USB Audio 2.0 - how to provide host with a range or list of supported sample frequencies ? Hello, In UAC 2, how should the MCU audio device provide the host with a list of supported sample rates ? Using SDK 2.16 dev_audio_speaker_freertos example on i.MXRT1010 evaluation board. In this example, is it correct that for UAC2 the supported sample rates are provided to the host via audio_speaker.c:USB_DeviceAudioRequest() returning freqControlRange for the GET_RANGE_SAMPLING_FREQ_CONTROL case ? Modifying audio_speaker.c:g_UsbDeviceAudioSpeaker.freqControlRange does not produce the expected results :- /* wNumSubRanges, wMIN, wMAX, wRES */
.freqControlRange = {1U, 48000U, 48000U, 0U} - host lists 48kHz - original values
.freqControlRange = {1U, 44100U, 48000U, 0U} - host lists 44.1kHz + 48kHz
.freqControlRange = {1U, 44100U, 96000U, 0U} - host lists 44,1kHz - expected a range 44.1kHz, 48kHz, 88.2kHz and 96kHz What am I missing ? Thanks. i.MXRT 101x i.MXRT 102x i.MXRT 106x Re: USB Audio 2.0 - how to provide host with a range or list of supported sample frequencies ? Hi @EdwinHz Apologies for this delayed reply, I've been away from NXP SDK for a while. I tested this example app as is, with SDK 2.8. Once I figure out which of the changes it introduces I require, I'll port them to the current SDK. It enumerates as follows :- $ lsusb -vd 1fc9:0032
Bus 001 Device 009: ID 1fc9:0032 NXP Semiconductors USB AUDIO+HID DEMO
Couldn't open device, some information will be missing
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0 [unknown]
bDeviceSubClass 0 [unknown]
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x1fc9 NXP Semiconductors
idProduct 0x0032 USB AUDIO+HID DEMO
bcdDevice 1.01
iManufacturer 1 NXP SEMICONDUCTORS
iProduct 2 USB AUDIO+HID DEMO
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 0x0146
bNumInterfaces 4
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xc0
Self Powered
MaxPower 500mA
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 0
bInterfaceCount 3
bFunctionClass 1 Audio
bFunctionSubClass 0 [unknown]
bFunctionProtocol 32
iFunction 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 1 Control Device
bInterfaceProtocol 32
iInterface 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdADC 2.00
bCategory 4
wTotalLength 0x006f
bmControls 0x00
AudioControl Interface Descriptor:
bLength 8
bDescriptorType 36
bDescriptorSubtype 10 (CLOCK_SOURCE)
bClockID 16
bmAttributes 3 Internal programmable clock
bmControls 0x07
Clock Frequency Control (read/write)
Clock Validity Control (read-only)
bAssocTerminal 0
iClockSource 0
AudioControl Interface Descriptor:
bLength 17
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Microphone
bAssocTerminal 0
bCSourceID 16
bNrChannels 2
bmChannelConfig 0x00000003
Front Left (FL)
Front Right (FR)
iChannelNames 0
bmControls 0x0000
iTerminal 0
AudioControl Interface Descriptor:
bLength 18
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 2
bSourceID 1
bmaControls(0) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(1) 0x00000000
bmaControls(2) 0x00000000
iFeature 0
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 3
wTerminalType 0x0101 USB Streaming
bAssocTerminal 1
bSourceID 2
bCSourceID 16
bmControls 0x0000
iTerminal 0
AudioControl Interface Descriptor:
bLength 8
bDescriptorType 36
bDescriptorSubtype 10 (CLOCK_SOURCE)
bClockID 18
bmAttributes 3 Internal programmable clock
bmControls 0x07
Clock Frequency Control (read/write)
Clock Validity Control (read-only)
bAssocTerminal 0
iClockSource 0
AudioControl Interface Descriptor:
bLength 17
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 4
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bCSourceID 18
bNrChannels 2
bmChannelConfig 0x00000003
Front Left (FL)
Front Right (FR)
iChannelNames 0
bmControls 0x0000
iTerminal 0
AudioControl Interface Descriptor:
bLength 18
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 5
bSourceID 4
bmaControls(0) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(1) 0x00000000
bmaControls(2) 0x00000000
iFeature 0
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 6
wTerminalType 0x0301 Speaker
bAssocTerminal 4
bSourceID 5
bCSourceID 18
bmControls 0x0000
iTerminal 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 0
AudioStreaming Interface Descriptor:
bLength 16
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 3
bmControls 0x00
bFormatType 1
bmFormats 0x00000001
PCM
bNrChannels 2
bmChannelConfig 0x00000003
Front Left (FL)
Front Right (FR)
iChannelNames 0
AudioStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bSubslotSize 3
bBitResolution 24
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x00c0 1x 192 bytes
bInterval 1
AudioStreaming Endpoint Descriptor:
bLength 8
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x00
bmControls 0x00
bLockDelayUnits 0 Undefined
wLockDelay 0x0000
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 0
AudioStreaming Interface Descriptor:
bLength 16
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 4
bmControls 0x00
bFormatType 1
bmFormats 0x00000001
PCM
bNrChannels 2
bmChannelConfig 0x00000003
Front Left (FL)
Front Right (FR)
iChannelNames 0
AudioStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bSubslotSize 2
bBitResolution 16
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 9
Transfer Type Isochronous
Synch Type Adaptive
Usage Type Data
wMaxPacketSize 0x00c0 1x 192 bytes
bInterval 1
AudioStreaming Endpoint Descriptor:
bLength 8
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x00
bmControls 0x00
bLockDelayUnits 0 Undefined
wLockDelay 0x0000
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 2
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 0
AudioStreaming Interface Descriptor:
bLength 16
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 4
bmControls 0x00
bFormatType 1
bmFormats 0x00000001
PCM
bNrChannels 2
bmChannelConfig 0x00000003
Front Left (FL)
Front Right (FR)
iChannelNames 0
AudioStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bSubslotSize 3
bBitResolution 24
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 9
Transfer Type Isochronous
Synch Type Adaptive
Usage Type Data
wMaxPacketSize 0x00c0 1x 192 bytes
bInterval 1
AudioStreaming Endpoint Descriptor:
bLength 8
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x00
bmControls 0x00
bLockDelayUnits 0 Undefined
wLockDelay 0x0000
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 3 Human Interface Device
bInterfaceSubClass 0 [unknown]
bInterfaceProtocol 0
iInterface 0
HID Device Descriptor:
bLength 9
bDescriptorType 33
bcdHID 1.00
bCountryCode 0 Not supported
bNumDescriptors 1
bDescriptorType 34 Report
wDescriptorLength 35
Report Descriptors:
** UNAVAILABLE **
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x84 EP 4 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 16 Thanks very much for finding and sharing this example. Best regards, Paul. Re: USB Audio 2.0 - how to provide host with a range or list of supported sample frequencies ? Hi @EdwinHz., Thank you so much for continuing to research this issue and for providing this example project which seems to tie in with some further research I have done. I will give it a try with SDK 2.8.0 and if successful, will then port to 2.16 as you suggest. I used Wireshark to capture the USB traffic for a known good UAC 2 device which enumerates as supporting the following sample rates. host requests sample rate rangehost requests sample rate range audio device responds with sample rate rangeaudio device responds with sample rate range That CONTROL response date decodes as follows :- numSubRanges
0x0a 00
min max res
0x44 ac 00 00, 44 ac 00 00, 00 00 00 00 - 44100 kHz
0x80 bb 00 00, 80 bb 00 00, 00 00 00 00 - 48000 kHz
0x88 58 01 00, 88 58 01 00, 00 00 00 00 - 88200 kHz
0x00 77 01 00, 00 77 01 00, 00 00 00 00 - 96000 kHz
0x10 b1 02 00, 10 b1 02 00, 00 00 00 00 - 176400 kHz
0x00 ee 02 00, 00 ee 02 00, 00 00 00 00 - 192000 kHz
0x20 62 05 00, 20 62 05 00, 00 00 00 00 - 352800 kHz
0x00 dc 05 00, 00 dc 05 00, 00 00 00 00 - 384000 kHz
0x40 c4 0a 00, 40 c4 0a 00, 00 00 00 00 - 705600 kHz
0x00 b8 0b 00, 00 b8 0b 00, 00 00 00 00 - 768000 kHz This seems to align with the structure of the sample rate data of the example you have provided. Thanks and regards, Paul. Re: USB Audio 2.0 - how to provide host with a range or list of supported sample frequencies ? Hi @paulw2,
While investigating about this issue, I encountered an old project based on SDK 2.8.0 that provides a host with a list of supported sample frequencies. Although older, I believe it can prove to be very useful for your application. I will attach here. Notice how the freqControlRange structure is expanded to include a wide range of frequencies:
g_deviceAudioComposite->audioUnified.freqControlRange1.wNumSubRanges = 6U;
g_deviceAudioComposite->audioUnified.freqControlRange1.wMIN = 44100U;
g_deviceAudioComposite->audioUnified.freqControlRange1.wMAX = 44100U;
g_deviceAudioComposite->audioUnified.freqControlRange1.wRES = 0U;
g_deviceAudioComposite->audioUnified.freqControlRange2.wMIN = 48000U;
g_deviceAudioComposite->audioUnified.freqControlRange2.wMAX = 48000U;
g_deviceAudioComposite->audioUnified.freqControlRange2.wRES = 0U;
g_deviceAudioComposite->audioUnified.freqControlRange3.wMIN = 88200U;
g_deviceAudioComposite->audioUnified.freqControlRange3.wMAX = 88200U;
g_deviceAudioComposite->audioUnified.freqControlRange3.wRES = 0U;
g_deviceAudioComposite->audioUnified.freqControlRange4.wMIN = 96000U;
g_deviceAudioComposite->audioUnified.freqControlRange4.wMAX = 96000U;
g_deviceAudioComposite->audioUnified.freqControlRange4.wRES = 0U;
g_deviceAudioComposite->audioUnified.freqControlRange5.wMIN = 176400U;
g_deviceAudioComposite->audioUnified.freqControlRange5.wMAX = 176400U;
g_deviceAudioComposite->audioUnified.freqControlRange5.wRES = 0U;
g_deviceAudioComposite->audioUnified.freqControlRange6.wMIN = 192000U;
g_deviceAudioComposite->audioUnified.freqControlRange6.wMAX = 192000U;
g_deviceAudioComposite->audioUnified.freqControlRange6.wRES = 0U;
If you wish to quickly test, you could download SDK2.8.0 and build with said SDK for your RT1010. Otherwise, I would recommend you port this implementation to your needs on the latest SDK2.16.0 for the best performance.
BR, Edwin. Re: USB Audio 2.0 - how to provide host with a range or list of supported sample frequencies ? Apologies, not sure where those bogus 'STRUCT_UNPACKED' came from. Re: USB Audio 2.0 - how to provide host with a range or list of supported sample frequencies ? Hi @EdwinHz, Further reading of, "USB Device Class Definition for Audio Devices", Release 2.0 May 31, 2006 89 :- Chapter 5 5.2 Class-Specific Requests 5.2.1 Control Attributes - concludes with the hypothetical Volume Control example :- • -∞ dB • -70 dB to -40 dB in steps of 3 dB • -40 dB to -20 dB in steps of 2 dB • -20 dB to 0 dB in steps of 1 dB One possible layout of the RANGE attribute is then: RANGE(0) = 3 RANGE(1) = [-70, -40, 3] RANGE(2) = [-38, -20, 2] RANGE(3) = [-19, 0, 1] Another way of representing the same Control is as follows: RANGE(0) = 3 RANGE(1) = [-70, -43, 3] RANGE(2) = [-40, -22, 2] RANGE(3) = [-20, 0, 1] Which suggests that supported sample rates could be represented as :- #if (USB_DEVICE_CONFIG_AUDIO_CLASS_2_0)
struct _usb_device_control_range_layout3_struct
{
uint32_t wMIN;
uint32_t wMAX;
uint32_t wRES;
} STRUCT_UNPACKED;
struct _usb_device_control_ranges_layout3_struct
{
uint16_t wNumSubRanges;
struct _usb_device_control_range_layout3_struct range[MAX_SAMPLE_RATES];
} STRUCT_UNPACKED;
typedef struct _usb_device_control_ranges_layout3_struct usb_device_control_ranges_layout3_struct_t;
#endif /* USB_DEVICE_CONFIG_AUDIO_CLASS_2_0 */ Or am I misunderstanding the documentation and/or the interface provided by the MCUXpresso SDK ? Thanks and regards, Paul. Re: USB Audio 2.0 - how to provide host with a range or list of supported sample frequencies ? Hi @EdwinHz, Thanks very much for your reply. As it happens, it was while working through AN13447 that I encountered this issue. Following the approach taken in AN13447 I was able to add 32 bit support but when adding additional sample rate frequencies encountered the following results (note failure in UAC 2.0 case) :- excerpt from usb_audio_descriptor.c: uint8_t g_UsbDeviceConfbDescriptorSubtypeigurationDescriptor[] Class 1.0 audio descriptor (USB_DEVICE_CONFIG_AUDIO_CLASS_2_0 == 0U) - single sample rate supported :- /* Audio Class Specific type I format INTERFACE Descriptor */
USB_AUDIO_STREAMING_TYPE_I_DESC_SIZE, /* bLength (11) */
USB_DESCRIPTOR_TYPE_AUDIO_CS_INTERFACE, /* bDescriptorType (CS_INTERFACE) */
USB_DESCRIPTOR_SUBTYPE_AUDIO_STREAMING_FORMAT_TYPE, /* bDescriptorSubtype: AUDIO STREAMING FORMAT TYPE */
USB_AUDIO_FORMAT_TYPE_I, /* bFormatType - Format Type: Type I */
AUDIO_FORMAT_CHANNELS, /* bNrChannels - Number of Channels: one channel */
AUDIO_FORMAT_SIZE, /* bSubFrameSize - SubFrame Size: one byte per audio subframe */
AUDIO_FORMAT_BITS, /* bBitResolution - Bit Resolution: 8 bits per sample */
0x01U, /* bSamFreqType - One sample frequency supported */
TSAMFREQ2BYTES(AUDIO_SAMPLING_RATE_KHZ * 1000), /* 3 bytes - 48 kHz */ lsusb -v reports :-
AudioStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 2
bSubframeSize 4
bBitResolution 32
bSamFreqType 1 Discrete
tSamFreq[ 0] 48000 Class 1.0 audio descriptor (USB_DEVICE_CONFIG_AUDIO_CLASS_2_0 == 0U) - two sample rates supported :- /* Audio Class Specific type I format INTERFACE Descriptor */
USB_AUDIO_STREAMING_TYPE_I_DESC_SIZE + 3, /* bLength (14) */
USB_DESCRIPTOR_TYPE_AUDIO_CS_INTERFACE, /* bDescriptorType (CS_INTERFACE) */
USB_DESCRIPTOR_SUBTYPE_AUDIO_STREAMING_FORMAT_TYPE, /* bDescriptorSubtype: AUDIO STREAMING FORMAT TYPE */
USB_AUDIO_FORMAT_TYPE_I, /* bFormatType - Format Type: Type I */
AUDIO_FORMAT_CHANNELS, /* bNrChannels - Number of Channels: one channel */
AUDIO_FORMAT_SIZE, /* bSubFrameSize - SubFrame Size: one byte per audio subframe */
AUDIO_FORMAT_BITS, /* bBitResolution - Bit Resolution: 8 bits per sample */
0x02U, /* bSamFreqType - Two sample frequencies supported */
TSAMFREQ2BYTES(AUDIO_SAMPLING_RATE_KHZ * 1000), /* 3 bytes - 48 kHz */
TSAMFREQ2BYTES(72 * 1000), /* 3 bytes - 72 kHz */ lsbusb -v reports :-
AudioStreaming Interface Descriptor:
bLength 14
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 2
bSubframeSize 4
bBitResolution 32
bSamFreqType 2 Discrete
tSamFreq[ 0] 48000
tSamFreq[ 1] 72000 Class 2.0 audio descriptor (USB_DEVICE_CONFIG_AUDIO_CLASS_2_0 == 1U) - two sample rates supported :- /* Audio Class Specific type I format INTERFACE Descriptor */
USB_AUDIO_STREAMING_TYPE_I_DESC_SIZE + 3, /* bLength (14) */
USB_DESCRIPTOR_TYPE_AUDIO_CS_INTERFACE, /* bDescriptorType (CS_INTERFACE) */
USB_DESCRIPTOR_SUBTYPE_AUDIO_STREAMING_FORMAT_TYPE, /* bDescriptorSubtype: AUDIO STREAMING FORMAT TYPE */
USB_AUDIO_FORMAT_TYPE_I, /* bFormatType - Format Type: Type I */
AUDIO_FORMAT_CHANNELS, /* bNrChannels - Number of Channels: one channel */
AUDIO_FORMAT_SIZE, /* bSubFrameSize - SubFrame Size: one byte per audio subframe */
AUDIO_FORMAT_BITS, /* bBitResolution - Bit Resolution: 8 bits per sample */
0x02U, /* bSamFreqType - Two sample frequencies supported */
TSAMFREQ2BYTES(AUDIO_SAMPLING_RATE_KHZ * 1000), /* 3 bytes - 48 kHz */
TSAMFREQ2BYTES(72 * 1000), /* 3 bytes - 72 kHz */ lsbusb -v reports :-
AudioStreaming Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bSubslotSize 4
bBitResolution 32
junk at descriptor end: 02 80 bb 00 40 19 01 Various documentation including, USB Device Class Definition for Audio Devices - Release 2.0, state that in UAC2 the supported sample rates are requested by the host and provided by the device in the Minimum (MIN), Maximum (MAX), and Resolution (RES) format listed in my original question. As stated initially, the following changes to audio_speaker.c did enable the host to determine the device supported 2 sample rates. g_UsbDeviceAudioSpeaker.freqControlRange = {1U, 44100U, 48000U, 0U}, // gives 44.1 + 48 This looks to be on the right track for UAC 2 but more info is needed on how to properly utilise this interface. Thanks and regards, Paul. Re: USB Audio 2.0 - how to provide host with a range or list of supported sample frequencies ? Hi @paulw2,
Thanks for the clarification. In this case, you would have to add alternate interface setting for each desired supported audio format (i.e. 3 for 44.100 Hz, 48,000 Hz and 88,200 Hz). This can be done by following this application note: AN13447.pdf (nxp.com). Even though it is technically describing the process for an LPC, it is still the same for the RT1010.
BR, Edwin. Re: USB Audio 2.0 - how to provide host with a range or list of supported sample frequencies ? Hi @EdwinHz Thanks very much for replying to my question. Using a resolution of 1 enumerates as 44,100 Hz, 44,101 Hz, 44,102 Hz, ...... 44,160 Hz Using a resolution of 10 enumerates as 44,100 Hz, 44,110 Hz, 44,120 Hz, ...... 45,440 Hz The resolution member does not seem to lend itself to providing the host with a list of supported sample rates such as :- 44.100 Hz 48,000 Hz 88,200 Hz 96,000 Hz 176,400 Hz 192,000 Hz 352,000 Hz 384,000 Hz 705,000 Hz 768,000 Hz Perhaps I should have been clearer on these sample rates. What would be the correct method of specifying these as the supported sample rates for UAC 2 ? Thanks and regards, Paul. Re: USB Audio 2.0 - how to provide host with a range or list of supported sample frequencies ? Hi @paulw2,
Please try changing the resolution (wRES) value to 1 or more to achieve higher number of frequencies. As such:
.freqControlRange = {1U, 44100U, 48000U, 1U}
BR, Edwin.
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