diff --git a/firmware/ice40-riscv/e1-tracer/usb_e1.c b/firmware/ice40-riscv/e1-tracer/usb_e1.c
new file mode 100644
index 0000000..421305b
--- /dev/null
+++ b/firmware/ice40-riscv/e1-tracer/usb_e1.c
@@ -0,0 +1,230 @@
+/*
+ * usb_e1.c
+ *
+ * Copyright (C) 2019-2020  Sylvain Munaut <tnt@246tNt.com>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+
+#include <no2usb/usb_hw.h>
+#include <no2usb/usb_priv.h>
+
+#include "console.h"
+#include "e1.h"
+#include "misc.h"
+
+struct {
+	bool running;
+	int in_bdi[2];
+} g_usb_e1;
+
+
+/* Hack */
+unsigned int e1_rx_need_data(int chan, unsigned int usb_addr, unsigned int max_len, unsigned int *pos);
+unsigned int e1_rx_level(int chan);
+uint8_t e1_get_pending_flags(int chan);
+/* ---- */
+
+bool
+usb_ep_boot(const struct usb_intf_desc *intf, uint8_t ep_addr, bool dual_bd);
+
+
+void
+usb_e1_run(void)
+{
+	int chan;
+	int bdi;
+
+	if (!g_usb_e1.running)
+		return;
+
+	/* EP[1-2] IN */
+	for (chan=0; chan<2; chan++)
+	{
+		bdi = g_usb_e1.in_bdi[chan];
+
+		while ((usb_ep_regs[1+chan].in.bd[bdi].csr & USB_BD_STATE_MSK) != USB_BD_STATE_RDY_DATA)
+		{
+			uint32_t ptr = usb_ep_regs[1+chan].in.bd[bdi].ptr;
+			uint32_t hdr;
+			unsigned int pos;
+
+			/* Error check */
+			if ((usb_ep_regs[1+chan].in.bd[bdi].csr & USB_BD_STATE_MSK) == USB_BD_STATE_DONE_ERR)
+				printf("Err EP%d IN\n", 1+chan);
+
+			/* Get some data from E1 */
+			int n = e1_rx_level(chan);
+
+//			if (n > 64)
+//				n = 12;
+//			else if (n > 32)
+//				n = 10;
+//			else if (n > 8)
+//				n = 8;
+			if (n > 12)
+				n = 12;
+			else if (!n)
+				break;
+
+			n = e1_rx_need_data(chan, (ptr >> 2) + 1, n, &pos);
+
+			/* Write header */
+				/* [31:12] (reserved) */
+				/* [11:10] CRC results (first new multiframe present in packet)  */
+				/* [ 9: 8] CRC results (second new multiframe present in packet) */
+				/* [ 7: 5] Multiframe sequence number (first frame of packet)    */
+				/* [ 4: 0] Position in multi-frame    (first frame of packet)    */
+			hdr = (pos & 0xff) | (e1_get_pending_flags(chan) << 24);
+			usb_data_write(ptr, &hdr, 4);
+			usb_ep_regs[1+chan].in.bd[bdi].csr = USB_BD_STATE_RDY_DATA | USB_BD_LEN((n * 32) + 4);
+
+			/* Next BDI */
+			bdi ^= 1;
+			g_usb_e1.in_bdi[chan] = bdi;
+		}
+	}
+}
+
+static const struct usb_intf_desc *
+_find_intf(const struct usb_conf_desc *conf, uint8_t idx)
+{
+	const struct usb_intf_desc *intf = NULL;
+	const void *sod, *eod;
+
+	if (!conf)
+		return NULL;
+
+	sod = conf;
+	eod = sod + conf->wTotalLength;
+
+	while (1) {
+		sod = usb_desc_find(sod, eod, USB_DT_INTF);
+		if (!sod)
+			break;
+
+		intf = (void*)sod;
+		if (intf->bInterfaceNumber == idx)
+			return intf;
+
+		sod = usb_desc_next(sod);
+	}
+
+	return NULL;
+}
+enum usb_fnd_resp
+_e1_set_conf(const struct usb_conf_desc *conf)
+{
+	const struct usb_intf_desc *intf;
+
+	printf("e1 set_conf %08x\n", conf);
+	if (!conf)
+		return USB_FND_SUCCESS;
+
+	intf = _find_intf(conf, 0);
+	if (!intf)
+		return USB_FND_ERROR;
+
+	printf("e1 set_conf %08x\n", intf);
+
+	usb_ep_boot(intf, 0x81, true);
+	usb_ep_boot(intf, 0x82, true);
+
+	return USB_FND_SUCCESS;
+}
+
+enum usb_fnd_resp
+_e1_set_intf(const struct usb_intf_desc *base, const struct usb_intf_desc *sel)
+{
+	if (base->bInterfaceNumber != 0)
+		return USB_FND_CONTINUE;
+
+	if (sel->bAlternateSetting == 0)
+	{
+		/* Already stopped ? */
+		if (!g_usb_e1.running)
+			return USB_FND_SUCCESS;
+
+		/* Update state */
+		g_usb_e1.running = false;
+
+		/* Stop E1 */
+		e1_stop();
+
+		/* Disable end-points */
+		usb_ep_regs[1].in.status = 0;
+		usb_ep_regs[2].in.status = 0;
+	}
+	else if (sel->bAlternateSetting == 1)
+	{
+		/* Already running ? */
+		if (g_usb_e1.running)
+			return USB_FND_SUCCESS;
+
+		/* Update state */
+		g_usb_e1.running = true;
+
+		/* Reset buffer pointers */
+		g_usb_e1.in_bdi[0] = 0;
+		g_usb_e1.in_bdi[1] = 0;
+
+		/* Configure EP1 IN / EP2 IN */
+		usb_ep_regs[1].in.status = USB_EP_TYPE_ISOC | USB_EP_BD_DUAL;	/* Type=Isochronous, dual buffered */
+		usb_ep_regs[2].in.status = USB_EP_TYPE_ISOC | USB_EP_BD_DUAL;	/* Type=Isochronous, dual buffered */
+
+		/* EP1 IN: Prepare two buffers */
+		usb_ep_regs[1].in.bd[0].ptr = 256 + 0 * 388;
+		usb_ep_regs[1].in.bd[0].csr = 0;
+
+		usb_ep_regs[1].in.bd[1].ptr = 256 + 1 * 388;
+		usb_ep_regs[1].in.bd[1].csr = 0;
+
+		/* EP2 IN: Prepare two buffers */
+		usb_ep_regs[2].in.bd[0].ptr = 256 + 2 * 388;
+		usb_ep_regs[2].in.bd[0].csr = 0;
+
+		usb_ep_regs[2].in.bd[1].ptr = 256 + 3 * 388;
+		usb_ep_regs[2].in.bd[1].csr = 0;
+
+		/* Start E1 */
+		e1_start();
+	}
+	else
+	{
+		/* Unknown */
+		return USB_FND_ERROR;
+	}
+
+
+	return USB_FND_SUCCESS;
+}
+
+enum usb_fnd_resp
+_e1_get_intf(const struct usb_intf_desc *base, uint8_t *alt)
+{
+	if (base->bInterfaceNumber != 0)
+		return USB_FND_CONTINUE;
+
+	*alt = g_usb_e1.running ? 1 : 0;
+
+	return USB_FND_SUCCESS;
+}
+
+static struct usb_fn_drv _e1_drv = {
+	.set_conf	= _e1_set_conf,
+        .set_intf       = _e1_set_intf,
+        .get_intf       = _e1_get_intf,
+};
+
+void
+usb_e1_init(void)
+{
+	/* Clear state */
+	memset(&g_usb_e1, 0x00, sizeof(g_usb_e1));
+
+	/* Install driver */
+	usb_register_function_driver(&_e1_drv);
+}