XU316 USB HiFi Decoder Zero-Development Product Configuration Protocol¶

Joint Support
XMOS Website: www.xmos.com
Phaten Audio Website: www.phaten-audio.com

Protocol Overview ¶

Function Positioning and Scope

This document provides a detailed description of the configuration protocol for communication between the XU316 USB HiFi Decoder zero-development product and MCU via UART. This protocol offers a complete feature set for audio device configuration, status monitoring, and media control.

I. Protocol Foundation Specifications ¶

1.1 Underlying Communication Protocol¶

Based on UART (Universal Asynchronous Receiver/Transmitter) Protocol

Parameter	Value
Baud Rate	115200 bps
Data Bits	8
Parity	None
Stop Bits	1
Flow Control	None

1.2 Frame Format and Data Transmission¶

Universal Frame Format

All commands and responses follow the following frame format:

Field	Bytes	Description
Frame Header	2	Fixed as 0x55aa
Version	1	Protocol version number
Command Word	1	Indicates frame function
Data Length	1	Length N of subsequent data, excluding the final checksum byte
Data	N	Specific data content
Checksum	1	Sum of bytes starting from frame header, result modulo 256

Data Transmission Notes

All data larger than 1 byte is transmitted using big-endian mode. Sample data in the protocol is represented in hexadecimal.

1.3 Communication Mechanism¶

1.3.1 Acknowledgment Mechanism¶

Acknowledgment and Timeout Handling

All commands require acknowledgment from the other party
Default command timeout is 300ms, communication failure is assumed after timeout
Special commands may have different timeout periods, which will be specified in the respective command descriptions

1.3.2 Retry and Fault Tolerance Mechanism¶

flowchart TD
    A[Send Command] --> B{Wait for Response}
    B -->|Timeout| C[Retransmit Command]
    C --> D{Retry Count < 4?}
    D -->|Yes| B
    D -->|No| E[Use Default Configuration]
    B -->|Response Received| F[Process Response]

II. Device Startup and Initialization ¶

2.1 Startup Interaction Flow¶

sequenceDiagram
    participant XU316
    participant MCU
    participant Flash

    rect
        Note over XU316,Flash: System Loader Firmware


        rect 
            Note over XU316,MCU: Power-up Startup Phase
            XU316->>MCU: Send startup command (0x00)
            Note over XU316: 
            alt Timeout without response (max 4 attempts, if no response after 4 attempts, directly enter USB->I2S mode)
                XU316->>MCU: Retransmit startup command (0x00)
            end
            MCU-->>XU316: Return startup options
            Note over XU316: Parse startup options
        end

        rect 
            Note over XU316,Flash: Basic Information Update Phase
            alt Startup option doesn't include 0x01 (don't update basic product information)
                XU316->>Flash: Read basic product information
                Flash-->>XU316: Return basic product information
            else Startup option includes 0x01 (update basic product information) or incomplete data read from Flash
                XU316->>MCU: Send read basic product information command (0x01)
                MCU-->>XU316: Return new basic product information
                XU316->>Flash: Save configuration
            end
        end

        rect 
            Note over XU316,Flash: Power-up Configuration Retrieval Phase
            alt Startup option doesn't include 0x02 (don't update power-up configuration)
                XU316->>Flash: Read power-up configuration
                Flash-->>XU316: Return power-up configuration data
            else Startup option includes 0x02 (update power-up configuration) or incomplete data read from Flash
                XU316->>MCU: Send get power-up configuration command (0x02)
                MCU-->>XU316: Return new power-up configuration
                XU316->>Flash: Save new power-up configuration
            end            
        end

        rect 
            Note over XU316: Loading Application Mode Phase
            XU316->>MCU: Send get current mode command (0x03)
            MCU-->>XU316: Return current mode
            Note over XU316: Load corresponding mode based on current mode
         end

    end

    rect 
        Note over XU316,MCU: APP Running Phase
        XU316->>MCU: Get current user configuration command (0x04)
        MCU-->>XU316: Return current user configuration
        Note over XU316: Initialize APP and apply current user configuration
        XU316->>MCU: Send startup completion command (0x05)
        MCU-->>XU316: Return completion command response
        par Parallel Processing
            loop Status Reporting
                XU316->>MCU: Status change or 15S periodic transmission
            end
            loop Business Processing
                MCU->>XU316: Send business instructions
                XU316-->>MCU: Respond to business instructions
            end
        end
    end

2.2 Detailed Startup Flow Description¶

Power-up Startup and Options PhaseBasic Information Update PhasePower-up Configuration Retrieval PhaseApplication Firmware Loading PhaseApplication Initialization Phase

XU316 startup sends startup command (command word 0x00) to MCU, containing:
- UAC1.0 VID/PID
- UAC2.0 VID/PID
- Basic information CRC
- Power-up configuration information CRC
MCU receives startup command, checks if information needs updating, and sends corresponding response
XU316 waits for MCU response
If timeout without response, XU316 retransmits startup command up to 4 times
If still no response, directly load default USB configuration and enumerate USB
If normal response received, XU316 parses startup options

Execution Condition: Startup option includes 0x01 (update basic product information)

Steps:

XU316 sends 0x01 command to request reading basic product information
MCU returns new basic product information to XU316
XU316 updates and saves configuration to internal storage

Execution Condition: Startup option includes 0x02 (update power-up configuration) or incomplete data read from Flash

Steps:

XU316 sends 0x02 command to request power-up configuration
MCU returns new power-up configuration to XU316
XU316 updates and saves configuration to internal storage

Steps:

XU316 sends 0x03 command to get current input/output mode
MCU returns current mode information to XU316
XU316 loads corresponding input/output mode based on returned mode

Steps:

XU316 sends 0x04 command to get current user configuration
MCU returns current user configuration to XU316
XU316 initializes application and applies related configuration
XU316 sends 0x05 command to indicate startup completion
MCU returns acknowledgment response

III. Protocol Command Set ¶

3.1 Command Classification Overview¶

Startup and Basic Commands (0x00-0x0F)Business Control Commands (0x20-0x2F)HID-MCU Mutual Transparent Transmission Commands (0xEE-0xEF)DAC Control Commands (0xF0-0xFF)

Command Word	Command Description	Direction
0x00	Start Startup	XU316→MCU
0x01	Read Product Information	XU316→MCU
0x02	Read Power-up Configuration Information	XU316→MCU
0x03	Get Current Input/Output Mode	XU316→MCU
0x04	Get Current User Configuration	XU316→MCU
0x05	Startup Completion Command	XU316→MCU

Command Word	Command Description	Direction
0x20	Report Application Status	XU316→MCU
0x21	Media Control	MCU→XU316
0x22	Report Playback Audio Stream Format and Type	XU316→MCU
0x23	Set Input/Output Mode	MCU→XU316
0x24	Send Playback Volume	MCU→XU316
0x25	Send Recording Volume	MCU→XU316
0x26	Switch MCLK	MCU→XU316

Command Word	Command Description	Direction
0xEE	HID-initiated command transmitted to MCU via XU316	XU316→MCU

Command Word	Command Description	Direction
0xF0	DAC Configuration Selection Command	MCU→XU316

Command Usage Instructions

All commands must follow basic frame format specifications
Each command requires acknowledgment from the other party before being considered successfully executed
Business control commands (0x20 and above) can only be used after device startup is completed

3.2 Basic Function Commands Detailed Explanation¶

3.2.1 Start Startup (0x00)¶

Command FormatFunction DescriptionUsage FlowNotes

XU316 Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x00
Data Length: 1 byte - 17
Data:    17 bytes
          B0:     Restart reason (0x00 power-up restart, 0x01 mode switch restart, 0xFF other reasons)
          B1-2:   USB Vendor ID (UAC1.0)
          B3-4:   USB Product ID (UAC1.0)
          B5-6:   USB Vendor ID (UAC2.0)
          B7-8:   USB Product ID (UAC2.0)
          B9-12:  Basic information 32bit CRC
          B13-16: Power-up configuration information 32bit CRC
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

MCU Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x00
Data Length: 1 byte - 0x1
Data:    1 byte
          B0: Startup options
              0x00 Use all default information
              0x01 Need to update basic product information
              0x02 Need to update power-up configuration information
              0x04 Need to update other configuration information
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is sent first after XU316 power-up or restart to inform MCU that the device has started
XU316 sends the currently stored product information CRC and configuration information CRC to MCU
MCU determines whether to update configuration information in XU316 by comparing CRC
MCU informs XU316 of subsequent operations to be performed through the startup options field in the response

flowchart TB
    A[XU316 Startup] -->B[Send 0x00 Command]
    B -->C{MCU Response}
    C -->|Timeout| D[Retransmit Command]
    D -->E{Retry Count < 4?}
    E -->|Yes| C
    E -->|No| F[Use Default Configuration]
    C -->|Normal Response| G[Parse Startup Options]
    G -->|0x01| H[Update Basic Product Information]
    G -->|0x02| I[Update Power-up Configuration Information]
    G -->|0x04| J[Update Other Configuration Information]
    G -->|0x00| K[Continue Startup Process]

If MCU has no response, XU316 will continue startup using stored default configuration
The restart reason field can be used by MCU to identify the specific reason for XU316 restart for different processing
When multiple pieces of information need to be updated, MCU can combine multiple options through bit operations

3.2.2 Read Product Information (0x01)¶

Command FormatFunction DescriptionData Structure

XU316 Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x01
Data Length: 1 byte - 0x00
Data:    0 bytes
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

MCU Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x01
Data Length: 1 byte - 0x3C (60 bytes)
Data:    60 bytes - Product basic information, see data field description for details
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used by XU316 to obtain basic product information, such as VID/PID, product name, etc.
Execution condition: Startup option includes 0x01 flag or product information CRC mismatch
After receiving this information, XU316 will update the internally stored basic product information

Product basic information data structure (60 bytes):

VID1 (UAC1.0):        2 bytes
PID1 (UAC1.0):        2 bytes
VID2 (UAC2.0):        2 bytes
PID2 (UAC2.0):        2 bytes
ManufactureName:     16 bytes (string)
ProductName:         16 bytes (string)
SerialNumber:        16 bytes (string)
CRC:                  4 bytes (32-bit CRC check)

3.2.3 Read Power-up Configuration Information (0x02)¶

Command FormatFunction DescriptionData Structure

XU316 Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x02
Data Length: 1 byte - 0x00
Data:    0 bytes - No data
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

MCU Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x02
Data Length: 1 byte - 0x0E (i.e., 14 bytes)
Data:    14 bytes - Power-up configuration information, see 4.1-Power-up Configuration Parameters
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used by XU316 to obtain initial power-up configuration information
Execution condition: Startup option includes 0x02 flag or power-up configuration CRC mismatch
XU316 will set default input/output mode, volume and other parameters according to this configuration information

Power-up configuration information data structure (14 bytes):

Default Input/Output Mode:          5 bytes
Mute Time:              2 bytes (0-65535ms)
Microphone Default Volume:        1 byte
DAC Left Channel Default Volume:     1 byte
DAC Right Channel Default Volume:     1 byte
CRC:                   4 bytes (32-bit CRC check)

3.2.4 Get Current Input/Output Mode (0x03)¶

Command FormatFunction Description

XU316 Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x03
Data Length: 1 byte - 0x00
Data:    0 bytes
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

MCU Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x03
Data Length: 1 byte - 0x05 (i.e., 5 bytes)
Data:    5 bytes - Input/Output mode, see data field section
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used by XU316 to query the current input/output mode that needs to be enabled during startup
XU316 will load the corresponding application firmware based on the returned mode
This command is used for mode matching and confirmation during device startup process

3.2.5 Get Current User Configuration (0x04)¶

Command FormatFunction Description

XU316 Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x04
Data Length: 1 byte - 0x00
Data:    0 bytes
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

MCU Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x04
Data Length: 1 byte - 0xE (i.e., 14 bytes)
Data:    14 bytes - User configuration parameters, see 4.1-User Configuration Parameters
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used by XU316 to obtain current user-selected configurations such as volume, mode, etc.
Executed after application firmware is loaded and before application startup
The application will initialize corresponding parameters based on the returned information

3.2.6 Startup Completion Command (0x05)¶

Command FormatFunction Description

XU316 Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x05
Data Length: 1 byte - N
Data:    N bytes
          B0: Startup status (0 startup successful, 1 mode mismatch, other values startup failed)
          B1-BN: Application runtime parameters, see 4.1-Runtime Parameters
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

MCU Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x05
Data Length: 1 byte - 0x00
Data:    0 bytes
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command indicates that the XU316 startup process is completed and normal operation can begin
Contains startup status information to inform MCU whether startup was successful or encountered problems
All subsequent business commands can only be used after this command is successfully sent

3.3 Business Control Commands Detailed Explanation¶

Prerequisites

The following commands can only be used after XU316 startup is completed (after sending 0x05 command and receiving response)

3.3.1 Report Application Status (0x20)¶

Command FormatFunction Description

XU316 Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x20
Data Length: 1 byte - N
Data:    N bytes - Application runtime parameters, see 4.1-Runtime Parameters
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

MCU Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x20
Data Length: 1 byte - 0x00
Data:    0 bytes
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used by XU316 to report current application status to MCU
Usually sent when status changes, such as volume changes, mode switching, etc.
MCU can update UI display or adjust related functions based on this information

3.3.2 Media Control (0x21)¶

Command FormatFunction DescriptionControl Button Mapping Table

MCU Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x21
Data Length: 1 byte - 0x01 (i.e., 1 byte)
Data:    1 byte - Media control command
          0x00 Volume+ / Vol Up
          0x01 Volume- / Vol Down
          0x02 Play/Pause / PLAY/PAUSE
          0x03 Next Track / NEXT
          0x04 Previous Track / PREV
          0x05 Fast Forward / FORWARD
          0x06 Rewind / REWIND
          0x07 Mute / MUTE
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

XU316 Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x21
Data Length: 1 byte - 0x00
Data:    0 bytes
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used by MCU to send media control instructions to XU316
After receiving the instruction, XU316 will convert it to corresponding HID commands and send to the computer
Suitable for implementing remote control or physical button control of media playback

Control Code	Function	USB HID Usage
0x00	Volume+	Increase system volume
0x01	Volume-	Decrease system volume
0x02	Play/Pause	Control media playback status
0x03	Next Track	Switch to next song
0x04	Previous Track	Switch to previous song
0x05	Fast Forward	Fast forward in current track
0x06	Rewind	Rewind in current track
0x07	Mute	Toggle system mute status

3.3.3 Report Playback Audio Stream Format and Type (0x22)¶

Command FormatFunction Description

XU316 Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x22
Data Length: 1 byte - 0x02 (i.e., 2 bytes)
Data:    2 bytes - Audio stream format and type, see audio stream format and type fields
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

MCU Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x22
Data Length: 1 byte - 0x00
Data:    0 bytes
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used by XU316 to report the current audio stream format and type to MCU
Usually sent when playback starts or format changes
MCU can update display based on this information, such as showing PCM/DSD/MQA/DOP status

3.3.4 Set Input/Output Mode (0x23)¶

Command FormatFunction Description

MCU Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x23
Data Length: 1 byte - 0x05 (i.e., 5 bytes)
Data:    5 bytes - Input/Output mode, see input/output mode fields
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

XU316 Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x23
Data Length: 1 byte - 0x00
Data:    0 bytes
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used by MCU to request XU316 to switch to a specific input/output mode
Usually triggered by user operation, such as pressing mode selection button
XU316 may need to restart to load firmware for the new mode

3.3.5 Send Playback Volume (0x24)¶

Command FormatFunction Description

MCU Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x24
Data Length: 1 byte - 0x02 (i.e., 2 bytes)
Data:    2 bytes
          Byte 1: Left channel (0xFF Mute, 0-0dB, -127: -127dB)
          Byte 2: Right channel (0xFF Mute, 0-0dB, -127: -127dB)
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

XU316 Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x24
Data Length: 1 byte - 0x00
Data:    0 bytes
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used by MCU to set the current playback volume to XU316

3.3.6 Send Recording Volume (0x25)¶

Command FormatFunction Description

MCU Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x25
Data Length: 1 byte - 0x01 (i.e., 1 byte)
Data:    1 byte - 0xFF Mute, 0-0dB -127: -127dB
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

XU316 Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x25
Data Length: 1 byte - 0x00
Data:    0 bytes
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used by MCU to set the current microphone recording volume to XU316

3.3.7 Switch MCLK (0x26)¶

Command FormatFunction Description

MCU Sends

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x03
Command Word:   1 byte - 0x26
Data Length: 1 byte - 1
Data:    1 byte - 0: Internal MCLK, 1: External MCLK
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

XU316 Returns

Frame Header:    2 bytes - 0x55aa
Version:    1 byte - 0x00
Command Word:   1 byte - 0x26
Data Length: 1 byte - 0
Data:    0 bytes
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used by XU316 to control switching of the master clock source
Can switch between using internal clock or external clock
Important for certain audio application scenarios requiring precise synchronization

3.3.8 Set unmute (0x27)¶

Command FormatFunction Description

Sent by MCU

Frame Header:  2 bytes - 0x55aa
Version:       1 byte - 0x03
Command Word:  1 byte - 0x27
Data Length:   1 byte - 2
Data:          2 bytes - 
Checksum:      1 byte - Sum the bytes starting from the frame header, and take the remainder of the result divided by 256

Returned by XU316

Frame Header:  2 bytes - 0x55aa
Version:       1 byte - 0x00
Command Word:  1 byte - 0x27
Data Length:   1 byte - 0
Data:          0 bytes
Checksum:      1 byte - Sum the bytes starting from the frame header, and take the remainder of the result divided by 256

The unmute time delay of the DAC during mode switching, with the unit being milliseconds.

3.3.9 Time Delay for Sending Audio Format (0x28)¶

Command FormatFunction Description

Sent by MCU

Frame Header:  2 bytes - 0x55aa
Version:       1 byte - 0x03
Command Word:  1 byte - 0x28
Data Length:   1 byte - 2
Data:          2 bytes - 
Checksum:      1 byte - Sum the bytes starting from the frame header, and take the remainder of the result divided by 256

Returned by XU316

Frame Header:  2 bytes - 0x55aa
Version:       1 byte - 0x00
Command Word:  1 byte - 0x28
Data Length:   1 byte - 0
Data:          0 bytes
Checksum:      1 byte - Sum the bytes starting from the frame header, and take the remainder of the result divided by 256

The time delay for sending the audio format.

3.3.10 Command to Get Firmware Version (0xF1)¶

Command FormatFunction Description

Sent by MCU

Frame Header:  2 bytes - 0x55aa
Version:       1 byte - 0x03
Command Word:  1 byte - 0xF1
Data Length:   1 byte - 2
Data:          2 bytes - 
Checksum:      1 byte - Sum the bytes starting from the frame header, and take the remainder of the result divided by 256

Returned by XU316

Frame Header:  2 bytes - 0x55aa
Version:       1 byte - 0x00
Command Word:  1 byte - 0xF1
Data Length:   1 byte - 0
Data:          0 bytes
Checksum:      1 byte - Sum the bytes starting from the frame header, and take the remainder of the result divided by 256

To get the firmware version.

3.4 DAC Configuration Selection (0xF0)¶

Command FormatFunction Description

Sent by MCU

Frame Header:  2 bytes - 0x55aa
Version:       1 byte - 0x03
Command Word:  1 byte - 0xF0
Data Length:   1 byte - 4
Data:        4 bytes
             Byte 0: 0: Enable I2C configuration DAC  1: Disable I2C configuration DAC
             Byte 1 - 3: reserved
Checksum:   1 byte - Sum of bytes starting from frame header, result modulo 256

XU316 Returns

Frame Header:    2 bytes - 0x55aa
Version:         1 byte - 0x00
Command Word:    1 byte - 0xF0
Data Length:     1 byte - 0
Data:            0 bytes
Checksum:        1 byte - Sum of bytes starting from frame header, result modulo 256

Test command used by MCU to set DAC configuration selection to XU316. Let XU316 configure DAC through DAC I2C or let MCU configure DAC itself
This command is product-specific and not all products support it. Please refer to product specification for specific support details.

3.5 HID and MCU Data Transparent Transmission Commands via XU316¶

3.5.1 HID Transparent Transmission Data to MCU via XU316 (0xEE)¶

Command FormatFunction Description

XU316 Sends

Frame Header:    2 bytes - 0x55aa
Version:        1 byte - 0x00
Command Word:   1 byte - 0xEE
Data Length:    1 byte - 0x39 (57 bytes), due to HID protocol limitations, data length must be 57 bytes
Data:           57 bytes - Due to HID protocol limitations, must be 57 bytes transparent transmission data
Checksum:       1 byte - Sum of bytes starting from frame header, result modulo 256

MCU Returns (can return multiple frames)

Frame Header:    2 bytes - 0x55aa
Version:         1 byte - 0x03
Command Word:    1 byte - 0xEE
Data Length:     1 byte - 0x39 (57 bytes), due to HID protocol limitations, data length must be 57 bytes
Data:            57 bytes - Due to HID protocol limitations, must be 57 bytes transparent transmission data
Checksum:        1 byte - Sum of bytes starting from frame header, result modulo 256

This command is used for transparent data transmission initiated by HID to MCU via XU316
Generally, the transparent transmission data is MCU's OTA data or MCU data reply to HID

IV. Data Structure Definitions ¶

4.1 Product Configuration Data Structures¶

1. Product Basic Information2. Power-up Configuration Information3. Application Runtime Parameters4. User Configuration Parameters

Field	Bytes	Description
VID1	2	USB Vendor ID (UAC1.0)
PID1	2	USB Product ID (UAC1.0)
VID2	2	USB Vendor ID (UAC2.0)
PID2	2	USB Product ID (UAC2.0)
ManufactureName	16	USB Manufacture Name (string, max 16 bytes)
ProductName	16	USB Product Name (string, max 16 bytes)
SerialNumber	16	Product Serial Number (string, max 16 bytes)
CRC	4	32-bit CRC check value calculated for all fields

CRC Usage Instructions

MCU can determine whether to update basic product information based on the CRC value returned by XU316. When CRC does not match, complete basic product information should be sent.

Field	Bytes	Description
Default Input/Output Mode	5	See input/output mode field description
Mute Time	2	0-65535 (ms)
Microphone Default Volume	1	See microphone volume field description
DAC Left Channel Default Volume	1	See DAC volume field description
DAC Right Channel Default Volume	1	See DAC volume field description
CRC	4	32-bit CRC check value calculated for all fields

Field	Bytes	Description
Input/Output Mode	5	See input/output mode field description
Mute Time	2	0-65535 (ms)
Microphone Volume	1	See microphone volume field description
DAC Left Channel Volume	1	See DAC volume field description
DAC Right Channel Volume	1	See DAC volume field description
CRC	4	32-bit CRC check value calculated for all fields

Field	Bytes	Description
Input/Output Mode	5	See input/output mode field description
Mute Time	2	0-65535 (ms)
Microphone Volume	1	See microphone volume field description
DAC Left Channel Volume	1	See DAC volume field description
DAC Right Channel Volume	1	See DAC volume field description
CRC	4	32-bit CRC check value calculated for all fields

4.2 Input/Output Mode Data Format¶

Field Bit Definitions

Byte	Function Description
BYTE 0-BYTE4	Specific value definitions refer to product specification

4.3 Control Parameter Data Format¶

Restart ReasonPower-up ModeVolume Control ParametersAudio Stream FormatAudio Type

Value	Description
0x00	Power-up restart
0x01	Mode switch restart
0xFF	Other reason restart

Value	Description
0x00	Default mode, use power-up configuration information parameters at startup
0x01	Power-off memory mode, use user configuration parameters obtained from MCU at startup

Microphone Volume

Value	Description
0xFF	Mute
0x00-0xFE	Volume value, specific mapping defined by application

DAC Volume

Value	Description
0x00	Mute
0x01-0xFF	Volume value, specific mapping defined by application

Value	Format	Parameter
0x00	AUDIO_PCM_44100	44.1kHz PCM
0x01	AUDIO_PCM_48000	48kHz PCM
0x02	AUDIO_PCM_88200	88.2kHz PCM
0x03	AUDIO_PCM_96000	96kHz PCM
0x04	AUDIO_PCM_176400	176.4kHz PCM
0x05	AUDIO_PCM_192000	192kHz PCM
0x06	AUDIO_PCM_352800	352.8kHz PCM
0x07	AUDIO_PCM_384000	384kHz PCM
0x08	AUDIO_PCM_705600	705.6kHz PCM
0x09	AUDIO_PCM_768000	768kHz PCM
0x0A	AUDIO_PCM_1441200	1.4112MHz PCM
0x0B	AUDIO_PCM_1536000	1.536MHz PCM
0x0C	AUDIO_PCM_32000	32kHz PCM
0x0D	AUDIO_PCM_64000	64kHz PCM
0x0E	AUDIO_PCM_128000	128kHz PCM
0x0F	AUDIO_PCM_256000	256kHz PCM
0x10	AUDIO_PCM_512000	512kHz PCM
0x11	AUDIO_DSD_64	DSD64
0x12	AUDIO_DSD_128	DSD128
0x13	AUDIO_DSD_256	DSD256
0x14	AUDIO_DSD_512	DSD512
0x15	AUDIO_DSD_1024	DSD1024
0x16	AUDIO_MQA_44100	44.1kHz MQA
0x17	AUDIO_MQA_88200	88.2kHz MQA
0x18	AUDIO_MQA_176400	176.4kHz MQA
0x19	AUDIO_MQA_352800	352.8kHz MQA
0x1A	AUDIO_MQA_705600	705.6kHz MQA
0x1B	AUDIO_MQA_1411200	1.4112MHz MQA
0x1C	AUDIO_MQA_2822400	2.8224MHz MQA
0x1D	AUDIO_MQA_5644800	5.6448MHz MQA
0x1E	AUDIO_MQA_48000	48kHz MQA
0x1F	AUDIO_MQA_96000	96kHz MQA
0x20	AUDIO_MQA_192000	192kHz MQA
0x21	AUDIO_MQA_384000	384kHz MQA
0x22	AUDIO_MQA_768000	768kHz MQA
0x23	AUDIO_MQA_1536000	1.536MHz MQA
0x24	AUDIO_MQA_3072000	3.072MHz MQA
0x25	AUDIO_MQA_6144000	6.144MHz MQA
0xFF	AUDIO_NO_USED	Not used

Value	Type	Description
0x00	PCM	Standard PCM audio
0x01	DoP	Reserved
0x02	MQA	MQA encoded audio
0x03	MQB	MQB encoded audio
0x04	MQA_Studio	MQA Studio encoding
0x05	DSD Native	DSD encoded audio