setValue() notifies twice

[vovagorodok]

In https://github.com/vovagorodok/ArduinoBleOTA/blob/main/src/ArduinoBleOtaClass.cpp:

BLECharacteristic txCharacteristic(BLE_OTA_CHARACTERISTIC_UUID_TX, BLERead | BLENotify, BLE_OTA_MAX_ATTR_SIZE);
...
txCharacteristic.setValue(data, length);

notifies twice about written value.
Checked on esp32dev and nano_33_iot

[vovagorodok]

Can't find the reason in ArduinoBLE code. Any idea why it happens? In the same scenario with NimBLE-Arduino lib I have one notification. With this issue I can't implement ArduinoBleOTA lib correctly

[osemenyuk-114]

Hi! I faced a similar issue. After some investigations, I suppressed echoing data back to the client.
To implement this change you need to add BLEWriteWithoutResponse to the BLE Characteristics permissions and update code for void BLELocalCharacteristic::writeValue(BLEDevice device, const uint8_t value[], int length) function in src/local/BLELocalCharacteristic.cpp file.

--- a/src/local/BLELocalCharacteristic.cpp
+++ b/src/local/BLELocalCharacteristic.cpp
@@ -223,7 +223,17 @@ void BLELocalCharacteristic::writeValue(BLEDevice device, const uint8_t value[],
 {
   _written = true;

-  writeValue(value, length);
+  if (_properties & BLEWriteWithoutResponse) {
+    _valueLength = min(length, _valueSize);
+    memcpy(_value, value, _valueLength);
+
+    if (_fixedLength) {
+      _valueLength = _valueSize;
+    }
+  }
+  else {
+    writeValue(value, length);
+  }

   if (_eventHandlers[BLEWritten]) {
     _eventHandlers[BLEWritten](device, BLECharacteristic(this));