diff --git a/src/display.cpp b/src/display.cpp
index c3617538..b2fecf09 100644
--- a/src/display.cpp
+++ b/src/display.cpp
@@ -114,7 +114,7 @@ void refreshtheDisplay() {
 // update Battery status (line 2)
 #ifdef HAS_BATTERY_PROBE
   u8x8.setCursor(0, 2);
-  u8x8.printf("B:%.1fV", batt_voltage / 1000.0);
+  u8x8.printf(batt_voltage > 4000 ? "B:USB " : "B:%.1fV", batt_voltage / 1000.0);
 #endif
 
 // update GPS status (line 2)
diff --git a/src/globals.h b/src/globals.h
index 33548607..f064b258 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -37,6 +37,13 @@ typedef struct {
   char version[10];      // Firmware version
 } configData_t;
 
+// Struct holding payload for data send queue
+typedef struct {
+  uint8_t MessageSize;
+  uint8_t MessagePort;
+  uint8_t Message[PAYLOAD_BUFFER_SIZE];
+} MessageBuffer_t;
+
 // global variables
 extern configData_t cfg;                      // current device configuration
 extern char display_line6[], display_line7[]; // screen buffers
diff --git a/src/lorawan.cpp b/src/lorawan.cpp
index 7b6b3a74..ea0709ff 100644
--- a/src/lorawan.cpp
+++ b/src/lorawan.cpp
@@ -172,13 +172,13 @@ void onEvent(ev_t ev) {
     strcpy_P(buff, PSTR("JOINED"));
     sprintf(display_line6, " "); // clear previous lmic status
 
-    // set cyclic lmic link check to off because is not supported by ttn
-    // (but enabled by lmic after join)
-    LMIC_setLinkCheckMode(0);
-
     // set data rate adaptation according to saved setting
     LMIC_setAdrMode(cfg.adrmode);
-    
+
+    // set cyclic lmic link check to off if no ADR because is not supported by
+    // ttn (but enabled by lmic after join)
+    LMIC_setLinkCheckMode(cfg.adrmode);
+
     // Set data rate and transmit power (note: txpower seems to be ignored by
     // the library)
     switch_lora(cfg.lorasf, cfg.txpower);
diff --git a/src/main.cpp b/src/main.cpp
index dd826c2e..4f41ee09 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -109,8 +109,6 @@ void setup() {
 
 // initialize send queues for transmit channels
 #ifdef HAS_LORA
-  //--> LoraSendQueue = xQueueCreate(SEND_QUEUE_SIZE, sizeof(struct SendBuffer
-  //*));
   LoraSendQueue = xQueueCreate(SEND_QUEUE_SIZE, sizeof(MessageBuffer_t));
   if (LoraSendQueue == 0) {
     ESP_LOGE(TAG, "Could not create LORA send queue. Aborting.");
@@ -120,8 +118,6 @@ void setup() {
              SEND_QUEUE_SIZE * PAYLOAD_BUFFER_SIZE);
 #endif
 #ifdef HAS_SPI
-  //--> SPISendQueue = xQueueCreate(SEND_QUEUE_SIZE, sizeof(struct SendBuffer
-  //*));
   SPISendQueue = xQueueCreate(SEND_QUEUE_SIZE, sizeof(MessageBuffer_t));
   if (SPISendQueue == 0) {
     ESP_LOGE(TAG, "Could not create SPI send queue. Aborting.");
diff --git a/src/senddata.cpp b/src/senddata.cpp
index 748ae07d..767aa84b 100644
--- a/src/senddata.cpp
+++ b/src/senddata.cpp
@@ -1,26 +1,31 @@
 // Basic Config
 #include "globals.h"
 
-MessageBuffer_t SendBuffer;
-
 // put data to send in RTos Queues used for transmit over channels Lora and SPI
 void SendData(uint8_t port) {
 
+  int m1 = 0, m2 = 0;
+  m1 = ESP.getFreeHeap();
+
+  MessageBuffer_t SendBuffer;
+
   SendBuffer.MessageSize = payload.getSize();
   SendBuffer.MessagePort = PAYLOAD_ENCODER <= 2
-                               ? port
-                               : (PAYLOAD_ENCODER == 4 ? LPP2PORT : LPP1PORT);
+                                ? port
+                                : (PAYLOAD_ENCODER == 4 ? LPP2PORT : LPP1PORT);
   memcpy(SendBuffer.Message, payload.getBuffer(), payload.getSize());
 
   // enqueue message in LoRa send queue
 #ifdef HAS_LORA
-  if (xQueueSendToBack(LoraSendQueue, (void *)&SendBuffer, (TickType_t)0) == pdTRUE)
+  if (xQueueSendToBack(LoraSendQueue, (void *)&SendBuffer, (TickType_t)0) ==
+      pdTRUE)
     ESP_LOGI(TAG, "%d bytes enqueued to send on LoRa", payload.getSize());
 #endif
 
 // enqueue message in SPI send queue
 #ifdef HAS_SPI
-  if (xQueueSendToBack(SPISendQueue, (void *)&SendBuffer, (TickType_t)0) == pdTRUE)
+  if (xQueueSendToBack(SPISendQueue, (void *)&SendBuffer, (TickType_t)0) ==
+      pdTRUE)
     ESP_LOGI(TAG, "%d bytes enqueued to send on SPI", payload.getSize());
 #endif
 
@@ -31,10 +36,17 @@ void SendData(uint8_t port) {
     ESP_LOGI(TAG, "Counter cleared");
   }
 
+  m2 = ESP.getFreeHeap();
+  if (m2 - m1)
+    ESP_LOGI(TAG, "SendData            %d bytes", m2 - m1);
+
 } // SendData
 
 // cyclic called function to prepare payload to send
 void sendPayload() {
+
+  int m1 = 0, m2 = 0;
+  m1 = ESP.getFreeHeap();
   if (SendCycleTimerIRQ) {
     portENTER_CRITICAL(&timerMux);
     SendCycleTimerIRQ = 0;
@@ -65,6 +77,11 @@ void sendPayload() {
 #endif
     SendData(COUNTERPORT);
   }
+
+  m2 = ESP.getFreeHeap();
+  if (m2 - m1)
+    ESP_LOGI(TAG, "sendpayload         %d bytes", m2 - m1);
+
 } // sendpayload()
 
 // interrupt handler used for payload send cycle timer
@@ -77,27 +94,36 @@ void IRAM_ATTR SendCycleIRQ() {
 // cyclic called function to eat data from RTos send queues and transmit it
 void processSendBuffer() {
 
+  int m1 = 0, m2 = 0;
+  m1 = ESP.getFreeHeap();
+
+  MessageBuffer_t SendBuffer;
+
 #ifdef HAS_LORA
   // Check if there is a pending TX/RX job running
   if ((LMIC.opmode & (OP_JOINING | OP_REJOIN | OP_TXDATA | OP_POLL)) != 0) {
     // LoRa Busy -> don't eat data from queue, since it cannot be sent
   } else {
-    if (xQueueReceive(LoraSendQueue, &(SendBuffer), (TickType_t)0) == pdTRUE) {
+    if (xQueueReceive(LoraSendQueue, &SendBuffer, (TickType_t)0) == pdTRUE) {
       // SendBuffer gets struct MessageBuffer with next payload from queue
       LMIC_setTxData2(SendBuffer.MessagePort, SendBuffer.Message,
                       SendBuffer.MessageSize, (cfg.countermode & 0x02));
-      ESP_LOGI(TAG, "%d bytes sent to LORA", SendBuffer.MessageSize);
+      ESP_LOGI(TAG, "%d bytes sent to LoRa", SendBuffer.MessageSize);
       sprintf(display_line7, "PACKET QUEUED");
     }
   }
 #endif
 
 #ifdef HAS_SPI
-  if (xQueueReceive(SPISendQueue, &(SendBuffer), (TickType_t)0) == pdTRUE) {
+  if (xQueueReceive(SPISendQueue, &SendBuffer, (TickType_t)0) == pdTRUE) {
     ESP_LOGI(TAG, "%d bytes sent to SPI", SendBuffer.MessageSize);
   }
 #endif
 
+  m2 = ESP.getFreeHeap();
+  if (m2 - m1)
+    ESP_LOGI(TAG, "processSendBuffer   %d bytes", m2 - m1);
+
 } // processSendBuffer
 
 void flushQueues() {
diff --git a/src/senddata.h b/src/senddata.h
index e709cedc..806899d6 100644
--- a/src/senddata.h
+++ b/src/senddata.h
@@ -1,13 +1,6 @@
 #ifndef _SENDDATA_H
 #define _SENDDATA_H
 
-// Struct holding payload for data send queue
-typedef struct {
-  uint8_t MessageSize;
-  uint8_t MessagePort;
-  uint8_t Message[PAYLOAD_BUFFER_SIZE];
-} MessageBuffer_t;
-
 void SendData(uint8_t port);
 void sendPayload(void);
 void SendCycleIRQ(void);