diff --git a/firmware/ice40-riscv/e1-tracer/usb_desc_app.c b/firmware/ice40-riscv/e1-tracer/usb_desc_app.c
new file mode 100644
index 0000000..176ec12
--- /dev/null
+++ b/firmware/ice40-riscv/e1-tracer/usb_desc_app.c
@@ -0,0 +1,253 @@
+/*
+ * usb_desc_app.c
+ *
+ * Copyright (C) 2019-2020  Sylvain Munaut <tnt@246tNt.com>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <no2usb/usb_proto.h>
+#include <no2usb/usb.h>
+
+#define NULL ((void*)0)
+#define num_elem(a) (sizeof(a) / sizeof(a[0]))
+
+
+static const struct {
+	/* Configuration */
+	struct usb_conf_desc conf;
+
+	/* E1 */
+	struct {
+		struct {
+			struct usb_intf_desc intf;
+			struct usb_ep_desc ep_data_in0;
+			struct usb_ep_desc ep_data_in1;
+		} __attribute__ ((packed)) off;
+		struct {
+			struct usb_intf_desc intf;
+			struct usb_ep_desc ep_data_in0;
+			struct usb_ep_desc ep_data_in1;
+		} __attribute__ ((packed)) on;
+	} __attribute__ ((packed)) e1;
+
+	/* CDC */
+#if 0
+	struct {
+		struct usb_intf_desc intf_ctl;
+		struct usb_cs_intf_hdr_desc cs_intf_hdr;
+		struct usb_cs_intf_acm_desc cs_intf_acm;
+		struct usb_cs_intf_union_desc cs_intf_union;
+		uint8_t cs_intf_union_slave;
+		struct usb_ep_desc ep_ctl;
+		struct usb_intf_desc intf_data;
+		struct usb_ep_desc ep_data_out;
+		struct usb_ep_desc ep_data_in;
+	} __attribute__ ((packed)) cdc;
+#endif
+
+	/* DFU Runtime */
+	struct {
+		struct usb_intf_desc intf;
+		struct usb_dfu_desc func;
+	} __attribute__ ((packed)) dfu;
+} __attribute__ ((packed)) _app_conf_desc = {
+	.conf = {
+		.bLength                = sizeof(struct usb_conf_desc),
+		.bDescriptorType        = USB_DT_CONF,
+		.wTotalLength           = sizeof(_app_conf_desc),
+#if 0
+		.bNumInterfaces         = 4,
+#else
+		.bNumInterfaces         = 2,
+#endif
+		.bConfigurationValue    = 1,
+		.iConfiguration         = 4,
+		.bmAttributes           = 0x80,
+		.bMaxPower              = 0x32, /* 100 mA */
+	},
+	.e1 = {
+		.off = {
+			.intf = {
+				.bLength		= sizeof(struct usb_intf_desc),
+				.bDescriptorType	= USB_DT_INTF,
+				.bInterfaceNumber	= 0,
+				.bAlternateSetting	= 0,
+				.bNumEndpoints		= 2,
+				.bInterfaceClass	= 0xff,
+				.bInterfaceSubClass	= 0xe1,
+				.bInterfaceProtocol	= 0x00,
+				.iInterface		= 5,
+			},
+			.ep_data_in0 = {
+				.bLength		= sizeof(struct usb_ep_desc),
+				.bDescriptorType	= USB_DT_EP,
+				.bEndpointAddress	= 0x81,
+				.bmAttributes		= 0x05,
+				.wMaxPacketSize		= 0,
+				.bInterval		= 1,
+			},
+			.ep_data_in1 = {
+				.bLength		= sizeof(struct usb_ep_desc),
+				.bDescriptorType	= USB_DT_EP,
+				.bEndpointAddress	= 0x82,
+				.bmAttributes		= 0x05,
+				.wMaxPacketSize		= 0,
+				.bInterval		= 1,
+			},
+		},
+		.on = {
+			.intf = {
+				.bLength		= sizeof(struct usb_intf_desc),
+				.bDescriptorType	= USB_DT_INTF,
+				.bInterfaceNumber	= 0,
+				.bAlternateSetting	= 1,
+				.bNumEndpoints		= 2,
+				.bInterfaceClass	= 0xff,
+				.bInterfaceSubClass	= 0xe1,
+				.bInterfaceProtocol	= 0x00,
+				.iInterface		= 5,
+			},
+			.ep_data_in0 = {
+				.bLength		= sizeof(struct usb_ep_desc),
+				.bDescriptorType	= USB_DT_EP,
+				.bEndpointAddress	= 0x81,
+				.bmAttributes		= 0x05,
+				.wMaxPacketSize		= 388,
+				.bInterval		= 1,
+			},
+			.ep_data_in1 = {
+				.bLength		= sizeof(struct usb_ep_desc),
+				.bDescriptorType	= USB_DT_EP,
+				.bEndpointAddress	= 0x82,
+				.bmAttributes		= 0x05,
+				.wMaxPacketSize		= 388,
+				.bInterval		= 1,
+			},
+		},
+	},
+#if 0
+	.cdc = {
+		.intf_ctl = {
+			.bLength		= sizeof(struct usb_intf_desc),
+			.bDescriptorType	= USB_DT_INTF,
+			.bInterfaceNumber	= 1,
+			.bAlternateSetting	= 0,
+			.bNumEndpoints		= 1,
+			.bInterfaceClass	= 0x02,
+			.bInterfaceSubClass	= 0x02,
+			.bInterfaceProtocol	= 0x00,
+			.iInterface		= 6,
+		},
+		.cs_intf_hdr = {
+			.bLength		= sizeof(struct usb_cs_intf_hdr_desc),
+			.bDescriptorType	= USB_DT_CS_INTF,
+			.bDescriptorsubtype	= 0x00,
+			.bcdCDC			= 0x0110,
+		},
+		.cs_intf_acm = {
+			.bLength		= sizeof(struct usb_cs_intf_acm_desc),
+			.bDescriptorType	= USB_DT_CS_INTF,
+			.bDescriptorsubtype	= 0x02,
+			.bmCapabilities		= 0x00,
+		},
+		.cs_intf_union = {
+			.bLength		= sizeof(struct usb_cs_intf_union_desc) + 1,
+			.bDescriptorType	= USB_DT_CS_INTF,
+			.bDescriptorsubtype	= 0x06,
+			.bMasterInterface	= 1,
+		},
+		.cs_intf_union_slave = 2,
+		.ep_ctl = {
+			.bLength		= sizeof(struct usb_ep_desc),
+			.bDescriptorType	= USB_DT_EP,
+			.bEndpointAddress	= 0x84,
+			.bmAttributes		= 0x03,
+			.wMaxPacketSize		= 64,
+			.bInterval		= 0xff,
+		},
+		.intf_data = {
+			.bLength		= sizeof(struct usb_intf_desc),
+			.bDescriptorType	= USB_DT_INTF,
+			.bInterfaceNumber	= 2,
+			.bAlternateSetting	= 0,
+			.bNumEndpoints		= 2,
+			.bInterfaceClass	= 0x0a,
+			.bInterfaceSubClass	= 0x00,
+			.bInterfaceProtocol	= 0x00,
+			.iInterface		= 7,
+		},
+		.ep_data_out = {
+			.bLength		= sizeof(struct usb_ep_desc),
+			.bDescriptorType	= USB_DT_EP,
+			.bEndpointAddress	= 0x05,
+			.bmAttributes		= 0x02,
+			.wMaxPacketSize		= 64,
+			.bInterval		= 0x00,
+		},
+		.ep_data_in = {
+			.bLength		= sizeof(struct usb_ep_desc),
+			.bDescriptorType	= USB_DT_EP,
+			.bEndpointAddress	= 0x85,
+			.bmAttributes		= 0x02,
+			.wMaxPacketSize		= 64,
+			.bInterval		= 0x01,
+		},
+	},
+#endif
+	.dfu = {
+		.intf = {
+			.bLength		= sizeof(struct usb_intf_desc),
+			.bDescriptorType	= USB_DT_INTF,
+#if 0
+			.bInterfaceNumber	= 3,
+#else
+			.bInterfaceNumber	= 1,
+#endif
+			.bAlternateSetting	= 0,
+			.bNumEndpoints		= 0,
+			.bInterfaceClass	= 0xfe,
+			.bInterfaceSubClass	= 0x01,
+			.bInterfaceProtocol	= 0x01,
+			.iInterface		= 8,
+		},
+		.func = {
+			.bLength		= sizeof(struct usb_dfu_desc),
+			.bDescriptorType	= USB_DT_DFU,
+			.bmAttributes		= 0x0d,
+			.wDetachTimeOut		= 1000,
+			.wTransferSize		= 4096,
+			.bcdDFUVersion		= 0x0101,
+		},
+	},
+};
+
+static const struct usb_conf_desc * const _conf_desc_array[] = {
+	&_app_conf_desc.conf,
+};
+
+static const struct usb_dev_desc _dev_desc = {
+	.bLength		= sizeof(struct usb_dev_desc),
+	.bDescriptorType	= USB_DT_DEV,
+	.bcdUSB			= 0x0200,
+	.bDeviceClass		= 0,
+	.bDeviceSubClass	= 0,
+	.bDeviceProtocol	= 0,
+	.bMaxPacketSize0	= 64,
+	.idVendor		= 0x1d50,
+	.idProduct		= 0x6151,
+	.bcdDevice		= 2,
+	.iManufacturer		= 2,
+	.iProduct		= 3,
+	.iSerialNumber		= 1,
+	.bNumConfigurations	= num_elem(_conf_desc_array),
+};
+
+#include "usb_str_app.gen.h"
+
+const struct usb_stack_descriptors app_stack_desc = {
+	.dev = &_dev_desc,
+	.conf = _conf_desc_array,
+	.n_conf = num_elem(_conf_desc_array),
+	.str = _str_desc_array,
+	.n_str = num_elem(_str_desc_array),
+};