diff --git a/src/portable/raspberrypi/rp2040/dcd_rp2040.c b/src/portable/raspberrypi/rp2040/dcd_rp2040.c
index ccdbb9c01..c755c2e6f 100644
--- a/src/portable/raspberrypi/rp2040/dcd_rp2040.c
+++ b/src/portable/raspberrypi/rp2040/dcd_rp2040.c
@@ -201,7 +201,7 @@ static void hw_endpoint_init(uint8_t ep_addr, uint16_t wMaxPacketSize, uint8_t b
 static void hw_endpoint_xfer(uint8_t ep_addr, uint8_t *buffer, uint16_t total_bytes)
 {
     struct hw_endpoint *ep = hw_endpoint_get_by_addr(ep_addr);
-    _hw_endpoint_xfer_start(ep, buffer, total_bytes);
+    hw_endpoint_xfer_start(ep, buffer, total_bytes);
 }
 
 static void hw_handle_buff_status(void)
@@ -221,7 +221,7 @@ static void hw_handle_buff_status(void)
             // IN transfer for even i, OUT transfer for odd i
             struct hw_endpoint *ep = hw_endpoint_get_by_num(i >> 1u, !(i & 1u));
             // Continue xfer
-            bool done = _hw_endpoint_xfer_continue(ep);
+            bool done = hw_endpoint_xfer_continue(ep);
             if (done)
             {
                 // Notify
diff --git a/src/portable/raspberrypi/rp2040/hcd_rp2040.c b/src/portable/raspberrypi/rp2040/hcd_rp2040.c
index 561656a10..1ba9725fe 100644
--- a/src/portable/raspberrypi/rp2040/hcd_rp2040.c
+++ b/src/portable/raspberrypi/rp2040/hcd_rp2040.c
@@ -123,7 +123,7 @@ static void hw_xfer_complete(struct hw_endpoint *ep, xfer_result_t xfer_result)
 static void _handle_buff_status_bit(uint bit, struct hw_endpoint *ep)
 {
     usb_hw_clear->buf_status = bit;
-    bool done = _hw_endpoint_xfer_continue(ep);
+    bool done = hw_endpoint_xfer_continue(ep);
     if (done)
     {
         hw_xfer_complete(ep, XFER_RESULT_SUCCESS);
@@ -485,65 +485,6 @@ bool hcd_edpt_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_endpoint_t const
     return true;
 }
 
-// return true if double buffered
-static bool xfer_start(struct hw_endpoint *ep, uint8_t *buffer, uint16_t total_len)
-{
-  // Fill in info now that we're kicking off the hw
-  ep->total_len = total_len;
-  ep->len = 0;
-
-  // Limit by packet size
-  ep->user_buf = buffer;
-
-  // Buffer 0
-  ep->transfer_size = tu_min16(total_len, ep->wMaxPacketSize);
-  total_len -= ep->transfer_size;
-
-  // Buffer 1
-  ep->buf_1_len = tu_min16(total_len, ep->wMaxPacketSize);
-  total_len -= ep->buf_1_len;
-
-  ep->active = true;
-
-  // Write buffer control
-
-  // Buffer 0
-  uint32_t bufctrl = ep->transfer_size  | USB_BUF_CTRL_AVAIL;
-
-  // Copy data to DPB if tx
-  if (!ep->rx)
-  {
-    // Copy data from user buffer to hw buffer
-    memcpy(ep->hw_data_buf, ep->user_buf, ep->transfer_size + ep->buf_1_len);
-
-    // Mark as full
-    bufctrl |= USB_BUF_CTRL_FULL | (ep->buf_1_len ? (USB_BUF_CTRL_FULL << 16) : 0);
-  }
-
-  // PID
-  bufctrl |= ep->next_pid ? USB_BUF_CTRL_DATA1_PID : USB_BUF_CTRL_DATA0_PID;
-  ep->next_pid ^= 1u;
-
-  if (ep->buf_1_len)
-  {
-    bufctrl |= (ep->buf_1_len | USB_BUF_CTRL_AVAIL) << 16;
-    bufctrl |= (ep->next_pid ? USB_BUF_CTRL_DATA1_PID : USB_BUF_CTRL_DATA0_PID) << 16;
-    ep->next_pid ^= 1u;
-  }
-
-  // determine which buffer is last
-  if (total_len == 0)
-  {
-    bufctrl |= USB_BUF_CTRL_LAST << (ep->buf_1_len ? 16 : 0);
-  }
-
-  print_bufctrl32(bufctrl);
-
-  _hw_endpoint_buffer_control_set_value32(ep, bufctrl);
-
-  return ep->buf_1_len > 0;
-}
-
 bool hcd_edpt_xfer(uint8_t rhport, uint8_t dev_addr, uint8_t ep_addr, uint8_t * buffer, uint16_t buflen)
 {
     (void) rhport;
@@ -567,7 +508,7 @@ bool hcd_edpt_xfer(uint8_t rhport, uint8_t dev_addr, uint8_t ep_addr, uint8_t *
     // sie ctrl registers. Otherwise interrupt ep registers should
     // already be configured
     if (ep == &epx) {
-        _hw_endpoint_xfer_start(ep, buffer, buflen);
+        hw_endpoint_xfer_start(ep, buffer, buflen);
 
         // That has set up buffer control, endpoint control etc
         // for host we have to initiate the transfer
@@ -581,7 +522,7 @@ bool hcd_edpt_xfer(uint8_t rhport, uint8_t dev_addr, uint8_t ep_addr, uint8_t *
         usb_hw->sie_ctrl = flags;
     }else
     {
-      _hw_endpoint_xfer_start(ep, buffer, buflen);
+      hw_endpoint_xfer_start(ep, buffer, buflen);
     }
 
     return true;
diff --git a/src/portable/raspberrypi/rp2040/rp2040_usb.c b/src/portable/raspberrypi/rp2040/rp2040_usb.c
index 5f61f90c5..293325b8b 100644
--- a/src/portable/raspberrypi/rp2040/rp2040_usb.c
+++ b/src/portable/raspberrypi/rp2040/rp2040_usb.c
@@ -50,6 +50,13 @@ static inline void _hw_endpoint_update_last_buf(struct hw_endpoint *ep)
 }
 #endif
 
+//--------------------------------------------------------------------+
+//
+//--------------------------------------------------------------------+
+
+void _hw_endpoint_xfer_sync(struct hw_endpoint *ep);
+void _hw_endpoint_start_next_buffer(struct hw_endpoint *ep);
+
 void rp2040_usb_init(void)
 {
     // Reset usb controller
@@ -180,8 +187,7 @@ void _hw_endpoint_start_next_buffer(struct hw_endpoint *ep)
   _hw_endpoint_buffer_control_set_value32(ep, buf_ctrl);
 }
 
-
-void _hw_endpoint_xfer_start(struct hw_endpoint *ep, uint8_t *buffer, uint16_t total_len)
+void hw_endpoint_xfer_start(struct hw_endpoint *ep, uint8_t *buffer, uint16_t total_len)
 {
   _hw_endpoint_lock_update(ep, 1);
   pico_trace("Start transfer of total len %d on ep %d %s\n", total_len, tu_edpt_number(ep->ep_addr),
@@ -205,58 +211,34 @@ void _hw_endpoint_xfer_start(struct hw_endpoint *ep, uint8_t *buffer, uint16_t t
   _hw_endpoint_lock_update(ep, -1);
 }
 
-void _hw_endpoint_xfer_sync (struct hw_endpoint *ep)
+static void ep_sync_buf(struct hw_endpoint *ep, uint8_t buf_id)
 {
-  // Update hw endpoint struct with info from hardware
-  // after a buff status interrupt
+  uint32_t buf_ctrl = _hw_endpoint_buffer_control_get_value32(ep);
+  if (buf_id)  buf_ctrl = buf_ctrl >> 16;
 
-  uint32_t const buf_ctrl = _hw_endpoint_buffer_control_get_value32(ep);
-  print_bufctrl32(buf_ctrl);
+  uint16_t xferred_bytes = buf_ctrl & USB_BUF_CTRL_LEN_MASK;
 
-  // Transferred bytes for each buffer
-  uint16_t xferred_bytes[2];
-
-  xferred_bytes[0] = buf_ctrl & USB_BUF_CTRL_LEN_MASK;
-
-  // double buffered: take buffer1 into account as well
-  if ( (*ep->endpoint_control) & EP_CTRL_DOUBLE_BUFFERED_BITS )
-  {
-    xferred_bytes[1] = (buf_ctrl >> 16) & USB_BUF_CTRL_LEN_MASK;
-  }else
-  {
-    xferred_bytes[1] = 0;
-  }
-
-  TU_LOG_INT(2, xferred_bytes[0]);
-  TU_LOG_INT(2, xferred_bytes[1]);
-
-  // We are continuing a transfer here. If we are TX, we have successfully
-  // sent some data can increase the length we have sent
   if ( !ep->rx )
   {
+    // We are continuing a transfer here. If we are TX, we have successfully
+    // sent some data can increase the length we have sent
     assert(!(buf_ctrl & USB_BUF_CTRL_FULL));
-    ep->len += xferred_bytes[0] + xferred_bytes[1];
-  }
-  else
+
+    ep->len += xferred_bytes;
+  }else
   {
-    // If we are OUT we have recieved some data, so can increase the length
-    // we have recieved AFTER we have copied it to the user buffer at the appropriate offset
+    // If we have received some data, so can increase the length
+    // we have received AFTER we have copied it to the user buffer at the appropriate offset
     assert(buf_ctrl & USB_BUF_CTRL_FULL);
 
-    memcpy(&ep->user_buf[ep->len], ep->hw_data_buf, xferred_bytes[0]);
-    ep->len += xferred_bytes[0];
-
-    if (xferred_bytes[1])
-    {
-      memcpy(&ep->user_buf[ep->len], ep->hw_data_buf+64, xferred_bytes[1]);
-      ep->len += xferred_bytes[1];
-    }
+    memcpy(&ep->user_buf[ep->len], ep->hw_data_buf + buf_id*64, xferred_bytes);
+    ep->len += xferred_bytes;
   }
 
-  // Sometimes the host will send less data than we expect...
-  // If this is a short out transfer update the total length of the transfer
-  // to be the current length
-  if ( (ep->rx) && ((xferred_bytes[0] < ep->wMaxPacketSize) || (xferred_bytes[1] && (xferred_bytes[1] < ep->wMaxPacketSize))) )
+  // Short packet
+  // TODO what if we prepare double buffered but receive short packet on buffer 0 !!!
+  // would the buffer status  or trans complete interrupt is triggered
+  if (xferred_bytes < ep->wMaxPacketSize)
   {
     pico_trace("Short rx transfer\n");
     // Reduce total length as this is last packet
@@ -264,8 +246,23 @@ void _hw_endpoint_xfer_sync (struct hw_endpoint *ep)
   }
 }
 
+void _hw_endpoint_xfer_sync (struct hw_endpoint *ep)
+{
+  // Update hw endpoint struct with info from hardware
+  // after a buff status interrupt
+
+  // always sync buffer 0
+  ep_sync_buf(ep, 0);
+
+  // sync buffer 1 if double buffered
+  if ( (*ep->endpoint_control) & EP_CTRL_DOUBLE_BUFFERED_BITS )
+  {
+    ep_sync_buf(ep, 1);
+  }
+}
+
 // Returns true if transfer is complete
-bool _hw_endpoint_xfer_continue(struct hw_endpoint *ep)
+bool hw_endpoint_xfer_continue(struct hw_endpoint *ep)
 {
     _hw_endpoint_lock_update(ep, 1);
     // Part way through a transfer
diff --git a/src/portable/raspberrypi/rp2040/rp2040_usb.h b/src/portable/raspberrypi/rp2040/rp2040_usb.h
index d27f4157a..b3fcb9417 100644
--- a/src/portable/raspberrypi/rp2040/rp2040_usb.h
+++ b/src/portable/raspberrypi/rp2040/rp2040_usb.h
@@ -94,11 +94,9 @@ struct hw_endpoint
 
 void rp2040_usb_init(void);
 
+void hw_endpoint_xfer_start(struct hw_endpoint *ep, uint8_t *buffer, uint16_t total_len);
+bool hw_endpoint_xfer_continue(struct hw_endpoint *ep);
 void hw_endpoint_reset_transfer(struct hw_endpoint *ep);
-void _hw_endpoint_start_next_buffer(struct hw_endpoint *ep);
-void _hw_endpoint_xfer_start(struct hw_endpoint *ep, uint8_t *buffer, uint16_t total_len);
-void _hw_endpoint_xfer_sync(struct hw_endpoint *ep);
-bool _hw_endpoint_xfer_continue(struct hw_endpoint *ep);
 
 void _hw_endpoint_buffer_control_update32(struct hw_endpoint *ep, uint32_t and_mask, uint32_t or_mask);
 static inline uint32_t _hw_endpoint_buffer_control_get_value32(struct hw_endpoint *ep) {