Experiment with BLE

- clarify documentation how the close pass event service reports data
- initialize close pass & distance service with empty event

Author: amandel

docs/software/firmware/bluetooth_services.md

@@ -97,10 +97,7 @@ Might get removed soon, prefer the "OBS Service".
 | ------------------- | -------------------------------------- | --------------- | ----------------------------------------------------------------------------------- |
 | Close Pass Events   | `1FE7FAF9-CE63-4236-0003-000000000002` | `READ`,`NOTIFY` | Notifies of new close pass events                                                   |
 
-The format of the transmitted string for the *distance characteristic* is `"timestamp;[leftSensor1, leftSensor2, ...];[rightSensor1, rightSensor2, ...]"`, e.g. `"43567893;100,30;400"` or `"43567893;100;"`.
-The list of sensor values for one side might be empty, but the entire transmitted string can be safely split on `";"` and each sensor value list safely on `","`.
-
-The format of the transmitted string for the *event characteristic* is `"timestamp;eventName;[payload1, payload2, ...]"`, e.g. `"43567893;button;"` or `"43567893;avg2s;142,83"`.
+The format of the transmitted string for the *Close Pass Events* is `"timestamp;eventName;[payload1, payload2, ...]"`, e.g. `"43567893;button;123"`.
 The following events are defined:
 * `button`: Triggered using a physical button
   * Payload: last distance value

src/bluetooth/ClosePassService.cpp

@@ -26,6 +26,7 @@
 void ClosePassService::setup(BLEServer *pServer) {
   mService = pServer->createService(SERVICE_CLOSEPASS_UUID);
   mEventCharacteristic = mService->createCharacteristic(SERVICE_CLOSEPASS_CHAR_EVENT_UUID, BLECharacteristic::PROPERTY_READ | BLECharacteristic::PROPERTY_NOTIFY);
+  mEventCharacteristic->setValue((String(millis()) + ";button;").c_str());
 }
 
 bool ClosePassService::shouldAdvertise() {
@@ -37,7 +38,7 @@ BLEService* ClosePassService::getService() {
 }
 
 void ClosePassService::newPassEvent(const uint32_t millis, const uint16_t leftValue, const uint16_t rightValue) {
-  auto transmitValue = String(millis) + ";button;" + valueAsString(leftValue) + ";" + valueAsString(rightValue);
+  auto transmitValue = String(millis) + ";button;" + valueAsString(leftValue);
   mEventCharacteristic->setValue(transmitValue.c_str());
   mEventCharacteristic->notify();
 }

src/bluetooth/DistanceService.cpp

@@ -27,6 +27,7 @@ void DistanceService::setup(BLEServer *pServer) {
   mService = pServer->createService(SERVICE_DISTANCE_UUID);
   mCharacteristic = mService->createCharacteristic(SERVICE_DISTANCE_CHAR_50MS_UUID, BLECharacteristic::PROPERTY_READ | BLECharacteristic::PROPERTY_NOTIFY);
 // SimRa does not like BLE2902
+  mCharacteristic->setValue((String(millis()) + ";;").c_str());
 }
 
 bool DistanceService::shouldAdvertise() {