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Fixing BLE GATT Characteristic notification and Characteristic Descriptor read (#4464)

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* 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 <jimmy.durand.wesolowski@commsolid.com>

* 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 <jimmy.durand.wesolowski@commsolid.com>

* 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 <jimmy.durand.wesolowski@commsolid.com>

Co-authored-by: Jimmy Durand Wesolowski <jimmy.durand.wesolowski@commsolid.com>
This commit is contained in:
Jimmy Durand Wesolowski 2020-11-02 17:36:25 +01:00 committed by GitHub
parent 57145ade6f
commit 360e04fa36
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 32 additions and 3 deletions
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11
libraries/BLE/src/BLERemoteCharacteristic.cpp
View File

@ -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");

21
libraries/BLE/src/BLERemoteDescriptor.cpp
View File

@ -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

3
libraries/BLE/src/BLERemoteDescriptor.h
View File

@ -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;