phaten-audio/en/docs/dev_doc/protocols/xu316_zerocode_protocol.md

---
title: XU316 USB HiFi Decoder Zero-Code Product Configuration Protocol
status: new
description: XU316 USB HiFi Decoder Zero-Code Product Configuration Protocol Documentation
authors:
  - admin
tags:
  - Protocol
  - XU316
  - USB Audio
  - UART
search:
  boost: 2
---

# XU316 USB HiFi Decoder Zero-Code Product Configuration Protocol

--8<-- "common/phaten_xmos_support_img.md"

## Protocol Overview :material-file-document-outline:

!!! abstract "Functional Positioning and Scope"
    This document provides a detailed description of the configuration protocol for communication between the XU316 USB HiFi decoder zero-code product and MCU via UART. The protocol offers a complete functional set for audio device configuration, status monitoring, and media control.


## I. Protocol Basic Specification :material-connection:

### 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

!!! example "Generic Frame Format"
    All commands and responses follow this frame format:

    | Field | Bytes | Description |
    |:----------:|:--------:|:-----------------------------------------:|
    | Frame Header | 2 | Fixed as 0x55aa |
    | Version | 1 | Protocol version number |
    | Command | 1 | Indicates frame function |
    | Data Length | 1 | Length N of subsequent data, excluding final checksum byte |
    | Data | N | Actual data content |
    | Checksum | 1 | Byte-wise sum from frame header, modulo 256 |

!!! warning "Data Transmission Notes"
    All multi-byte data uses **big-endian** transmission. Example data in protocol is shown in hexadecimal.

### 1.3 Communication Mechanism

#### 1.3.1 Acknowledgment Mechanism

!!! tip "Acknowledgment and Timeout Handling"
    - All commands require acknowledgment from the receiver
    - Default command timeout is 300ms, timeout results in communication failure
    - Special commands may have different timeout values, specified in respective command descriptions

#### 1.3.2 Retry and Fault Tolerance Mechanism

```mermaid
flowchart TD
    A[Send Command] --> B{Wait for Response}
    B -->|Timeout| C[Resend 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 :material-power-plug:

### 2.1 Startup Interaction Flow

```mermaid
sequenceDiagram
    participant XU316
    participant MCU
    participant Flash

    rect
        Note over XU316,Flash: System Loader Firmware


        rect
            Note over XU316,MCU: Power-On Startup Phase
            XU316->>MCU: Send Startup Command (0x00)
            Note over XU316:
            alt Timeout without response (max 4 attempts, enters USB->I2S mode if all fail)
                XU316->>MCU: Resend 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 excludes 0x01 (no basic product info update)
                XU316->>Flash: Read Basic Product Info
                Flash-->>XU316: Return Basic Product Info
            else Startup option includes 0x01 (update basic product info) or Flash data incomplete
                XU316->>MCU: Send Read Basic Product Info Command (0x01)
                MCU-->>XU316: Return New Basic Product Info
                XU316->>Flash: Save Configuration
            end
        end

        rect
            Note over XU316,Flash: Power-On Configuration Phase
            alt Startup option excludes 0x02 (no power-on config update)
                XU316->>Flash: Read Power-On Config
                Flash-->>XU316: Return Power-On Config Data
            else Startup option includes 0x02 (update power-on config) or Flash data incomplete
                XU316->>MCU: Send Get Power-On Config Command (0x02)
                MCU-->>XU316: Return New Power-On Config
                XU316->>Flash: Save New Power-On Config
            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 Config Command (0x04)
        MCU-->>XU316: Return Current User Config
        Note over XU316: Initialize APP and apply current user config
        XU316->>MCU: Send Startup Complete Command (0x05)
        MCU-->>XU316: Return Complete Command Response
        par Parallel Processing
            loop Status Reporting
                XU316->>MCU: Send on status change or 15s timer
            end
            loop Business Processing
                MCU->>XU316: Send business commands
                XU316-->>MCU: Respond to business commands
            end
        end
    end
```

### 2.2 Detailed Startup Flow Description

=== "Power-On Startup and Option Phase"
    1. XU316 sends startup command (command 0x00) to MCU upon power-on, containing:
        - UAC1.0 VID/PID
        - UAC2.0 VID/PID
        - Basic info CRC
        - Power-on config info CRC
    2. MCU receives startup command, checks if info needs update, sends response
    3. XU316 waits for MCU response
    4. If timeout without response, XU316 resends startup command up to 4 times
    5. If still no response, loads default USB configuration and enumerates USB
    6. If normal response received, XU316 parses startup options

=== "Basic Information Update Phase"
    **Execution Condition**: Startup option includes 0x01 (update basic product info)

    **Steps**:

    1. XU316 sends 0x01 command to request basic product info
    2. MCU returns new basic product info to XU316
    3. XU316 updates and saves config to internal storage

=== "Power-On Configuration Phase"
    **Execution Condition**: Startup option includes 0x02 (update power-on config) or Flash data incomplete

    **Steps**:

    1. XU316 sends 0x02 command to request power-on config
    2. MCU returns new power-on config to XU316
    3. XU316 updates and saves config to internal storage

=== "Application Firmware Loading Phase"

    **Steps**:

    1. XU316 sends 0x03 command to get current input/output mode
    2. MCU returns current mode info to XU316
    3. XU316 loads corresponding input/output mode based on returned mode

=== "Application Initialization Phase"
    **Steps**:

    1. XU316 sends 0x04 command to get current user config
    2. MCU returns current user config to XU316
    3. XU316 initializes application and applies relevant config
    4. XU316 sends 0x05 command to indicate startup complete
    5. MCU returns acknowledgment response

## III. Protocol Command Set :material-console:

### 3.1 Command Classification Overview

=== "Startup and Basic Commands (0x00-0x0F)"
    | Command | Command Description | Direction |
    |:--------:|:---------------------------------------------|:----------:|
    | 0x00 | Startup | XU316→MCU |
    | 0x01 | Read Product Info | XU316→MCU |
    | 0x02 | Read Power-On Config | XU316→MCU |
    | 0x03 | Get Current Input/Output Mode | XU316→MCU |
    | 0x04 | Get Current User Config | XU316→MCU |
    | 0x05 | Startup Complete | XU316→MCU |

=== "Business Control Commands (0x20-0x2F)"
    | Command | 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 |

=== "HID-MCU Transparent Transmission Commands (0xEE-0xEF)"
    | Command | Command Description | Direction |
    |:--------:|:---------------------------------------------|:----------:|
    | 0xEE | HID-initiated transparent transmission to MCU via XU316 | XU316→MCU |


=== "DAC Control Commands (0xF0-0xFF)"
    | Command | Command Description | Direction |
    |:--------:|:---------------------------------------------|:----------:|
    | 0xF0 | DAC Configuration Selection | MCU→XU316 |

!!! note "Command Usage Instructions"
    1. All commands must follow basic frame format specification
    2. Each command requires acknowledgment from receiver to be considered successful
    3. Business control commands (0x20 and above) can only be used after device startup completion

### 3.2 Basic Function Command Details

#### 3.2.1 Startup (0x00)

=== "Command Format"
    **XU316 Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x00
    Data Length:     1 byte  - 17
    Data:            17 bytes
                     B0:     Restart reason (0x00 power-on, 0x01 mode switch, 0xFF other)
                     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 info 32-bit CRC
                     B13-16: Power-on config info 32-bit CRC
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **MCU Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x00
    Data Length:     1 byte  - 0x1
    Data:            1 byte
                     B0: Startup options
                         0x00 Use all default info
                         0x01 Need to update basic product info
                         0x02 Need to update power-on config
                         0x04 Need to update other config
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    1. This command is sent first by XU316 upon power-on or restart to inform MCU that device has started
    2. XU316 sends current stored product info CRC and config info CRC to MCU
    3. MCU compares CRC to determine if XU316 config info needs update
    4. MCU uses startup option field in response to inform XU316 of subsequent operations

=== "Usage Flow"
    ```mermaid
    flowchart TB
        A[XU316 Startup] -->B[Send 0x00 Command]
        B -->C{MCU Response}
        C -->|Timeout| D[Resend Command]
        D -->E{Retry Count<4?}
        E -->|Yes| C
        E -->|No| F[Use Default Config]
        C -->|Normal Response| G[Parse Startup Options]
        G -->|0x01| H[Update Basic Product Info]
        G -->|0x02| I[Update Power-On Config]
        G -->|0x04| J[Update Other Config]
        G -->|0x00| K[Continue Startup Flow]
    ```

=== "Notes"
    * If MCU has no response, XU316 will use stored default config to continue startup
    * Restart reason field can be used by MCU to identify specific reason for XU316 restart for different handling
    * When multiple items need update, MCU can combine multiple options via bitwise operations

#### 3.2.2 Read Product Info (0x01)

=== "Command Format"
    **XU316 Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x01
    Data Length:     1 byte  - 0x00
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **MCU Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x01
    Data Length:     1 byte  - 0x3C (60 bytes)
    Data:            60 bytes - Product basic info, see data field description
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used by XU316 to get product basic info such as VID/PID, product name, etc.
    - Execution condition: Startup option includes 0x01 flag or product info CRC mismatch
    - XU316 updates internal stored product basic info after receiving this info

=== "Data Structure"
    Product basic info 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 checksum)
    ```

#### 3.2.3 Read Power-On Config (0x02)

=== "Command Format"
    **XU316 Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x02
    Data Length:     1 byte  - 0x00
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **MCU Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x02
    Data Length:     1 byte  - 0x0E (14 bytes)
    Data:            14 bytes - Power-on config info, see Section 4.1
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used by XU316 to get initial power-on config info
    - Execution condition: Startup option includes 0x02 flag or power-on config CRC mismatch
    - XU316 sets default input/output mode, volume, and other parameters based on this config info

=== "Data Structure"
    Power-on config info data structure (14 bytes):
    ```
    Default Input/Output Mode:     5 bytes
    Mute Duration:                 2 bytes (0-65535ms)
    Microphone Default Volume:     1 byte
    DAC Left Channel Default Vol:  1 byte
    DAC Right Channel Default Vol: 1 byte
    CRC:                           4 bytes (32-bit CRC checksum)
    ```

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

=== "Command Format"
    **XU316 Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x03
    Data Length:     1 byte  - 0x00
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **MCU Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x03
    Data Length:     1 byte  - 0x05 (5 bytes)
    Data:            5 bytes - Input/output mode, see data field section
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used by XU316 during startup to query current input/output mode to enable
    - XU316 loads corresponding application firmware based on returned mode
    - This command is used for mode matching and confirmation during device startup

#### 3.2.5 Get Current User Config (0x04)

=== "Command Format"
    **XU316 Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x04
    Data Length:     1 byte  - 0x00
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **MCU Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x04
    Data Length:     1 byte  - 0xE (14 bytes)
    Data:            14 bytes - User config parameters, see Section 4.1
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used by XU316 to get current user-selected volume, mode, and other config
    - Executed after application firmware loading and before application startup
    - Application initializes corresponding parameters based on returned info

#### 3.2.6 Startup Complete (0x05)

=== "Command Format"
    **XU316 Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x05
    Data Length:     1 byte  - N
    Data:            N bytes
                     B0: Startup status (0 success, 1 mode mismatch, other values failure)
                     B1-BN: Application runtime parameters, see Section 4.1
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **MCU Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x05
    Data Length:     1 byte  - 0x00
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command indicates XU316 startup flow is complete and ready to begin normal operation
    - Contains startup status info to inform MCU if startup succeeded or encountered problems
    - All subsequent business commands can only be used after this command is sent successfully

### 3.3 Business Control Command Details

!!! warning "Usage Prerequisites"
    The following commands can only be used after XU316 startup completion (after sending 0x05 command and receiving response)

#### 3.3.1 Report Application Status (0x20)

=== "Command Format"
    **XU316 Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x20
    Data Length:     1 byte  - N
    Data:            N bytes - Application runtime parameters, see Section 4.1
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **MCU Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x20
    Data Length:     1 byte  - 0x00
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used by XU316 to report current application status to MCU
    - Typically sent when status changes, such as volume change, mode switch, etc.
    - MCU can update UI display or adjust related functions based on this info

#### 3.3.2 Media Control (0x21)

=== "Command Format"
    **MCU Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x21
    Data Length:     1 byte  - 0x01 (1 byte)
    Data:            1 byte  - Media control command
                     0x00 Volume Up / Vol Up
                     0x01 Volume Down / 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  - Byte-wise sum from frame header, modulo 256
    ```

    **XU316 Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x21
    Data Length:     1 byte  - 0x00
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used by MCU to send media control commands to XU316
    - XU316 converts received commands to corresponding HID commands and sends to PC
    - Suitable for implementing remote control or physical button media playback control

=== "Control Key Mapping Table"
    | Control Code | Function | USB HID Usage |
    |:-----:|:------------------:|:------------------:|
    | 0x00 | Volume Up | Increase system volume |
    | 0x01 | Volume Down | Decrease system volume |
    | 0x02 | Play/Pause | Control media playback state |
    | 0x03 | Next Track | Switch to next track |
    | 0x04 | Previous Track | Switch to previous track |
    | 0x05 | Fast Forward | Fast forward in current track |
    | 0x06 | Rewind | Rewind in current track |
    | 0x07 | Mute | Toggle system mute state |

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

=== "Command Format"
    **XU316 Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x22
    Data Length:     1 byte  - 0x02 (2 bytes)
    Data:            2 bytes - Audio stream format and type, see audio stream format and type field
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **MCU Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x22
    Data Length:     1 byte  - 0x00
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used by XU316 to report current audio stream format and type to MCU
    - Typically sent when playback starts or format changes
    - MCU can update display based on this info, such as displaying PCM/DSD/MQA/DOP status

#### 3.3.4 Set Input/Output Mode (0x23)

=== "Command Format"
    **MCU Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x23
    Data Length:     1 byte  - 0x05 (5 bytes)
    Data:            5 bytes - Input/output mode, see input/output mode field
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **XU316 Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x23
    Data Length:     1 byte  - 0x00
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used by MCU to request XU316 to switch to specific input/output mode
    - Typically triggered by user operation, such as pressing mode selection button
    - XU316 may need to restart to load new mode firmware

#### 3.3.5 Send Playback Volume (0x24)

=== "Command Format"
    **MCU Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x24
    Data Length:     1 byte  - 0x02 (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  - Byte-wise sum from frame header, modulo 256
    ```

    **XU316 Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x24
    Data Length:     1 byte  - 0x00
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used by MCU to set current playback volume to XU316


#### 3.3.6 Send Recording Volume (0x25)

=== "Command Format"
    **MCU Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x25
    Data Length:     1 byte  - 0x01 (1 byte)
    Data:            1 byte  - 0xFF Mute, 0-0dB -127: -127dB
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **XU316 Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x25
    Data Length:     1 byte  - 0x00
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used by MCU to set current microphone recording volume to XU316

#### 3.3.7 Switch MCLK (0x26)

=== "Command Format"
    **MCU Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x26
    Data Length:     1 byte  - 1
    Data:            1 byte  - 0: Internal MCLK, 1: External MCLK
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **XU316 Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x26
    Data Length:     1 byte  - 0
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used by XU316 to control master clock source switching
    - Can switch between internal clock or external clock
    - Important for certain audio applications requiring precise synchronization

#### 3.3.8 Set Unmute (0x27)

=== "Command Format"
    **MCU Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x27
    Data Length:     1 byte  - 2
    Data:            2 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **XU316 Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x27
    Data Length:     1 byte  - 0
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - DAC unmute time delay during mode switching, unit is milliseconds

#### 3.3.9 Send Audio Format Time Delay (0x28)

=== "Command Format"
    **MCU Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0x28
    Data Length:     1 byte  - 2
    Data:            2 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **XU316 Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0x28
    Data Length:     1 byte  - 0
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - Send audio format time delay

#### 3.3.10 Get Firmware Version (0xF1)

=== "Command Format"
    **MCU Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0xF1
    Data Length:     1 byte  - 2
    Data:            2 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **XU316 Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0xF1
    Data Length:     1 byte  - 0
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - Get firmware version


### 3.4 DAC Configuration Selection (0xF0)

=== "Command Format"

    **MCU Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0xF0
    Data Length:     1 byte  - 4
    Data:            4 bytes
                     Byte 0: 0: Enable I2C DAC configuration  1: Disable I2C DAC configuration
                     Byte 1 - 3: reserved
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **XU316 Returns**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0xF0
    Data Length:     1 byte  - 0
    Data:            0 bytes
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - Test command for MCU to set DAC configuration selection to XU316. Let XU316 configure DAC through DAC I2C or MCU configure DAC itself
    - This command is product-specific and not supported by all products. Refer to product specification for specific support details.

### 3.5 HID and MCU Transparent Data Transmission Commands via XU316

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

=== "Command Format"

    **XU316 Sends**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x00
    Command:         1 byte  - 0xEE
    Data Length:     1 byte  - 0x39 (57 bytes), due to HID protocol limitation, data length must be 57 bytes
    Data:            57 bytes - Due to HID protocol limitation, must be 57 bytes transparent data
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

    **MCU Returns (can return multiple frames)**
    ```
    Frame Header:    2 bytes - 0x55aa
    Version:         1 byte  - 0x03
    Command:         1 byte  - 0xEE
    Data Length:     1 byte  - 0x39 (57 bytes), due to HID protocol limitation, data length must be 57 bytes
    Data:            57 bytes - Due to HID protocol limitation, must be 57 bytes transparent data
    Checksum:        1 byte  - Byte-wise sum from frame header, modulo 256
    ```

=== "Function Description"
    - This command is used for HID-initiated transparent data transmission to MCU via XU316
    - Typically transparent data is MCU OTA data or MCU data reply to HID



## IV. Data Structure Definition :material-database:

### 4.1 Product Configuration Data Structure

=== "1. Product Basic Info"
    | 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 Manufacturer 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 checksum calculated over all fields                        |

    !!! tip "CRC Usage Instructions"
        MCU can determine whether basic product info needs update based on CRC value returned by XU316. When CRC mismatch occurs, complete basic product info should be sent.

=== "2. Power-On Config Info"
    | Field                    | Bytes | Description                                          |
    |-------------------------|--------|-----------------------------------------------|
    | **Default Input/Output Mode**        | 5      | See input/output mode field description                           |
    | **Mute Duration**            | 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 checksum calculated over all fields              |

=== "3. Application Runtime Parameters"
    | Field | Bytes | Description |
    |-------------------------|--------|-----------------------------------------------|
    | **Input/Output Mode** | 5 | See input/output mode field description |
    | **Mute Duration** | 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 checksum calculated over all fields |

=== "4. User Config Parameters"
    | Field | Bytes | Description |
    |-------------------------|--------|-----------------------------------------------|
    | **Input/Output Mode** | 5 | See input/output mode field description |
    | **Mute Duration** | 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 checksum calculated over all fields |

### 4.2 Input/Output Mode Data Format

=== "Field Bit Definition"

    | Byte |  Function Description |
    |-----|-----------------------------------------------|
    | BYTE 0-BYTE4 | Specific values defined in product specification |


### 4.3 Control Parameter Data Format

=== "Restart Reason"
    | Value | Description |
    |-------|-------------------------------|
    | 0x00 | Power-on restart |
    | 0x01 | Mode switch restart |
    | 0xFF | Other reason restart |

=== "Power-On Mode"
    | Value | Description |
    |-------|------------------------------------------------------------|
    | 0x00 | Default mode, use power-on config info parameters at startup |
    | 0x01 | Power-off memory mode, use user config parameters from MCU at startup |

=== "Volume Control Parameters"

    **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 |

=== "Audio Stream Format"
    | Value | Format | Parameters |
    |-------|-------------------|-----------------|
    | 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 |

=== "Audio Type"
    | 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 encoded |
    | 0x05 | DSD Native | DSD encoded audio |


## V. Consultation and Feedback
<details>
<summary>Click to expand consultation and feedback form</summary>

--8<-- "common/customer_form.md"

</details>