diff --git a/examples/device/cdc_msc/src/main.c b/examples/device/cdc_msc/src/main.c
index e4a205533..06a4f732f 100644
--- a/examples/device/cdc_msc/src/main.c
+++ b/examples/device/cdc_msc/src/main.c
@@ -124,6 +124,7 @@ void cdc_task(void) {
 
     if ((btn_prev == 0u) && (btn != 0u)) {
       uart_state.dsr ^= 1;
+      uart_state.dcd ^= 1;
       tud_cdc_notify_uart_state(&uart_state);
     }
     btn_prev = btn;
diff --git a/examples/device/webusb_serial/src/main.c b/examples/device/webusb_serial/src/main.c
index 0c2acd94e..4fcddd724 100644
--- a/examples/device/webusb_serial/src/main.c
+++ b/examples/device/webusb_serial/src/main.c
@@ -101,7 +101,7 @@ int main(void) {
 
   while (1) {
     tud_task(); // tinyusb device task
-    cdc_task();
+    tud_cdc_write_flush();
     led_blinking_task();
   }
 }
@@ -116,13 +116,7 @@ static void echo_all(const uint8_t buf[], uint32_t count) {
 
   // echo to cdc
   if (tud_cdc_connected()) {
-    for (uint32_t i = 0; i < count; i++) {
-      tud_cdc_write_char(buf[i]);
-      if (buf[i] == '\r') {
-        tud_cdc_write_char('\n');
-      }
-    }
-    tud_cdc_write_flush();
+    tud_cdc_write(buf, count);
   }
 }
 
@@ -162,7 +156,9 @@ void tud_resume_cb(void) {
 // return false to stall control endpoint (e.g unsupported request)
 bool tud_vendor_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const* request) {
   // nothing to with DATA & ACK stage
-  if (stage != CONTROL_STAGE_SETUP) return true;
+  if (stage != CONTROL_STAGE_SETUP) {
+    return true;
+  }
 
   switch (request->bmRequestType_bit.type) {
     case TUSB_REQ_TYPE_VENDOR:
@@ -215,33 +211,20 @@ bool tud_vendor_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_requ
   return false;
 }
 
-void tud_vendor_rx_cb(uint8_t itf, uint8_t const* buffer, uint16_t bufsize) {
-  (void) itf;
+void tud_vendor_rx_cb(uint8_t idx, const uint8_t *buffer, uint16_t bufsize) {
+  (void)idx;
+
+// since we used data without pulling it from RX FIFO, we need to discard number of items used
+#if CFG_TUD_VENDOR_RX_BUFSIZE > 0
+  tud_vendor_read_discard(bufsize);
+#endif
 
   echo_all(buffer, bufsize);
-
-  // if using RX buffered is enabled, we need to flush the buffer to make room for new data
-  #if CFG_TUD_VENDOR_RX_BUFSIZE > 0
-  tud_vendor_read_flush();
-  #endif
 }
 
 //--------------------------------------------------------------------+
 // USB CDC
 //--------------------------------------------------------------------+
-void cdc_task(void) {
-  if (tud_cdc_connected()) {
-    // connected and there are data available
-    if (tud_cdc_available()) {
-      uint8_t buf[64];
-
-      uint32_t count = tud_cdc_read(buf, sizeof(buf));
-
-      // echo back to both web serial and cdc
-      echo_all(buf, count);
-    }
-  }
-}
 
 // Invoked when cdc when line state changed e.g connected/disconnected
 void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts) {
@@ -255,8 +238,13 @@ void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts) {
 }
 
 // Invoked when CDC interface received data from host
-void tud_cdc_rx_cb(uint8_t itf) {
-  (void)itf;
+void tud_cdc_rx_cb(uint8_t idx) {
+  (void)idx;
+  while (tud_cdc_available()) {
+    uint8_t        buf[64];
+    const uint32_t count = tud_cdc_read(buf, sizeof(buf));
+    echo_all(buf, count); // echo back to both web serial and cdc
+  }
 }
 
 //--------------------------------------------------------------------+
@@ -267,7 +255,9 @@ void led_blinking_task(void) {
   static bool led_state = false;
 
   // Blink every interval ms
-  if (board_millis() - start_ms < blink_interval_ms) return; // not enough time
+  if (board_millis() - start_ms < blink_interval_ms) {
+    return; // not enough time
+  }
   start_ms += blink_interval_ms;
 
   board_led_write(led_state);
diff --git a/src/class/vendor/vendor_device.c b/src/class/vendor/vendor_device.c
index c7903375d..c2393c25d 100644
--- a/src/class/vendor/vendor_device.c
+++ b/src/class/vendor/vendor_device.c
@@ -42,22 +42,20 @@ typedef struct {
 
   /*------------- From this point, data is not cleared by bus reset -------------*/
   struct {
-    tu_edpt_stream_t stream;
-    #if CFG_TUD_VENDOR_TX_BUFSIZE > 0
-    uint8_t ff_buf[CFG_TUD_VENDOR_TX_BUFSIZE];
-    #endif
-  } tx;
+    tu_edpt_stream_t tx;
+    tu_edpt_stream_t rx;
 
-  struct {
-    tu_edpt_stream_t stream;
-    #if CFG_TUD_VENDOR_RX_BUFSIZE > 0
-    uint8_t ff_buf[CFG_TUD_VENDOR_RX_BUFSIZE];
-    #endif
-  } rx;
+  #if CFG_TUD_VENDOR_TX_BUFSIZE > 0
+    uint8_t tx_ff_buf[CFG_TUD_VENDOR_TX_BUFSIZE];
+  #endif
 
+  #if CFG_TUD_VENDOR_RX_BUFSIZE > 0
+    uint8_t rx_ff_buf[CFG_TUD_VENDOR_RX_BUFSIZE];
+  #endif
+  } stream;
 } vendord_interface_t;
 
-#define ITF_MEM_RESET_SIZE   (offsetof(vendord_interface_t, itf_num) + sizeof(((vendord_interface_t *)0)->itf_num))
+#define ITF_MEM_RESET_SIZE (offsetof(vendord_interface_t, itf_num) + sizeof(((vendord_interface_t *)0)->itf_num))
 
 static vendord_interface_t _vendord_itf[CFG_TUD_VENDOR];
 
@@ -71,14 +69,14 @@ CFG_TUD_MEM_SECTION static vendord_epbuf_t _vendord_epbuf[CFG_TUD_VENDOR];
 //--------------------------------------------------------------------+
 // Weak stubs: invoked if no strong implementation is available
 //--------------------------------------------------------------------+
-TU_ATTR_WEAK void tud_vendor_rx_cb(uint8_t itf, uint8_t const* buffer, uint16_t bufsize) {
-  (void) itf;
+TU_ATTR_WEAK void tud_vendor_rx_cb(uint8_t idx, const uint8_t *buffer, uint16_t bufsize) {
+  (void)idx;
   (void) buffer;
   (void) bufsize;
 }
 
-TU_ATTR_WEAK void tud_vendor_tx_cb(uint8_t itf, uint32_t sent_bytes) {
-  (void) itf;
+TU_ATTR_WEAK void tud_vendor_tx_cb(uint8_t idx, uint32_t sent_bytes) {
+  (void)idx;
   (void) sent_bytes;
 }
 
@@ -86,59 +84,65 @@ TU_ATTR_WEAK void tud_vendor_tx_cb(uint8_t itf, uint32_t sent_bytes) {
 // Application API
 //--------------------------------------------------------------------
 
-bool tud_vendor_n_mounted(uint8_t itf) {
-  TU_VERIFY(itf < CFG_TUD_VENDOR);
-  vendord_interface_t* p_itf = &_vendord_itf[itf];
-  return p_itf->rx.stream.ep_addr || p_itf->tx.stream.ep_addr;
+bool tud_vendor_n_mounted(uint8_t idx) {
+  TU_VERIFY(idx < CFG_TUD_VENDOR);
+  vendord_interface_t *p_itf = &_vendord_itf[idx];
+  return p_itf->stream.rx.ep_addr || p_itf->stream.tx.ep_addr;
 }
 
 //--------------------------------------------------------------------+
 // Read API
 //--------------------------------------------------------------------+
-uint32_t tud_vendor_n_available(uint8_t itf) {
-  TU_VERIFY(itf < CFG_TUD_VENDOR, 0);
-  vendord_interface_t* p_itf = &_vendord_itf[itf];
-  return tu_edpt_stream_read_available(&p_itf->rx.stream);
+uint32_t tud_vendor_n_available(uint8_t idx) {
+  TU_VERIFY(idx < CFG_TUD_VENDOR, 0);
+  vendord_interface_t *p_itf = &_vendord_itf[idx];
+  return tu_edpt_stream_read_available(&p_itf->stream.rx);
 }
 
-bool tud_vendor_n_peek(uint8_t itf, uint8_t* u8) {
-  TU_VERIFY(itf < CFG_TUD_VENDOR);
-  vendord_interface_t* p_itf = &_vendord_itf[itf];
-  return tu_edpt_stream_peek(&p_itf->rx.stream, u8);
+bool tud_vendor_n_peek(uint8_t idx, uint8_t *u8) {
+  TU_VERIFY(idx < CFG_TUD_VENDOR);
+  vendord_interface_t *p_itf = &_vendord_itf[idx];
+  return tu_edpt_stream_peek(&p_itf->stream.rx, u8);
 }
 
-uint32_t tud_vendor_n_read (uint8_t itf, void* buffer, uint32_t bufsize) {
-  TU_VERIFY(itf < CFG_TUD_VENDOR, 0);
-  vendord_interface_t* p_itf = &_vendord_itf[itf];
-  return tu_edpt_stream_read(p_itf->rhport, &p_itf->rx.stream, buffer, bufsize);
+uint32_t tud_vendor_n_read(uint8_t idx, void *buffer, uint32_t bufsize) {
+  TU_VERIFY(idx < CFG_TUD_VENDOR, 0);
+  vendord_interface_t *p_itf = &_vendord_itf[idx];
+  return tu_edpt_stream_read(p_itf->rhport, &p_itf->stream.rx, buffer, bufsize);
 }
 
-void tud_vendor_n_read_flush (uint8_t itf) {
-  TU_VERIFY(itf < CFG_TUD_VENDOR, );
-  vendord_interface_t* p_itf = &_vendord_itf[itf];
-  tu_edpt_stream_clear(&p_itf->rx.stream);
-  tu_edpt_stream_read_xfer(p_itf->rhport, &p_itf->rx.stream);
+uint32_t tud_vendor_n_read_discard(uint8_t idx, uint32_t count) {
+  TU_VERIFY(idx < CFG_TUD_VENDOR, 0);
+  vendord_interface_t *p_itf = &_vendord_itf[idx];
+  return tu_edpt_stream_discard(&p_itf->stream.rx, count);
+}
+
+void tud_vendor_n_read_flush(uint8_t idx) {
+  TU_VERIFY(idx < CFG_TUD_VENDOR, );
+  vendord_interface_t *p_itf = &_vendord_itf[idx];
+  tu_edpt_stream_clear(&p_itf->stream.rx);
+  tu_edpt_stream_read_xfer(p_itf->rhport, &p_itf->stream.rx);
 }
 
 //--------------------------------------------------------------------+
 // Write API
 //--------------------------------------------------------------------+
-uint32_t tud_vendor_n_write (uint8_t itf, const void* buffer, uint32_t bufsize) {
-  TU_VERIFY(itf < CFG_TUD_VENDOR, 0);
-  vendord_interface_t* p_itf = &_vendord_itf[itf];
-  return tu_edpt_stream_write(p_itf->rhport, &p_itf->tx.stream, buffer, (uint16_t)bufsize);
+uint32_t tud_vendor_n_write(uint8_t idx, const void *buffer, uint32_t bufsize) {
+  TU_VERIFY(idx < CFG_TUD_VENDOR, 0);
+  vendord_interface_t *p_itf = &_vendord_itf[idx];
+  return tu_edpt_stream_write(p_itf->rhport, &p_itf->stream.tx, buffer, (uint16_t)bufsize);
 }
 
-uint32_t tud_vendor_n_write_flush (uint8_t itf) {
-  TU_VERIFY(itf < CFG_TUD_VENDOR, 0);
-  vendord_interface_t* p_itf = &_vendord_itf[itf];
-  return tu_edpt_stream_write_xfer(p_itf->rhport, &p_itf->tx.stream);
+uint32_t tud_vendor_n_write_flush(uint8_t idx) {
+  TU_VERIFY(idx < CFG_TUD_VENDOR, 0);
+  vendord_interface_t *p_itf = &_vendord_itf[idx];
+  return tu_edpt_stream_write_xfer(p_itf->rhport, &p_itf->stream.tx);
 }
 
-uint32_t tud_vendor_n_write_available (uint8_t itf) {
-  TU_VERIFY(itf < CFG_TUD_VENDOR, 0);
-  vendord_interface_t* p_itf = &_vendord_itf[itf];
-  return tu_edpt_stream_write_available(p_itf->rhport, &p_itf->tx.stream);
+uint32_t tud_vendor_n_write_available(uint8_t idx) {
+  TU_VERIFY(idx < CFG_TUD_VENDOR, 0);
+  vendord_interface_t *p_itf = &_vendord_itf[idx];
+  return tu_edpt_stream_write_available(p_itf->rhport, &p_itf->stream.tx);
 }
 
 //--------------------------------------------------------------------+
@@ -152,32 +156,30 @@ void vendord_init(void) {
     vendord_epbuf_t* p_epbuf = &_vendord_epbuf[i];
 
   #if CFG_TUD_VENDOR_RX_BUFSIZE > 0
-    uint8_t *rx_ff_buf = p_itf->rx.ff_buf;
+    uint8_t *rx_ff_buf = p_itf->stream.rx_ff_buf;
   #else
     uint8_t *rx_ff_buf = NULL;
   #endif
 
-    tu_edpt_stream_init(&p_itf->rx.stream, false, false, false,
-                        rx_ff_buf, CFG_TUD_VENDOR_RX_BUFSIZE,
-                        p_epbuf->epout, CFG_TUD_VENDOR_EPSIZE);
+    tu_edpt_stream_init(&p_itf->stream.rx, false, false, false, rx_ff_buf, CFG_TUD_VENDOR_RX_BUFSIZE, p_epbuf->epout,
+                        CFG_TUD_VENDOR_EPSIZE);
 
   #if CFG_TUD_VENDOR_TX_BUFSIZE > 0
-    uint8_t *tx_ff_buf = p_itf->tx.ff_buf;
+    uint8_t *tx_ff_buf = p_itf->stream.tx_ff_buf;
   #else
-    uint8_t* tx_ff_buf = NULL;
+    uint8_t *tx_ff_buf = NULL;
   #endif
 
-    tu_edpt_stream_init(&p_itf->tx.stream, false, true, false,
-                        tx_ff_buf, CFG_TUD_VENDOR_TX_BUFSIZE,
-                        p_epbuf->epin, CFG_TUD_VENDOR_EPSIZE);
+    tu_edpt_stream_init(&p_itf->stream.tx, false, true, false, tx_ff_buf, CFG_TUD_VENDOR_TX_BUFSIZE, p_epbuf->epin,
+                        CFG_TUD_VENDOR_EPSIZE);
   }
 }
 
 bool vendord_deinit(void) {
   for(uint8_t i=0; i<CFG_TUD_VENDOR; i++) {
     vendord_interface_t* p_itf = &_vendord_itf[i];
-    tu_edpt_stream_deinit(&p_itf->rx.stream);
-    tu_edpt_stream_deinit(&p_itf->tx.stream);
+    tu_edpt_stream_deinit(&p_itf->stream.rx);
+    tu_edpt_stream_deinit(&p_itf->stream.tx);
   }
   return true;
 }
@@ -188,30 +190,42 @@ void vendord_reset(uint8_t rhport) {
   for(uint8_t i=0; i<CFG_TUD_VENDOR; i++) {
     vendord_interface_t* p_itf = &_vendord_itf[i];
     tu_memclr(p_itf, ITF_MEM_RESET_SIZE);
-    tu_edpt_stream_clear(&p_itf->rx.stream);
-    tu_edpt_stream_close(&p_itf->rx.stream);
 
-    tu_edpt_stream_clear(&p_itf->tx.stream);
-    tu_edpt_stream_close(&p_itf->tx.stream);
+    tu_edpt_stream_clear(&p_itf->stream.rx);
+    tu_edpt_stream_close(&p_itf->stream.rx);
+
+    tu_edpt_stream_clear(&p_itf->stream.tx);
+    tu_edpt_stream_close(&p_itf->stream.tx);
   }
 }
 
-uint16_t vendord_open(uint8_t rhport, const tusb_desc_interface_t* desc_itf, uint16_t max_len) {
+// Find vendor interface by endpoint address
+static uint8_t find_vendor_itf(uint8_t ep_addr) {
+  for (uint8_t idx = 0; idx < CFG_TUD_VENDOR; idx++) {
+    const vendord_interface_t *p_vendor = &_vendord_itf[idx];
+    if (ep_addr == 0) {
+      // find unused: require both ep == 0
+      if (p_vendor->stream.rx.ep_addr == 0 && p_vendor->stream.tx.ep_addr == 0) {
+        return idx;
+      }
+    } else if (ep_addr == p_vendor->stream.rx.ep_addr || ep_addr == p_vendor->stream.tx.ep_addr) {
+      return idx;
+    } else {
+      // nothing to do
+    }
+  }
+  return 0xff;
+}
+
+uint16_t vendord_open(uint8_t rhport, const tusb_desc_interface_t *desc_itf, uint16_t max_len) {
   TU_VERIFY(TUSB_CLASS_VENDOR_SPECIFIC == desc_itf->bInterfaceClass, 0);
   const uint8_t* desc_end = (const uint8_t*)desc_itf + max_len;
   const uint8_t* p_desc = tu_desc_next(desc_itf);
 
   // Find available interface
-  vendord_interface_t* p_vendor = NULL;
-  uint8_t itf;
-  for(itf=0; itf<CFG_TUD_VENDOR; itf++) {
-    if (!tud_vendor_n_mounted(itf)) {
-      p_vendor = &_vendord_itf[itf];
-      break;
-    }
-  }
-  TU_VERIFY(p_vendor, 0);
-
+  const uint8_t idx = find_vendor_itf(0);
+  TU_ASSERT(idx < CFG_TUD_VENDOR, 0);
+  vendord_interface_t *p_vendor = &_vendord_itf[idx];
   p_vendor->rhport  = rhport;
   p_vendor->itf_num = desc_itf->bInterfaceNumber;
 
@@ -225,13 +239,13 @@ uint16_t vendord_open(uint8_t rhport, const tusb_desc_interface_t* desc_itf, uin
 
       // open endpoint stream, skip if already opened (multiple IN/OUT endpoints)
       if (tu_edpt_dir(desc_ep->bEndpointAddress) == TUSB_DIR_IN) {
-        tu_edpt_stream_t *stream_tx = &p_vendor->tx.stream;
+        tu_edpt_stream_t *stream_tx = &p_vendor->stream.tx;
         if (stream_tx->ep_addr == 0) {
           tu_edpt_stream_open(stream_tx, desc_ep);
           tu_edpt_stream_write_xfer(rhport, stream_tx); // flush pending data
         }
       } else {
-        tu_edpt_stream_t *stream_rx = &p_vendor->rx.stream;
+        tu_edpt_stream_t *stream_rx = &p_vendor->stream.rx;
         if (stream_rx->ep_addr == 0) {
           tu_edpt_stream_open(stream_rx, desc_ep);
           TU_ASSERT(tu_edpt_stream_read_xfer(rhport, stream_rx) > 0, 0); // prepare for incoming data
@@ -247,38 +261,30 @@ uint16_t vendord_open(uint8_t rhport, const tusb_desc_interface_t* desc_itf, uin
 
 bool vendord_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes) {
   (void) result;
+  const uint8_t idx = find_vendor_itf(ep_addr);
+  TU_VERIFY(idx < CFG_TUD_VENDOR);
+  vendord_interface_t *p_vendor = &_vendord_itf[idx];
+  vendord_epbuf_t     *p_epbuf  = &_vendord_epbuf[idx];
 
-  uint8_t itf;
-  vendord_interface_t* p_vendor;
-
-  for (itf = 0; itf < CFG_TUD_VENDOR; itf++) {
-    p_vendor = &_vendord_itf[itf];
-    if ((ep_addr == p_vendor->rx.stream.ep_addr) || (ep_addr == p_vendor->tx.stream.ep_addr)) {
-      break;
-    }
-  }
-  TU_VERIFY(itf < CFG_TUD_VENDOR);
-  vendord_epbuf_t* p_epbuf = &_vendord_epbuf[itf];
-
-  if ( ep_addr == p_vendor->rx.stream.ep_addr ) {
+  if (ep_addr == p_vendor->stream.rx.ep_addr) {
     // Received new data: put into stream's fifo
-    tu_edpt_stream_read_xfer_complete(&p_vendor->rx.stream, xferred_bytes);
+    tu_edpt_stream_read_xfer_complete(&p_vendor->stream.rx, xferred_bytes);
 
     // Invoked callback if any
-    tud_vendor_rx_cb(itf, p_epbuf->epout, (uint16_t) xferred_bytes);
+    tud_vendor_rx_cb(idx, p_epbuf->epout, (uint16_t)xferred_bytes);
 
-    tu_edpt_stream_read_xfer(rhport, &p_vendor->rx.stream);
-  } else if ( ep_addr == p_vendor->tx.stream.ep_addr ) {
+    tu_edpt_stream_read_xfer(rhport, &p_vendor->stream.rx);
+  } else if (ep_addr == p_vendor->stream.tx.ep_addr) {
     // Send complete
-    tud_vendor_tx_cb(itf, (uint16_t) xferred_bytes);
+    tud_vendor_tx_cb(idx, (uint16_t)xferred_bytes);
 
-    #if CFG_TUD_VENDOR_TX_BUFSIZE > 0
+  #if CFG_TUD_VENDOR_TX_BUFSIZE > 0
     // try to send more if possible
-    if ( 0 == tu_edpt_stream_write_xfer(rhport, &p_vendor->tx.stream) ) {
+    if (0 == tu_edpt_stream_write_xfer(rhport, &p_vendor->stream.tx)) {
       // If there is no data left, a ZLP should be sent if xferred_bytes is multiple of EP Packet size and not zero
-      tu_edpt_stream_write_zlp_if_needed(rhport, &p_vendor->tx.stream, xferred_bytes);
+      tu_edpt_stream_write_zlp_if_needed(rhport, &p_vendor->stream.tx, xferred_bytes);
     }
-    #endif
+  #endif
   }
 
   return true;
diff --git a/src/class/vendor/vendor_device.h b/src/class/vendor/vendor_device.h
index 5376f3917..e9dec788b 100644
--- a/src/class/vendor/vendor_device.h
+++ b/src/class/vendor/vendor_device.h
@@ -30,84 +30,87 @@
 #include "common/tusb_common.h"
 
 #ifndef CFG_TUD_VENDOR_EPSIZE
-#define CFG_TUD_VENDOR_EPSIZE     64
+  #define CFG_TUD_VENDOR_EPSIZE 64
 #endif
 
 // RX FIFO can be disabled by setting this value to 0
 #ifndef CFG_TUD_VENDOR_RX_BUFSIZE
-#define CFG_TUD_VENDOR_RX_BUFSIZE    64
+  #define CFG_TUD_VENDOR_RX_BUFSIZE 64
 #endif
 
 // TX FIFO can be disabled by setting this value to 0
 #ifndef CFG_TUD_VENDOR_TX_BUFSIZE
-#define CFG_TUD_VENDOR_TX_BUFSIZE    64
+  #define CFG_TUD_VENDOR_TX_BUFSIZE 64
 #endif
 
 #ifdef __cplusplus
- extern "C" {
+extern "C" {
 #endif
 
 //--------------------------------------------------------------------+
 // Application API (Multiple Interfaces) i.e CFG_TUD_VENDOR > 1
 //--------------------------------------------------------------------+
-bool     tud_vendor_n_mounted         (uint8_t itf);
-uint32_t tud_vendor_n_available       (uint8_t itf);
-uint32_t tud_vendor_n_read            (uint8_t itf, void* buffer, uint32_t bufsize);
-bool     tud_vendor_n_peek            (uint8_t itf, uint8_t* ui8);
-void     tud_vendor_n_read_flush      (uint8_t itf);
+bool     tud_vendor_n_mounted(uint8_t idx);
+uint32_t tud_vendor_n_available(uint8_t idx);
+bool     tud_vendor_n_peek(uint8_t idx, uint8_t *ui8);
 
-uint32_t tud_vendor_n_write           (uint8_t itf, void const* buffer, uint32_t bufsize);
-uint32_t tud_vendor_n_write_flush     (uint8_t itf);
-uint32_t tud_vendor_n_write_available (uint8_t itf);
+uint32_t tud_vendor_n_read(uint8_t idx, void *buffer, uint32_t bufsize);
+uint32_t tud_vendor_n_read_discard(uint8_t idx, uint32_t count);
+void     tud_vendor_n_read_flush(uint8_t idx);
 
-TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_n_write_str (uint8_t itf, char const* str);
+uint32_t tud_vendor_n_write(uint8_t idx, const void *buffer, uint32_t bufsize);
+uint32_t tud_vendor_n_write_flush(uint8_t idx);
+uint32_t tud_vendor_n_write_available(uint8_t idx);
+
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_n_write_str(uint8_t idx, const char *str) {
+  return tud_vendor_n_write(idx, str, strlen(str));
+}
 
 // backward compatible
-#define tud_vendor_n_flush(itf) tud_vendor_n_write_flush(itf)
+#define tud_vendor_n_flush(idx) tud_vendor_n_write_flush(idx)
 
 //--------------------------------------------------------------------+
 // Application API (Single Port) i.e CFG_TUD_VENDOR = 1
 //--------------------------------------------------------------------+
-
-TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_n_write_str(uint8_t itf, char const* str) {
- return tud_vendor_n_write(itf, str, strlen(str));
-}
-
 TU_ATTR_ALWAYS_INLINE static inline bool tud_vendor_mounted(void) {
- return tud_vendor_n_mounted(0);
+  return tud_vendor_n_mounted(0);
 }
 
 TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_available(void) {
- return tud_vendor_n_available(0);
+  return tud_vendor_n_available(0);
 }
 
-TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_read(void* buffer, uint32_t bufsize) {
- return tud_vendor_n_read(0, buffer, bufsize);
+TU_ATTR_ALWAYS_INLINE static inline bool tud_vendor_peek(uint8_t *ui8) {
+  return tud_vendor_n_peek(0, ui8);
 }
 
-TU_ATTR_ALWAYS_INLINE static inline bool tud_vendor_peek(uint8_t* ui8) {
- return tud_vendor_n_peek(0, ui8);
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_read(void *buffer, uint32_t bufsize) {
+  return tud_vendor_n_read(0, buffer, bufsize);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_read_discard(uint32_t count) {
+  return tud_vendor_n_read_discard(0, count);
 }
 
 TU_ATTR_ALWAYS_INLINE static inline void tud_vendor_read_flush(void) {
- tud_vendor_n_read_flush(0);
+  tud_vendor_n_read_flush(0);
 }
 
-TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_write(void const* buffer, uint32_t bufsize) {
- return tud_vendor_n_write(0, buffer, bufsize);
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_write(const void *buffer, uint32_t bufsize) {
+  return tud_vendor_n_write(0, buffer, bufsize);
 }
 
-TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_write_str(char const* str) {
- return tud_vendor_n_write_str(0, str);
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_write_str(const char *str) {
+  return tud_vendor_n_write_str(0, str);
 }
 
 TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_write_flush(void) {
- return tud_vendor_n_write_flush(0);
+  return tud_vendor_n_write_flush(0);
 }
 
 #if CFG_TUD_VENDOR_TX_BUFSIZE > 0
 TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_write_available(void) {
- return tud_vendor_n_write_available(0);
+  return tud_vendor_n_write_available(0);
 }
 #endif
 
@@ -119,9 +122,9 @@ TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_write_available(void) {
 //--------------------------------------------------------------------+
 
 // Invoked when received new data
-void tud_vendor_rx_cb(uint8_t itf, uint8_t const* buffer, uint16_t bufsize);
+void tud_vendor_rx_cb(uint8_t idx, const uint8_t *buffer, uint16_t bufsize);
 // Invoked when last rx transfer finished
-void tud_vendor_tx_cb(uint8_t itf, uint32_t sent_bytes);
+void tud_vendor_tx_cb(uint8_t idx, uint32_t sent_bytes);
 
 //--------------------------------------------------------------------+
 // Inline Functions
@@ -134,11 +137,11 @@ void tud_vendor_tx_cb(uint8_t itf, uint32_t sent_bytes);
 void     vendord_init(void);
 bool     vendord_deinit(void);
 void     vendord_reset(uint8_t rhport);
-uint16_t vendord_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uint16_t max_len);
+uint16_t vendord_open(uint8_t rhport, const tusb_desc_interface_t *idx_desc, uint16_t max_len);
 bool     vendord_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes);
 
 #ifdef __cplusplus
- }
+}
 #endif
 
 #endif /* TUSB_VENDOR_DEVICE_H_ */