diff --git a/src/stm32/usbfs.c b/src/stm32/usbfs.c
index 2e1bc420d..3751a4f5a 100644
--- a/src/stm32/usbfs.c
+++ b/src/stm32/usbfs.c
@@ -242,8 +242,9 @@ usb_read_bulk_out(void *data, uint_fast8_t max_len)
 static uint32_t bulk_in_push_pos, bulk_in_pop_flag;
 #define BI_START 2
 
-int_fast8_t
-usb_send_bulk_in(void *data, uint_fast8_t len)
+// Send bulk packet to host with double buffering optimization
+static int_fast8_t
+usb_send_bulk_in_double_buffer(void *data, uint_fast8_t len)
 {
     if (readl(&bulk_in_pop_flag))
         // No buffer space available
@@ -275,6 +276,21 @@ usb_send_bulk_in(void *data, uint_fast8_t len)
     return len;
 }
 
+// Send bulk usb packet to host
+int_fast8_t
+usb_send_bulk_in(void *data, uint_fast8_t len)
+{
+    if (CONFIG_STM32_USB_DOUBLE_BUFFER_TX)
+        return usb_send_bulk_in_double_buffer(data, len);
+    uint32_t ep = USB_CDC_EP_BULK_IN, epr = USB_EPR[ep];
+    if ((epr & USB_EPTX_STAT) != USB_EP_TX_NAK)
+        // No buffer space available
+        return -1;
+    btable_write_packet(ep, BUFTX, data, len);
+    USB_EPR[ep] = calc_epr_bits(epr, USB_EPTX_STAT, USB_EP_TX_VALID);
+    return len;
+}
+
 int_fast8_t
 usb_read_ep0(void *data, uint_fast8_t max_len)
 {
@@ -333,9 +349,10 @@ usb_set_configure(void)
     bulk_out_pop_count = 0;
     USB_EPR[ep] = calc_epr_bits(USB_EPR[ep], USB_EPRX_STAT, USB_EP_RX_VALID);
 
-    ep = USB_CDC_EP_BULK_IN;
-    bulk_in_push_pos = BI_START;
-    writel(&bulk_in_pop_flag, 0);
+    if (CONFIG_STM32_USB_DOUBLE_BUFFER_TX) {
+        bulk_in_push_pos = BI_START;
+        writel(&bulk_in_pop_flag, 0);
+    }
 }
 
 
@@ -360,9 +377,12 @@ usb_reset(void)
     bulk_out_push_flag = USB_EP_DTOG_TX;
 
     ep = USB_CDC_EP_BULK_IN;
-    USB_EPR[ep] = (USB_CDC_EP_BULK_IN | USB_EP_BULK | USB_EP_KIND
-                   | USB_EP_TX_NAK);
-    bulk_in_pop_flag = USB_EP_DTOG_RX;
+    uint32_t bi_epr_flags = USB_CDC_EP_BULK_IN | USB_EP_BULK | USB_EP_TX_NAK;
+    if (CONFIG_STM32_USB_DOUBLE_BUFFER_TX) {
+        bi_epr_flags |= USB_EP_KIND;
+        bulk_in_pop_flag = USB_EP_DTOG_RX;
+    }
+    USB_EPR[ep] = bi_epr_flags;
 
     USB->CNTR = USB_CNTR_CTRM | USB_CNTR_RESETM;
     USB->DADDR = USB_DADDR_EF;
@@ -382,9 +402,12 @@ USB_IRQHandler(void)
             bulk_out_push_flag = 0;
             usb_notify_bulk_out();
         } else if (ep == USB_CDC_EP_BULK_IN) {
-            USB_EPR[ep] = (calc_epr_bits(epr, USB_EP_CTR_RX | USB_EP_CTR_TX, 0)
-                           | bulk_in_pop_flag);
-            bulk_in_pop_flag = 0;
+            uint32_t ne = calc_epr_bits(epr, USB_EP_CTR_RX | USB_EP_CTR_TX, 0);
+            if (CONFIG_STM32_USB_DOUBLE_BUFFER_TX) {
+                ne |= bulk_in_pop_flag;
+                bulk_in_pop_flag = 0;
+            }
+            USB_EPR[ep] = ne;
             usb_notify_bulk_in();
         } else if (ep == 0) {
             USB_EPR[ep] = calc_epr_bits(epr, USB_EP_CTR_RX | USB_EP_CTR_TX, 0);