diff --git a/include/usbd_gs_can.h b/include/usbd_gs_can.h
index 74d9372..6dc538b 100644
--- a/include/usbd_gs_can.h
+++ b/include/usbd_gs_can.h
@@ -10,3 +10,4 @@ uint8_t USBD_GS_CAN_Init(USBD_HandleTypeDef *pdev, queue_t *q_frame_pool, queue_
 void USBD_GS_CAN_SetChannel(USBD_HandleTypeDef *pdev, uint8_t channel, CAN_HandleTypeDef* handle);
 bool USBD_GS_CAN_TxReady(USBD_HandleTypeDef *pdev);
 uint8_t USBD_GS_CAN_Transmit(USBD_HandleTypeDef *pdev, uint8_t *buf, uint16_t len);
+uint8_t USBD_GS_CAN_PrepareReceive(USBD_HandleTypeDef *pdev);
diff --git a/src/main.c b/src/main.c
index 9ebfa98..203e716 100644
--- a/src/main.c
+++ b/src/main.c
@@ -23,7 +23,7 @@ queue_t *q_to_host;
 bool send_to_host_or_enqueue(struct gs_host_frame *frame)
 {
 	bool retval = false;
-	if (USBD_GS_CAN_Transmit(&hUSB, (uint8_t*)frame, sizeof(struct gs_host_frame))==USBD_OK) {
+	if ( USBD_GS_CAN_Transmit(&hUSB, (uint8_t*)frame, sizeof(struct gs_host_frame)) == USBD_OK ) {
 		queue_push_back(q_frame_pool, frame);
 		retval = true;
 	} else {
@@ -68,6 +68,7 @@ int main(void)
 
 		struct gs_host_frame *frame = queue_pop_front(q_from_host);
 		if (frame != 0) { // send can message from host
+			USBD_GS_CAN_PrepareReceive(&hUSB);
 
 			if (can_send(&hCAN, frame)) {
 				send_to_host_or_enqueue(frame);
diff --git a/src/usbd_conf.c b/src/usbd_conf.c
index 2bcbbe5..dee30eb 100644
--- a/src/usbd_conf.c
+++ b/src/usbd_conf.c
@@ -71,7 +71,7 @@ void HAL_PCD_MspInit(PCD_HandleTypeDef* hpcd)
     __HAL_RCC_USB_CLK_ENABLE();
 
     /* Peripheral interrupt init */
-    HAL_NVIC_SetPriority(USB_IRQn, 0, 0);
+    HAL_NVIC_SetPriority(USB_IRQn, 1, 0);
     HAL_NVIC_EnableIRQ(USB_IRQn);
   /* USER CODE BEGIN USB_MspInit 1 */
 
diff --git a/src/usbd_gs_can.c b/src/usbd_gs_can.c
index c4a504f..c6c6fdc 100644
--- a/src/usbd_gs_can.c
+++ b/src/usbd_gs_can.c
@@ -30,6 +30,10 @@ typedef struct {
 
 	CAN_HandleTypeDef *channels[NUM_CAN_CHANNEL];
 
+	uint32_t out_requests;
+	uint32_t out_requests_fail;
+	uint32_t out_requests_no_buf;
+
 } USBD_GS_CAN_HandleTypeDef __attribute__ ((aligned (4)));
 
 static uint8_t USBD_GS_CAN_Start(USBD_HandleTypeDef *pdev, uint8_t cfgidx);
@@ -40,8 +44,6 @@ static uint8_t USBD_GS_CAN_DataIn(USBD_HandleTypeDef *pdev, uint8_t epnum);
 static uint8_t *USBD_GS_CAN_GetCfgDesc(uint16_t *len);
 static uint8_t USBD_GS_CAN_DataOut(USBD_HandleTypeDef *pdev, uint8_t epnum);
 
-static uint8_t USBD_GS_CAN_PrepareReceive(USBD_HandleTypeDef *pdev);
-
 /* CAN interface class callbacks structure */
 USBD_ClassTypeDef USBD_GS_CAN = {
 	USBD_GS_CAN_Start,
@@ -319,14 +321,18 @@ static uint8_t USBD_GS_CAN_DataOut(USBD_HandleTypeDef *pdev, uint8_t epnum) {
 
 	USBD_GS_CAN_HandleTypeDef *hcan = (USBD_GS_CAN_HandleTypeDef*)pdev->pClassData;
 
+	hcan->out_requests++;
+
 	uint32_t rxlen = USBD_LL_GetRxDataSize(pdev, epnum);
 	if (rxlen >= sizeof(struct gs_host_frame)) {
 		queue_push_back_i(hcan->q_from_host, hcan->from_host_buf);
 		hcan->from_host_buf = queue_pop_front_i(hcan->q_frame_pool);
+		if (hcan->from_host_buf==0) {
+			// TODO handle buffers full condition - how?
+		}
 		retval = USBD_OK;
 	}
-
-	USBD_GS_CAN_PrepareReceive(pdev);
+	//USBD_GS_CAN_PrepareReceive(pdev);
     return retval;
 }
 
@@ -336,10 +342,10 @@ static uint8_t *USBD_GS_CAN_GetCfgDesc(uint16_t *len)
 	return USBD_GS_CAN_CfgDesc;
 }
 
-static uint8_t USBD_GS_CAN_PrepareReceive(USBD_HandleTypeDef *pdev)
+inline uint8_t USBD_GS_CAN_PrepareReceive(USBD_HandleTypeDef *pdev)
 {
 	USBD_GS_CAN_HandleTypeDef *hcan = (USBD_GS_CAN_HandleTypeDef*)pdev->pClassData;
-	return USBD_LL_PrepareReceive(pdev, GSUSB_ENDPOINT_OUT, hcan->from_host_buf, sizeof(struct gs_host_frame));
+	return USBD_LL_PrepareReceive(pdev, GSUSB_ENDPOINT_OUT, (uint8_t*)hcan->from_host_buf, sizeof(struct gs_host_frame));
 }
 
 bool USBD_GS_CAN_TxReady(USBD_HandleTypeDef *pdev)
@@ -358,5 +364,4 @@ uint8_t USBD_GS_CAN_Transmit(USBD_HandleTypeDef *pdev, uint8_t *buf, uint16_t le
 	} else {
 		return USBD_BUSY;
 	}
-
 }