disable LMIC onEvent()

src/lmic_config.h

@@ -21,7 +21,10 @@
 #define LMIC_USE_INTERRUPTS 1
 
 // time sync via LoRaWAN network, note: not supported by TTNv2
-// #define LMIC_ENABLE_DeviceTimeReq 1
+//#define LMIC_ENABLE_DeviceTimeReq 1
+
+// use callback event handlers, not onEvent() reference
+#define LMIC_ENABLE_onEvent 0
 
 // This tells LMIC to make the receive windows bigger, in case your clock is
 // faster or slower. This causes the transceiver to be earlier switched on,