Restore text sensors and prevent overflow (#8093)

* Fix FM sensor

radio/src/telemetry/crossfire.cpp

@@ -178,10 +178,9 @@ void processCrossfireTelemetryFrame()
     case FLIGHT_MODE_ID:
     {
       const CrossfireSensor & sensor = crossfireSensors[FLIGHT_MODE_INDEX];
-      for (int i=0; i<min<int>(16, telemetryRxBuffer[1]-2); i+=4) {
-        uint32_t value = *((uint32_t *)&telemetryRxBuffer[3+i]);
-        setTelemetryValue(PROTOCOL_TELEMETRY_CROSSFIRE, sensor.id, 0, sensor.subId, value, sensor.unit, i);
-      }
+      auto textLength = min<int>(16, telemetryRxBuffer[1] - 1);
+      telemetryRxBuffer[textLength] = '\0';
+      setTelemetryText(PROTOCOL_TELEMETRY_CROSSFIRE, sensor.id, 0, sensor.subId, (const char *)telemetryRxBuffer + 3);
       break;
     }
 

radio/src/telemetry/telemetry_sensors.cpp

@@ -204,6 +204,7 @@ void TelemetryItem::setValue(const TelemetrySensor & sensor, int32_t val, uint32
     }
   }
   else if (unit == UNIT_TEXT) {
+    // Should be handled at telemetry protocol level
     return;
   }
   else {

radio/src/telemetry/telemetry_sensors.h

@@ -26,6 +26,7 @@
 constexpr int8_t TELEMETRY_SENSOR_TIMEOUT_UNAVAILABLE = -2;
 constexpr int8_t TELEMETRY_SENSOR_TIMEOUT_OLD = -1;
 constexpr int8_t TELEMETRY_SENSOR_TIMEOUT_START = 125; // * 160ms = 20s
+constexpr uint8_t TELEMETRY_SENSOR_TEXT_LENGTH = 16;
 
 class TelemetryItem
 {
@@ -74,7 +75,7 @@ class TelemetryItem
         // pilot latitude is stored in max
         // distFromEarthAxis is stored in value
       } gps;
-      char text[16];
+      char text[TELEMETRY_SENSOR_TEXT_LENGTH];
     };
 
     TelemetryItem()