diff --git a/firmware/target/arm/rk27xx/usb-drv-rk27xx.c b/firmware/target/arm/rk27xx/usb-drv-rk27xx.c
index 810c793..d12187c 100644
--- a/firmware/target/arm/rk27xx/usb-drv-rk27xx.c
+++ b/firmware/target/arm/rk27xx/usb-drv-rk27xx.c
@@ -203,15 +203,30 @@ static void blk_read(int ep)
 {
     int ep_num = EP_NUM(ep);
     int xfer_size = BOUT_RXSTAT(ep_num) & 0xffff;
+    int max = usb_drv_port_speed() ? 512 : 64;
+    struct endpoint_t *endp = &endpoints[ep_num];
     
     /* clear NAK bit */
     BOUT_RXCON(ep_num) &= ~RXNAK;
  
-    endpoints[ep_num].cnt -= xfer_size;
-    endpoints[ep_num].buf += xfer_size;
-   
-    BOUT_DMAOUTLMADDR(ep_num) = (uint32_t)endpoints[ep_num].buf;
-    BOUT_DMAOUTCTL(ep_num) = DMA_START;
+    endp->cnt -= xfer_size;
+    endp->buf += xfer_size;
+
+    /* if the transfer was short or if the total count is zero, transfer is complete */
+    if (endp->cnt == 0 || xfer_size < max)
+    {
+        logf("udc_intr: usb_core_transfer_complete(0x%x, USB_DIR_OUT, 0, 0x%x), %ld", ep_num, endp->len, current_tick);
+        usb_core_transfer_complete(ep_num,      /* ep */
+                                    USB_DIR_OUT, /* dir */
+                                    0,           /* status */
+                                    endp->len - endp->cnt);    /* length */
+        endp->cnt = 0;
+    }
+    else
+    {
+        BOUT_DMAOUTLMADDR(ep_num) = (uint32_t)endp->buf;
+        BOUT_DMAOUTCTL(ep_num) = DMA_START;
+    }
 }
 
 static void int_write(int ep)
@@ -419,21 +434,10 @@ void INT_UDC(void)
                             rxstat = BOUT_RXSTAT(ep_num);
             
                             /* TODO handle errors */
-                            if (rxstat & RXACK) /* RxACK */
+                            if (rxstat & RXACK && ep->cnt > 0) /* RxACK */
                             {
-                                if (ep->cnt > 0)
-                                {
-                                    logf("udc_intr: blk_read(0x%x), %ld", ep_num, current_tick);
-                                    blk_read(ep_num);
-                                }
-                                else
-                                {
-                                    logf("udc_intr: usb_core_transfer_complete(0x%x, USB_DIR_OUT, 0, 0x%x), %ld", ep_num, ep->len, current_tick);
-                                    usb_core_transfer_complete(ep_num,      /* ep */
-                                                               USB_DIR_OUT, /* dir */
-                                                               0,           /* status */
-                                                               ep->len);    /* length */
-                                }
+                                logf("udc_intr: blk_read(0x%x), %ld", ep_num, current_tick);
+                                blk_read(ep_num);
                             }
                         }
                         else
@@ -534,15 +538,15 @@ int usb_drv_request_endpoint(int type, int dir)
 
             if (ep_num%3 == 0) /* IIN 3, 6, 9, 12, 15 */
             {
-                IIN_TXCON(ep_num) = (ep_num<<8)|TXEPEN|TXNAK; /* ep_num, enable, NAK */
+                IIN_TXCON(ep_num) = (ep_num<<8)|TXEPEN|TXNAK|TXACKINTEN; /* ep_num, enable, NAK */
             }
             else if (ep_num%3 == 1) /* BOUT 1, 4, 7, 10, 13 */
             {
-                BOUT_RXCON(ep_num) = (ep_num<<8)|RXEPEN|RXNAK; /* ep_num, NAK, enable */
+                BOUT_RXCON(ep_num) = (ep_num<<8)|RXEPEN|RXNAK|RXACKINTEN; /* ep_num, NAK, enable */
             }
             else if (ep_num%3 == 2) /* BIN 2, 5, 8, 11, 14 */
             {
-                BIN_TXCON(ep_num) = (ep_num<<8)|TXEPEN|TXNAK; /* ep_num, enable, NAK */
+                BIN_TXCON(ep_num) = (ep_num<<8)|TXEPEN|TXNAK|TXACKINTEN; /* ep_num, enable, NAK */
             }
 
             /* enable interrupt from this endpoint */