diff --git a/lib_xua/api/xua_usb_params_funcs.h b/lib_xua/api/xua_usb_params_funcs.h
new file mode 100644
index 00000000..460c4008
--- /dev/null
+++ b/lib_xua/api/xua_usb_params_funcs.h
@@ -0,0 +1,16 @@
+// Copyright (c) 2017-2020, XMOS Ltd, All rights reserved
+
+#ifndef __XUA_API_H__
+#define __XUA_API_H__
+
+extern void set_usb_to_device_rate(uint32_t rate);
+extern void set_device_to_usb_rate(uint32_t rate);
+extern void set_usb_to_device_bit_res(uint32_t rate);
+extern void set_device_to_usb_bit_res(uint32_t rate);
+
+extern uint32_t get_usb_to_device_rate();
+extern uint32_t get_device_to_usb_rate();
+extern uint32_t get_usb_to_device_bit_res();
+extern uint32_t get_device_to_usb_bit_res();
+
+#endif  //__XUA_API_H__
diff --git a/lib_xua/src/core/buffer/decouple/decouple.xc b/lib_xua/src/core/buffer/decouple/decouple.xc
index b6dffe51..f217b0e4 100644
--- a/lib_xua/src/core/buffer/decouple/decouple.xc
+++ b/lib_xua/src/core/buffer/decouple/decouple.xc
@@ -7,6 +7,7 @@
 #include "interrupt.h"
 #include "xua_commands.h"
 #include "xud.h"
+#include "xua_usb_params_funcs.h"
 
 #ifdef NATIVE_DSD
 #include "usbaudio20.h"             /* Defines from the USB Audio 2.0 Specifications */
@@ -17,12 +18,6 @@
 #endif
 #define MAX(x,y) ((x)>(y) ? (x) : (y))
 
-#if(defined USB_DESCRIPTOR_OVERRIDE_RATE_RES)
-extern uint32_t get_usb_to_device_rate();
-extern uint32_t get_device_to_usb_rate();
-extern uint32_t get_usb_to_device_bit_res();
-extern uint32_t get_device_to_usb_bit_res();
-#endif
 
 /* TODO use SLOTSIZE to potentially save memory */
 /* Note we could improve on this, for one subslot is set to 4 */
@@ -165,7 +160,7 @@ int g_maxPacketSize = MAX_DEVICE_AUD_PACKET_SIZE_IN_FS;
 void handle_audio_request(chanend c_mix_out)
 {
     int space_left;
-#if(defined USB_DESCRIPTOR_OVERRIDE_RATE_RES)
+#if(defined XUA_USB_DESCRIPTOR_OVERWRITE_RATE_RES)
     g_curSubSlot_Out = get_usb_to_device_bit_res() >> 3;
     g_curSubSlot_In = get_device_to_usb_bit_res() >> 3;
 #endif
diff --git a/lib_xua/src/core/endpoint0/xua_endpoint0.c b/lib_xua/src/core/endpoint0/xua_endpoint0.c
index 18ae1ee6..2a183c72 100755
--- a/lib_xua/src/core/endpoint0/xua_endpoint0.c
+++ b/lib_xua/src/core/endpoint0/xua_endpoint0.c
@@ -29,6 +29,8 @@
 #include "dsd_support.h"
 #endif
 
+#include "xua_usb_params_funcs.h"
+
 #ifndef __XC__
 /* Support for xCORE  channels in C */
 #define null 0
@@ -65,13 +67,6 @@ extern void device_reboot(void);
 #include "xua_hid.h"
 #endif
 
-#if(defined USB_DESCRIPTOR_OVERRIDE_RATE_RES)
-extern uint32_t get_usb_to_device_rate();
-extern uint32_t get_device_to_usb_rate();
-extern uint32_t get_usb_to_device_bit_res();
-extern uint32_t get_device_to_usb_bit_res();
-#endif
-
 unsigned int DFU_mode_active = 0;         // 0 - App active, 1 - DFU active
 
 /* Global volume and mute tables */
@@ -344,7 +339,7 @@ void XUA_Endpoint0_init(chanend c_ep0_out, chanend c_ep0_in, chanend c_audioCont
     }
 #endif
 
-#ifdef USB_DESCRIPTOR_OVERRIDE_RATE_RES	//change USB descriptor frequencies and bit resolution values here
+#ifdef XUA_USB_DESCRIPTOR_OVERWRITE_RATE_RES	//change USB descriptor frequencies and bit resolution values here
 
     cfgDesc_Audio1[USB_AS_IN_INTERFACE_DESCRIPTOR_OFFSET_SUB_FRAME] = get_device_to_usb_bit_res() >> 3; 	//sub frame rate = bit rate /8
     cfgDesc_Audio1[USB_AS_IN_INTERFACE_DESCRIPTOR_OFFSET_SUB_FRAME + 1] = (get_device_to_usb_bit_res() & 0xff);		//bit resolution
@@ -352,7 +347,7 @@ void XUA_Endpoint0_init(chanend c_ep0_out, chanend c_ep0_in, chanend c_audioCont
     cfgDesc_Audio1[USB_AS_OUT_INTERFACE_DESCRIPTOR_OFFSET_SUB_FRAME] = get_usb_to_device_bit_res() >> 3; 	//sub frame rate = bit rate /8
     cfgDesc_Audio1[USB_AS_OUT_INTERFACE_DESCRIPTOR_OFFSET_SUB_FRAME + 1] = (get_usb_to_device_bit_res() & 0xff);		//bit resolution
     
-    const unsigned num_of_usb_descriptor_freq=3;	//This should be =3 according to the comments "sing a value of <=2 or > 7 for num_freqs_a1 causes enumeration issues on Windows" in xua_ep0_descriptors.h
+    const unsigned num_of_usb_descriptor_freq=3;	//This should be =3 according to the comments "using a value of <=2 or > 7 for num_freqs_a1 causes enumeration issues on Windows" in xua_ep0_descriptors.h
     int i=0;
     for(i=0;i<num_of_usb_descriptor_freq;i++)
     {
diff --git a/lib_xua/src/core/endpoint0/xua_ep0_descriptors.h b/lib_xua/src/core/endpoint0/xua_ep0_descriptors.h
index c66c6dba..5e51b3dd 100644
--- a/lib_xua/src/core/endpoint0/xua_ep0_descriptors.h
+++ b/lib_xua/src/core/endpoint0/xua_ep0_descriptors.h
@@ -2367,7 +2367,7 @@ const unsigned num_freqs_a1 = MAX(3, (0
 #define CFG_TOTAL_LENGTH_A1         (18 + AC_TOTAL_LENGTH + (INPUT_INTERFACES_A1 * (49 + num_freqs_a1 * 3)) + (OUTPUT_INTERFACES_A1 * (49 + num_freqs_a1 * 3)) + CONTROL_INTERFACE_BYTES + DFU_INTERFACE_BYTES + HID_INTERFACE_BYTES)
 #endif
 
-#ifdef USB_DESCRIPTOR_OVERRIDE_RATE_RES
+#ifdef XUA_USB_DESCRIPTOR_OVERWRITE_RATE_RES
 	#define AS_INTERFACE_BYTES		(7)
 	#define INTERFACE_DESCRIPTOR_BYTES		(9)
 	#define AS_FORMAT_TYPE_BYTES		(17)