diff --git a/firmware/common/hackrf_core.c b/firmware/common/hackrf_core.c
index 700e19f5..d1be02e7 100644
--- a/firmware/common/hackrf_core.c
+++ b/firmware/common/hackrf_core.c
@@ -39,6 +39,69 @@ void delay(uint32_t duration)
 		__asm__("nop");
 }
 
+bool set_fracrate(const float freq) {
+
+	uint32_t MSx_P1,MSx_P2,MSx_P3;
+	uint32_t b,c;
+	float div = (800/freq);
+	uint32_t a = (uint32_t)div;
+	float x = div-a;
+
+	if(a != div){
+		uint32_t j=0,k=1,l=1,m=1;
+		while (k <= 0xFFFF && m <= 0xFFFF){
+			float n = (float)(j+l)/(k+m);
+			if( x == n){
+				if(k + m <= 0xFFFF){
+					b=j+l;	c=k+m;
+					break;
+				} else if(m > k){
+					b=l; c=m;
+					break;
+				} else {
+					b=j; c=k;
+					break;
+				}
+			}
+			else if(x > n){
+				j+=l; k+=m;
+			}
+			else{
+				l+=j; m+=k;
+			}
+		}
+		if (k > 0xFFFF){
+			b=l; c=m;
+		}
+		else{
+			b=j; c=k;
+		}
+	} else {
+		b=0; c=1;
+	}
+
+	MSx_P1 = 128*a + (128 * b/c) - 512;
+	MSx_P2 = (128*b)%c;
+	MSx_P3 = c;
+
+	
+	/* MS0/CLK0 is the source for the MAX5864/CPLD (CODEC_CLK). */
+	si5351c_configure_multisynth(0, MSx_P1, MSx_P2, MSx_P3, 1);
+
+	/* MS0/CLK1 is the source for the CPLD (CODEC_X2_CLK). */
+	si5351c_configure_multisynth(1, 0, 0, 0, 0);//p1 doesn't matter
+
+	/* MS0/CLK2 is the source for SGPIO (CODEC_X2_CLK) */
+	si5351c_configure_multisynth(2, 0, 0, 0, 0);//p1 doesn't matter
+
+	/* MS0/CLK3 is the source for the external clock output. */
+	//si5351c_configure_multisynth(3, p1, 0, 1, 0); // no clk out
+
+	return true;
+
+}
+
+
 bool sample_rate_set(const uint32_t sample_rate_hz) {
 #ifdef JELLYBEAN
 	/* Due to design issues, Jellybean/Lemondrop frequency plan is limited.
diff --git a/firmware/common/hackrf_core.h b/firmware/common/hackrf_core.h
index 462f8b1d..d32f27e4 100644
--- a/firmware/common/hackrf_core.h
+++ b/firmware/common/hackrf_core.h
@@ -259,6 +259,7 @@ void pin_setup(void);
 
 void enable_1v8_power(void);
 
+bool set_fracrate(const float sampling_rate_mhz);
 bool sample_rate_set(const uint32_t sampling_rate_hz);
 bool baseband_filter_bandwidth_set(const uint32_t bandwidth_hz);
 
diff --git a/firmware/common/si5351c.c b/firmware/common/si5351c.c
index 59b478b3..6cc0d253 100644
--- a/firmware/common/si5351c.c
+++ b/firmware/common/si5351c.c
@@ -230,20 +230,20 @@ void si5351c_configure_clock_control()
 void si5351c_configure_clock_control()
 {
 	uint8_t data[] = {16
-	,SI5351C_CLK_INT_MODE | SI5351C_CLK_PLL_SRC(SI5351C_CLK_PLL_SRC_A) | SI5351C_CLK_SRC(SI5351C_CLK_SRC_MULTISYNTH_SELF) | SI5351C_CLK_IDRV(SI5351C_CLK_IDRV_8MA)
+	,SI5351C_CLK_FRAC_MODE | SI5351C_CLK_PLL_SRC(SI5351C_CLK_PLL_SRC_A) | SI5351C_CLK_SRC(SI5351C_CLK_SRC_MULTISYNTH_SELF) | SI5351C_CLK_IDRV(SI5351C_CLK_IDRV_8MA)
 	,SI5351C_CLK_INT_MODE | SI5351C_CLK_PLL_SRC(SI5351C_CLK_PLL_SRC_A) | SI5351C_CLK_SRC(SI5351C_CLK_SRC_MULTISYNTH_0_4) | SI5351C_CLK_IDRV(SI5351C_CLK_IDRV_8MA)
 	,SI5351C_CLK_INT_MODE | SI5351C_CLK_PLL_SRC(SI5351C_CLK_PLL_SRC_A) | SI5351C_CLK_SRC(SI5351C_CLK_SRC_MULTISYNTH_0_4) | SI5351C_CLK_IDRV(SI5351C_CLK_IDRV_8MA)
 	,SI5351C_CLK_POWERDOWN /*not connected, clock out*/
 	,SI5351C_CLK_INT_MODE | SI5351C_CLK_PLL_SRC(SI5351C_CLK_PLL_SRC_A) | SI5351C_CLK_SRC(SI5351C_CLK_SRC_MULTISYNTH_SELF) | SI5351C_CLK_IDRV(SI5351C_CLK_IDRV_8MA)
 	,SI5351C_CLK_INT_MODE | SI5351C_CLK_PLL_SRC(SI5351C_CLK_PLL_SRC_A) | SI5351C_CLK_SRC(SI5351C_CLK_SRC_MULTISYNTH_SELF) | SI5351C_CLK_IDRV(SI5351C_CLK_IDRV_8MA)
 	,SI5351C_CLK_POWERDOWN | SI5351C_CLK_INT_MODE /*not connected, but: plla int mode*/
-	,SI5351C_CLK_POWERDOWN/* pllb int mode*/| SI5351C_CLK_PLL_SRC(SI5351C_CLK_PLL_SRC_A) | SI5351C_CLK_SRC(SI5351C_CLK_SRC_MULTISYNTH_SELF) | SI5351C_CLK_IDRV(SI5351C_CLK_IDRV_8MA)
+	,SI5351C_CLK_POWERDOWN | SI5351C_CLK_INT_MODE /* pllb int mode*/| SI5351C_CLK_PLL_SRC(SI5351C_CLK_PLL_SRC_B) | SI5351C_CLK_SRC(SI5351C_CLK_SRC_MULTISYNTH_SELF) | SI5351C_CLK_IDRV(SI5351C_CLK_IDRV_8MA)
 	 };
 	si5351c_write(data, sizeof(data));
 }
 #endif
 
-/* Enable CLK outputs 0, 1, 2, 4, 5, 7 only. */
+/* Enable CLK outputs 0, 1, 2, 4, 5, ~7 only. */
  void si5351c_enable_clock_outputs()
  {
 	uint8_t data[] = { 3, 0xC8 };
diff --git a/firmware/common/si5351c.h b/firmware/common/si5351c.h
index ac57a8f9..12f1dc3a 100644
--- a/firmware/common/si5351c.h
+++ b/firmware/common/si5351c.h
@@ -35,6 +35,7 @@ extern "C"
 
 #define SI5351C_CLK_POWERDOWN	(1<<7)
 #define SI5351C_CLK_INT_MODE	(1<<6)
+#define SI5351C_CLK_FRAC_MODE	(0<<6)
 
 #define SI5351C_CLK_PLL_SRC(x)	(x<<5)
 #define SI5351C_CLK_PLL_SRC_A	0
diff --git a/firmware/hackrf_usb/hackrf_usb.c b/firmware/hackrf_usb/hackrf_usb.c
index 83059efa..e42fbb9e 100644
--- a/firmware/hackrf_usb/hackrf_usb.c
+++ b/firmware/hackrf_usb/hackrf_usb.c
@@ -67,6 +67,12 @@ typedef struct {
 
 set_freq_params_t set_freq_params;
 
+typedef struct {
+	float freq_mhz;
+} set_sample_r_params_t;
+
+set_sample_r_params_t set_sample_r_params;
+
 uint8_t switchctrl = 0;
 
 void update_switches(void)
@@ -696,6 +702,28 @@ usb_request_status_t usb_vendor_request_set_freq(
 	}
 }
 
+usb_request_status_t usb_vendor_request_set_fracrate(
+	usb_endpoint_t* const endpoint,
+	const usb_transfer_stage_t stage) 
+{
+	if (stage == USB_TRANSFER_STAGE_SETUP) 
+	{
+		usb_endpoint_schedule(endpoint->out, &set_sample_r_params, sizeof(set_sample_r_params_t));
+		return USB_REQUEST_STATUS_OK;
+	} else if (stage == USB_TRANSFER_STAGE_DATA) 
+	{
+		if( set_fracrate(set_sample_r_params.freq_mhz*2) ) 
+		{
+			usb_endpoint_schedule_ack(endpoint->in);
+			return USB_REQUEST_STATUS_OK;
+		}
+		return USB_REQUEST_STATUS_STALL;
+	} else
+	{
+		return USB_REQUEST_STATUS_OK;
+	}
+}
+
 usb_request_status_t usb_vendor_request_set_amp_enable(
 	usb_endpoint_t* const endpoint, const usb_transfer_stage_t stage)
 {
@@ -821,7 +849,8 @@ static const usb_request_handler_fn vendor_request_handler[] = {
 	usb_vendor_request_read_partid_serialno,
 	usb_vendor_request_set_lna_gain,
 	usb_vendor_request_set_vga_gain,
-	usb_vendor_request_set_txvga_gain
+	usb_vendor_request_set_txvga_gain,
+	usb_vendor_request_set_fracrate
 };
 
 static const uint32_t vendor_request_handler_count =
diff --git a/host/libhackrf/CMakeLists.txt b/host/libhackrf/CMakeLists.txt
index 649d861c..9e376720 100644
--- a/host/libhackrf/CMakeLists.txt
+++ b/host/libhackrf/CMakeLists.txt
@@ -31,10 +31,16 @@ set(VERSION ${VERSION_STRING})
 set(CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/../cmake/modules)
 
 if(MSVC)
-set(THREADS_USE_PTHREADS_WIN32 true)
+	set(THREADS_USE_PTHREADS_WIN32 true)
 else()
-add_definitions(-Wall)
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu90")
+	add_definitions(-Wall)
+	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu90")
+
+	INCLUDE(TestBigEndian)
+	TEST_BIG_ENDIAN(BIGENDIAN)
+	if(${BIGENDIAN})
+		 add_definitions(-DBIG_ENDIAN)
+	endif(${BIGENDIAN})
 endif()
 find_package(USB1 REQUIRED)
 find_package(Threads REQUIRED)
diff --git a/host/libhackrf/src/hackrf.c b/host/libhackrf/src/hackrf.c
index 67c2d97b..e31fb714 100644
--- a/host/libhackrf/src/hackrf.c
+++ b/host/libhackrf/src/hackrf.c
@@ -33,6 +33,13 @@ typedef int bool;
 #define true 1
 #define false 0
 #endif
+
+#ifdef BIG_ENDIAN
+#define TO_LE(x) __builtin_bswap32(x)
+#else
+#define TO_LE(x) x
+#endif
+
 // TODO: Factor this into a shared #include so that firmware can use
 // the same values.
 typedef enum {
@@ -57,6 +64,7 @@ typedef enum {
 	HACKRF_VENDOR_REQUEST_SET_LNA_GAIN = 19,
 	HACKRF_VENDOR_REQUEST_SET_VGA_GAIN = 20,
 	HACKRF_VENDOR_REQUEST_SET_TXVGA_GAIN = 21,
+	HACKRF_VENDOR_REQUEST_SET_FRACRATE = 22,
 } hackrf_vendor_request;
 
 typedef enum {
@@ -731,8 +739,8 @@ int ADDCALL hackrf_set_freq(hackrf_device* device, const uint64_t freq_hz)
 	/* Convert Freq Hz 64bits to Freq MHz (32bits) & Freq Hz (32bits) */
 	l_freq_mhz = (uint32_t)(freq_hz / FREQ_ONE_MHZ);
 	l_freq_hz = (uint32_t)(freq_hz - (((uint64_t)l_freq_mhz) * FREQ_ONE_MHZ));
-	set_freq_params.freq_mhz = l_freq_mhz;
-	set_freq_params.freq_hz = l_freq_hz;
+	set_freq_params.freq_mhz = TO_LE(l_freq_mhz);
+	set_freq_params.freq_hz = TO_LE(l_freq_hz);
 	length = sizeof(set_freq_params_t);
 
 	result = libusb_control_transfer(
@@ -754,6 +762,42 @@ int ADDCALL hackrf_set_freq(hackrf_device* device, const uint64_t freq_hz)
 	}
 }
 
+
+typedef struct {
+	float freq_mhz;
+} set_fracrate_params_t;
+
+
+int ADDCALL hackrf_set_fracrate(hackrf_device* device, const float freq_mhz)
+{
+	uint32_t l_freq_mhz;
+	uint32_t l_freq_hz;
+	set_fracrate_params_t set_fracrate_params;
+	uint8_t length;
+	int result;
+	
+	set_fracrate_params.freq_mhz = TO_LE(freq_mhz);
+	length = sizeof(set_fracrate_params_t);
+
+	result = libusb_control_transfer(
+		device->usb_device,
+		LIBUSB_ENDPOINT_OUT | LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_RECIPIENT_DEVICE,
+		HACKRF_VENDOR_REQUEST_SET_FRACRATE,
+		0,
+		0,
+		(unsigned char*)&set_fracrate_params,
+		length,
+		0
+	);
+
+	if (result < length)
+	{
+		return HACKRF_ERROR_LIBUSB;
+	} else {
+		return HACKRF_SUCCESS;
+	}
+}
+
 int ADDCALL hackrf_set_amp_enable(hackrf_device* device, const uint8_t value)
 {
 	int result;
@@ -797,6 +841,14 @@ int ADDCALL hackrf_board_partid_serialno_read(hackrf_device* device, read_partid
 	{
 		return HACKRF_ERROR_LIBUSB;
 	} else {
+
+		read_partid_serialno->part_id[0] = TO_LE(read_partid_serialno->part_id[0]);
+		read_partid_serialno->part_id[0] = TO_LE(read_partid_serialno->part_id[1]);
+		read_partid_serialno->serial_no[0] = TO_LE(read_partid_serialno->serial_no[0]);
+		read_partid_serialno->serial_no[1] = TO_LE(read_partid_serialno->serial_no[1]);
+		read_partid_serialno->serial_no[2] = TO_LE(read_partid_serialno->serial_no[2]);
+		read_partid_serialno->serial_no[3] = TO_LE(read_partid_serialno->serial_no[3]);
+
 		return HACKRF_SUCCESS;
 	}
 }
@@ -804,6 +856,7 @@ int ADDCALL hackrf_board_partid_serialno_read(hackrf_device* device, read_partid
 int ADDCALL hackrf_set_lna_gain(hackrf_device* device, uint32_t value)
 {
 	int result;
+	uint8_t retval;
 	
 	if( value > 40 )
 	{
@@ -812,16 +865,16 @@ int ADDCALL hackrf_set_lna_gain(hackrf_device* device, uint32_t value)
 
 	result = libusb_control_transfer(
 		device->usb_device,
-		LIBUSB_ENDPOINT_OUT | LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_RECIPIENT_DEVICE,
+		LIBUSB_ENDPOINT_IN | LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_RECIPIENT_DEVICE,
 		HACKRF_VENDOR_REQUEST_SET_LNA_GAIN,
 		0,
 		value,
-		NULL,
-		0,
+		&retval,
+		1,
 		0
 	);
 
-	if( result != 0 )
+	if( result != 1 || !retval )
 	{
 		return HACKRF_ERROR_INVALID_PARAM;
 	} else {
@@ -832,6 +885,7 @@ int ADDCALL hackrf_set_lna_gain(hackrf_device* device, uint32_t value)
 int ADDCALL hackrf_set_vga_gain(hackrf_device* device, uint32_t value)
 {
 	int result;
+	uint8_t retval;
 	
 	if( value > 62 )
 	{
@@ -840,16 +894,16 @@ int ADDCALL hackrf_set_vga_gain(hackrf_device* device, uint32_t value)
 
 	result = libusb_control_transfer(
 		device->usb_device,
-		LIBUSB_ENDPOINT_OUT | LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_RECIPIENT_DEVICE,
+		LIBUSB_ENDPOINT_IN | LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_RECIPIENT_DEVICE,
 		HACKRF_VENDOR_REQUEST_SET_VGA_GAIN,
 		0,
 		value,
-		NULL,
-		0,
+		&retval,
+		1,
 		0
 	);
 
-	if( result != 0 )
+	if( result != 1 || !retval )
 	{
 		return HACKRF_ERROR_INVALID_PARAM;
 	} else {
@@ -860,6 +914,7 @@ int ADDCALL hackrf_set_vga_gain(hackrf_device* device, uint32_t value)
 int ADDCALL hackrf_set_txvga_gain(hackrf_device* device, uint32_t value)
 {
 	int result;
+	uint8_t retval;
 	
 	if( value > 47 )
 	{
@@ -868,16 +923,16 @@ int ADDCALL hackrf_set_txvga_gain(hackrf_device* device, uint32_t value)
 
 	result = libusb_control_transfer(
 		device->usb_device,
-		LIBUSB_ENDPOINT_OUT | LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_RECIPIENT_DEVICE,
+		LIBUSB_ENDPOINT_IN | LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_RECIPIENT_DEVICE,
 		HACKRF_VENDOR_REQUEST_SET_TXVGA_GAIN,
 		0,
 		value,
-		NULL,
-		0,
+		&retval,
+		1,
 		0
 	);
 
-	if( result != 0 )
+	if( result != 1 || !retval )
 	{
 		return HACKRF_ERROR_INVALID_PARAM;
 	} else {
diff --git a/host/libhackrf/src/hackrf.h b/host/libhackrf/src/hackrf.h
index 14968319..96d2dcf6 100644
--- a/host/libhackrf/src/hackrf.h
+++ b/host/libhackrf/src/hackrf.h
@@ -129,6 +129,7 @@ extern ADDAPI int ADDCALL hackrf_board_id_read(hackrf_device* device, uint8_t* v
 extern ADDAPI int ADDCALL hackrf_version_string_read(hackrf_device* device, char* version, uint8_t length);
 
 extern ADDAPI int ADDCALL hackrf_set_freq(hackrf_device* device, const uint64_t freq_hz);
+extern ADDAPI int ADDCALL hackrf_set_fracrate(hackrf_device* device, const float freq_mhz);
 
 /* external amp, bool on/off */
 extern ADDAPI int ADDCALL hackrf_set_amp_enable(hackrf_device* device, const uint8_t value);