLE GATT Characteristic notification and Characteristic Descriptor read (#4464) * BLERemoteChar: fix descriptor 2902 write for characteristic notifications When registering a notification on a characteristic, the 2902 descriptor (CCCD) value is set to 1 (or 2 for indication). According to the BLUETOOTH CORE SPECIFICATION Version 5.2, Revision Date 2019-12-31, section 4.12.3 "Write Characteristic Descriptors" (page 1588), the characteristic descriptor write must expect a response. Currently, the descriptor write is performed without expecting a reponse, which prevents the notification to be functional with some BLE stacks. This commit modify the write to expect the response. Signed-off-by: Jimmy Durand Wesolowski * BLERemoteChar: forward GATT client event to characteristic descriptors This commits prevents a permanent wait when calling BLERemoteDescriptor readValue function, on the m_semaphoreReadDescrEvt semaphore. ESP32 BLE stack calls to remote characteristic - notification, - value read - value write and remote characteristic descriptor - value read are asynchronous. When such a call is performed by this library, a semaphore is taken prior to the BLE stack read or write operation, and waited on after it. Releasing the semaphore is done by the characteristic event handling function (gattClientEventHandler), when the appropriate event is received. However, the characteristic descriptor events are discarded, and the value read semaphore is never released. This commits forwards the GATT client events from the remote characteristic down to their remote characteristic descriptor, and implements their event handling. Adding a semaphore for the remote characteristic descriptor value write will be done in a separate commit. Signed-off-by: Jimmy Durand Wesolowski * BLERemoteDescriptor: add semaphore to characteristic descriptor write This adds a semaphore to characteristic descriptor value write, to mimic the value read function, and to ensure completion of the operation before we carry on. Signed-off-by: Jimmy Durand Wesolowski Co-authored-by: Jimmy Durand Wesolowski --- libraries/BLE/src/BLERemoteCharacteristic.cpp | 11 ++++++++-- libraries/BLE/src/BLERemoteDescriptor.cpp | 21 +++++++++++++++++++ libraries/BLE/src/BLERemoteDescriptor.h | 3 ++- 3 files changed, 32 insertions(+), 3 deletions(-) diff --git a/libraries/BLE/src/BLERemoteCharacteristic.cpp b/libraries/BLE/src/BLERemoteCharacteristic.cpp index fbaae1a5..d6771044 100644 --- a/libraries/BLE/src/BLERemoteCharacteristic.cpp +++ b/libraries/BLE/src/BLERemoteCharacteristic.cpp @@ -237,6 +237,13 @@ void BLERemoteCharacteristic::gattClientEventHandler(esp_gattc_cb_event_t event, break; } // ESP_GATTC_WRITE_CHAR_EVT + case ESP_GATTC_READ_DESCR_EVT: + case ESP_GATTC_WRITE_DESCR_EVT: + for (auto &myPair : m_descriptorMap) { + myPair.second->gattClientEventHandler( + event, gattc_if, evtParam); + } + break; default: break; @@ -468,7 +475,7 @@ void BLERemoteCharacteristic::registerForNotify(notify_callback notifyCallback, if(!notifications) val[0] = 0x02; BLERemoteDescriptor* desc = getDescriptor(BLEUUID((uint16_t)0x2902)); if (desc != nullptr) - desc->writeValue(val, 2); + desc->writeValue(val, 2, true); } // End Register else { // If we weren't passed a callback function, then this is an unregistration. esp_err_t errRc = ::esp_ble_gattc_unregister_for_notify( @@ -484,7 +491,7 @@ void BLERemoteCharacteristic::registerForNotify(notify_callback notifyCallback, uint8_t val[] = {0x00, 0x00}; BLERemoteDescriptor* desc = getDescriptor((uint16_t)0x2902); if (desc != nullptr) - desc->writeValue(val, 2); + desc->writeValue(val, 2, true); } // End Unregister m_semaphoreRegForNotifyEvt.wait("registerForNotify"); diff --git a/libraries/BLE/src/BLERemoteDescriptor.cpp b/libraries/BLE/src/BLERemoteDescriptor.cpp index ad506aae..b1e0bef2 100644 --- a/libraries/BLE/src/BLERemoteDescriptor.cpp +++ b/libraries/BLE/src/BLERemoteDescriptor.cpp @@ -49,6 +49,23 @@ BLEUUID BLERemoteDescriptor::getUUID() { return m_uuid; } // getUUID +void BLERemoteDescriptor::gattClientEventHandler(esp_gattc_cb_event_t event, esp_gatt_if_t gattc_if, esp_ble_gattc_cb_param_t* evtParam) { + switch(event) { + case ESP_GATTC_READ_DESCR_EVT: + if (evtParam->read.handle != getHandle()) + break; + m_semaphoreReadDescrEvt.give(); + break; + + case ESP_GATTC_WRITE_DESCR_EVT: + if (evtParam->write.handle != getHandle()) + break; + m_semaphoreWriteDescrEvt.give(); + break; + default: + break; + } +} std::string BLERemoteDescriptor::readValue() { log_v(">> readValue: %s", toString().c_str()); @@ -137,6 +154,8 @@ void BLERemoteDescriptor::writeValue(uint8_t* data, size_t length, bool response return; } + m_semaphoreWriteDescrEvt.take("writeValue"); + esp_err_t errRc = ::esp_ble_gattc_write_char_descr( m_pRemoteCharacteristic->getRemoteService()->getClient()->getGattcIf(), m_pRemoteCharacteristic->getRemoteService()->getClient()->getConnId(), @@ -149,6 +168,8 @@ void BLERemoteDescriptor::writeValue(uint8_t* data, size_t length, bool response if (errRc != ESP_OK) { log_e("esp_ble_gattc_write_char_descr: %d", errRc); } + + m_semaphoreWriteDescrEvt.wait("writeValue"); log_v("<< writeValue"); } // writeValue diff --git a/libraries/BLE/src/BLERemoteDescriptor.h b/libraries/BLE/src/BLERemoteDescriptor.h index 29efe573..ebd847f2 100644 --- a/libraries/BLE/src/BLERemoteDescriptor.h +++ b/libraries/BLE/src/BLERemoteDescriptor.h @@ -35,7 +35,7 @@ public: void writeValue(std::string newValue, bool response = false); void writeValue(uint8_t newValue, bool response = false); void setAuth(esp_gatt_auth_req_t auth); - + void gattClientEventHandler(esp_gattc_cb_event_t event, esp_gatt_if_t gattc_if, esp_ble_gattc_cb_param_t* evtParam); private: friend class BLERemoteCharacteristic; @@ -49,6 +49,7 @@ private: std::string m_value; // Last received value of the descriptor. BLERemoteCharacteristic* m_pRemoteCharacteristic; // Reference to the Remote characteristic of which this descriptor is associated. FreeRTOS::Semaphore m_semaphoreReadDescrEvt = FreeRTOS::Semaphore("ReadDescrEvt"); + FreeRTOS::Semaphore m_semaphoreWriteDescrEvt = FreeRTOS::Semaphore("WriteDescrEvt"); esp_gatt_auth_req_t m_auth;