diff --git a/firmware/hackrf_usb/CMakeLists.txt b/firmware/hackrf_usb/CMakeLists.txt
index 10ee4ffb..8db83f7f 100644
--- a/firmware/hackrf_usb/CMakeLists.txt
+++ b/firmware/hackrf_usb/CMakeLists.txt
@@ -42,6 +42,7 @@ set(SRC_M4
 	usb_api_register.c
 	usb_api_spiflash.c
 	usb_api_transceiver.c
+	usb_api_scan.c
 	"${PATH_HACKRF_FIRMWARE_COMMON}/usb_queue.c"
 	"${PATH_HACKRF_FIRMWARE_COMMON}/fault_handler.c"
 	"${PATH_HACKRF_FIRMWARE_COMMON}/cpld_jtag.c"
diff --git a/firmware/hackrf_usb/hackrf_usb.c b/firmware/hackrf_usb/hackrf_usb.c
index 394875c4..c5dea94c 100644
--- a/firmware/hackrf_usb/hackrf_usb.c
+++ b/firmware/hackrf_usb/hackrf_usb.c
@@ -42,6 +42,7 @@
 #include "usb_api_cpld.h"
 #include "usb_api_register.h"
 #include "usb_api_spiflash.h"
+#include "usb_api_scan.h"
 
 #include "usb_api_transceiver.h"
 #include "sgpio_isr.h"
@@ -142,6 +143,7 @@ static const usb_request_handler_fn vendor_request_handler[] = {
 #endif
 	usb_vendor_request_set_freq_explicit,
 	usb_vendor_request_read_wcid,  // USB_WCID_VENDOR_REQ
+	usb_vendor_request_init_scan,
 };
 
 static const uint32_t vendor_request_handler_count =
@@ -241,13 +243,8 @@ int main(void) {
 	rf_path_init(&rf_path);
 
 	unsigned int phase = 0;
-
 	unsigned int blocks_queued = 0;
-	const uint64_t scan_freq_min = 100000000;
-	const uint64_t scan_freq_max = 6000000000;
-	const uint64_t scan_freq_step = 20000000;
-	uint64_t scan_freq = scan_freq_min;
-	set_freq(scan_freq);
+
 	while(true) {
 		// Check whether we need to initiate a CPLD update
 		if (start_cpld_update)
@@ -286,11 +283,7 @@ int main(void) {
 		}
 
 		if (blocks_queued > 2) {
-			scan_freq += scan_freq_step;
-			if (scan_freq > scan_freq_max) {
-				scan_freq = scan_freq_min;
-			}
-			set_freq(scan_freq);
+			scan_callback();
 			blocks_queued = 0;
 		}
 	}
diff --git a/firmware/hackrf_usb/usb_api_scan.c b/firmware/hackrf_usb/usb_api_scan.c
new file mode 100644
index 00000000..376a17f7
--- /dev/null
+++ b/firmware/hackrf_usb/usb_api_scan.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2016 Mike Walters, Dominic Spill
+ *
+ * This file is part of HackRF.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "usb_api_scan.h"
+#include "usb_queue.h"
+#include <stddef.h>
+//#include <hackrf_core.h>
+#include "tuning.h"
+
+volatile bool scan_mode = false;
+static uint64_t scan_freq;
+static uint64_t scan_freq_min;
+static uint64_t scan_freq_max;
+static uint64_t scan_freq_step;
+
+usb_request_status_t usb_vendor_request_init_scan(
+		usb_endpoint_t* const endpoint, const usb_transfer_stage_t stage)
+{
+	if (stage == USB_TRANSFER_STAGE_SETUP) {
+		// DGS set scan frequencies here
+		scan_freq = scan_freq_min;
+		set_freq(scan_freq);
+		scan_mode = true;
+		usb_transfer_schedule_ack(endpoint->in);
+	}
+	return USB_REQUEST_STATUS_OK;
+}
+
+void scan_callback(void) {
+	scan_freq += scan_freq_step;
+	if (scan_freq > scan_freq_max) {
+		scan_freq = scan_freq_min;
+		}
+		set_freq(scan_freq);
+}
diff --git a/firmware/hackrf_usb/usb_api_scan.h b/firmware/hackrf_usb/usb_api_scan.h
new file mode 100644
index 00000000..3aca5372
--- /dev/null
+++ b/firmware/hackrf_usb/usb_api_scan.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2016 Mike Walters, Dominic Spill
+ *
+ * This file is part of HackRF.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __USB_API_SCAN_H__
+#define __USB_API_SCAN_H__
+
+#include <stdbool.h>
+#include <usb_type.h>
+#include <usb_request.h>
+
+extern volatile bool scan_mode;
+
+usb_request_status_t usb_vendor_request_init_scan(
+	usb_endpoint_t* const endpoint, const usb_transfer_stage_t stage);
+
+void scan_callback(void);
+
+#endif /* __USB_API_SPCAN_H__ */