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Telink Low-power Audio Recording Card Getting Started

Overview

This document helps you quickly complete firmware flashing and functional verification for the recording card example project. The main features of the recording card include real-time recording, file saving and transfer, and OTA (over-the-air) upgrade. The recording card is used in scenarios such as call recording and meeting recording.

The recording card example is organized around the following three scenarios, each of which is independent and can be verified as needed:

Scenario Description
Recording The recording card records audio independently, with files stored locally.
File download/upload Download recorded files to a phone via Bluetooth Low Energy (BLE) or Wi-Fi, or stream recording data in real time via BLE.
Extended features Includes USB mass storage read-only mode (for exporting recordings), OTA upgrade, and noise reduction and VAD

Hardware and software preparation

Hardware list

Hardware type Model/specification Quantity Description
PC Windows 10/11 1 Used as the development host for running programming software, etc.
Development board C1T315A87_V1.2 1 Development board equipped with TL721x and TLSR9118
Programmer Programmer V3 1 Used for flashing firmware to the target chip
Cables Mini-USB cable 1 Connects the PC to the programmer, providing the programming channel
USB Type-C cable 1 Connects the PC to the USB port on the development board
Dupont wires 1 Connects the development board to the programmer
Phone Android (recommended) 1 Runs the test applications TelinkRecordCard and TelinkBootOTA

C1T315A87_V1.2 is a custom development board designed for specific application scenarios. If you require higher audio performance, we offer a range of advanced solutions. Please feel free to contact us for detailed consultation.

The full view of the development board is shown below:

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Functional area description:

Area Function description
USB port ① (upper) Wi-Fi chip firmware download and log output
USB port ② (lower) TL721x USB mass storage function
Reset button TL721x system reset
Key1 function button Single press: Start / stop recording
Double press: TLSR9118 power on / off
Triple press: Enable noise reduction + VAD
Quadruple press: Disable noise reduction + VAD
Long press: Enable / disable USB mass storage mode
Red LED Recording status indicator
Blue LED BLE status indicator
DIP switch Controls communication enable with the Wi-Fi chip
External storage interface Connects to an SD card for storing recording files
Antenna interface Bluetooth/Wi-Fi wireless antenna connection (supports independent or shared antenna)

LED function description:

LED Off Solid on Breathing Slow blink
Red LED Powered off Ready (not recording) Recording in progress -
Blue LED BLE off BLE connected - BLE advertising (not connected)

Antenna connection description:

The development board supports both independent and shared antenna configurations. In independent mode, separate rubber-duck antennas for Bluetooth and Wi-Fi must be connected to the L3 and L4 interfaces respectively. In shared mode, solder 0 Ω resistors at L3 and L4, and connect a single antenna to J2.

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Software and firmware list

Software/firmware Name Description
Programming tool BDT (Burning and Debugging Tool) Dedicated programming software for flashing firmware to the development board.
Pre-built firmware recording_card_application.bin Recording card application firmware, flash address 0x00000000, for functional verification, flashed to TL721x
wifi_app.bin Wi-Fi application firmware, flashed to TLSR9118
wifi_boot.bin Wi-Fi boot firmware, flashed to TLSR9118
recording_card_ota.bin OTA test firmware, needs to be placed on the phone
Test applications telink_record_card.apk Recording card test app, used to demonstrate file download, deletion, and real-time recording
TelinkBootOtaDemo_V0.3.0.apk OTA demonstration app

Note

Click here to download the pre-built firmware and the APK packages of the test software.

Installing BDT

BDT is Telink's dedicated programming and debugging tool, used for flashing firmware onto the development board.

  1. Download: Visit the Telink developer center - development tools and download the appropriate tool package for your operating system.

  2. Extract and run: BDT is a portable application that does not require installation. Simply extract and run. Taking Windows as an example:

    1. Extract to a custom path, for example C:\Telink\BDT.
    2. Navigate to the extracted release directory, for example C:\Telink\BDT\release_v5.9.2.
    3. Double-click Telink BDT.exe to launch the tool.

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  3. Select the programmer version: BDT supports multiple programmer versions; select the appropriate version based on the chip model being used. This document uses Programmer V3:

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Flashing firmware

Note

Firmware must be flashed in the order of TL721x first, then TLSR9118. This order cannot be reversed. Select the corresponding target chip during the flashing process based on the actual device being programmed.

Flashing TL721x firmware

Connecting hardware

Connect the PC, programmer, and development board as follows:

  • PC ↔ Programmer: Connect using a Mini-USB cable. A solid green LED on the programmer indicates that the PC has successfully recognized the programmer.

  • Programmer ↔ Development board: Connect using Dupont wires:

    • Power lines: VCC ↔ VCC; GND ↔ GND
    • Data line: SWM ↔ SWS (Swire)

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Flashing firmware

  1. Connect the device Before flashing firmware, ensure that BDT has detected the programmer, as shown below.

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    • If BDT does not find the device, click Device → Refresh to refresh the device list.
    • If BDT discovers multiple devices, all devices will be listed. The first device is activated by default; you can also manually switch the target device in the list.

  2. Configuration and flashing

    1. Select the target chip model. From the chip drop-down menu at the top, select TL721x.
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    2. Select the download mode as EVK.
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    3. Set the flash address: Click the Setting button to open the configuration window, then switch to the Flash tab. In the Download Addr field, set the firmware start offset address. The default value is 0x000000.
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    4. Load the firmware file: Click File → Open/Reopen in the menu bar, and select the recording_card_application.bin firmware. After successful loading, the full file path is displayed at the bottom of the main interface.
      0Xlr1qyBmJ2ACk.png h8DwTTgi7lgFIxNP.png

    5. Check the connection status between the development board and the PC:

      • When connected properly, evk device: ok is displayed in the lower-left corner of the main interface.
      • When the development board is not properly connected, usb device: not found is displayed in the lower-left corner.
        RWvg-AUAQbX4ZYYN.png

    6. Disable Flash write protection: Click the Unlock button or check the auto unlock option. Download will fail if Flash is in a write-protected state.
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    7. Flash the firmware: First click Activate to activate the development board, then click the Download button. Wait for the log window to indicate successful flashing.
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    8. Reset and run: Before flashing, set the reset mode to auto mode; after flashing completes, the chip will automatically reset and run. If manual mode is selected, click the Reset button to manually reset after flashing.
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Flashing TLSR9118 firmware

Connecting hardware

Connect the PC and development board as follows:

  • PC ↔ Development board: Use a USB Type-C cable to connect USB port ① on the development board to the PC. Successful connection is indicated when the device is recognized as a serial port.

Note

Before flashing, you must double-press Key1 to power on the TLSR9118.

Flashing firmware

  1. From the chip drop-down menu at the top, select the target chip 9118.
  2. Open Tool, and in the EMI Tool, open the firmware save path under Firmware, then select wifi_app.bin and wifi_boot.bin. 4UJDkdWFw2v4dVRX.png

  3. Select the corresponding serial port; the default baud rate is 2000000. Click Download; the device will automatically reset after the download completes.

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Note

First-time users must click Install Uart driver X64 to install the device driver.

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Functional verification

After flashing is complete, reset the development board. The red LED turns solid on (ready state) and the blue LED starts slow blinking (BLE advertising state). If there is no operation within 30 seconds, the device enters sleep mode (both red and blue LEDs turn off). Single-press Key1 to wake up the device (red LED solid on, blue LED slow blinking).

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Verification scenario 1: Recording

The recording card records audio independently, with files stored locally.

Operation steps:

  1. Single-press Key1 to start recording; the red LED enters breathing mode.
  2. Single-press Key1 again to stop recording; the red LED returns to solid on (ready state).

Verification criteria:

  • The red LED breathes continuously during recording and returns to solid on after stopping;
  • Button operations and LED state changes match the table below:
Operation Red LED state Meaning
Single-press Key1 (start recording) Breathing Recording in progress
Single-press Key1 again (stop recording) Solid on Ready (not recording)

Verification scenario 2: File download/upload

Download recorded files to a phone via BLE or Wi-Fi, or stream recording data in real time.

Installing the test application

The following features are available through the TelinkRecordCard app:

Feature Description
Opus Decoder The app controls the recording card to start recording; recording data is streamed to the app in real time via BLE, where the app performs Opus decoding and saves it as a local file
File Transfer Reads the recording card file list via BLE or Wi-Fi connection, supports downloading files to the phone
Timer Sync The app performs system time synchronization calibration for the recording card via the BLE channel
  1. Download the telink_record_card.apk installation package to your phone (no specific installation path required).

  2. After installation, open the app, enter the SETTING interface, and switch between the features listed above to try them out:

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Connecting to the recording card

Before establishing a BLE connection between TelinkRecordCard and the recording card, prepare the device as shown in the figure below:

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  1. Power on the recording card. After the device starts, it begins BLE advertising by default, with the default advertising name Xyris.

  2. Open the TelinkRecordCard app, switch to the ADV interface, set filtering conditions as needed (supports filtering by device name or MAC address), then click Refresh to scan and select the target device to complete connection.

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Real-time recording data streaming (Opus Decoder)

Real-time recording operation flow on the app: Tap Start to begin recording, tap Stop to end recording; real-time playback is supported during recording. After stopping, tap Save to save the file. Locate the recording file using the save path shown in the interface to play back and test the recording quality.

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Downloading recording files via BLE (File Transfer)

  1. Enter the SETTING interface and switch to the File Transfer feature.

  2. Go to the ADV interface and select "Xyris" to establish a BLE connection. After a successful connection, the app automatically retrieves the recording card file list; files can be renamed, deleted, or downloaded.

    Note

    If a BLE connection cannot be established, first check whether the development board is in sleep mode. If it is, single-press Key1 to wake the device and try again.

Downloaded files are saved on the phone in the TelinkRecordCard/files_Xyris_XXXXXXXXXXXX directory, where XXXXXXXXXXXX represents the LE MAC address of the current device.

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Downloading recording files via Wi-Fi

When recording files are large, BLE transfer rates are limited. It is recommended to switch to the Wi-Fi channel for downloading.

Prerequisites:

Before using the Wi-Fi download feature, set the DIP switch on the development board as shown below to enable Wi-Fi communication.

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Operation steps:

  1. Set the DIP switch to the corresponding position according to the schematic diagram, ensuring the Wi-Fi chip (TLSR9118) is properly powered and communication is enabled;
  2. Power on the recording card and wait for the device to start up completely;
  3. Open TelinkRecordCard and switch to the File Transfer feature interface;

  4. During file download, tap CHANGE TO WIFI; after the Wi-Fi connection succeeds, the remaining files will continue downloading.

    b45zIp8HX87z9hBP.png

Wi-Fi connection troubleshooting:

If Wi-Fi does not exist is prompted or the connection fails when switching to Wi-Fi, troubleshoot by checking the following possible causes:

Possible cause Solution
Wi-Fi is already connected to another phone (this Wi-Fi supports only one phone connection at a time) Restart Wi-Fi, or disconnect the phone that is already connected
The phone app has not obtained the Wi-Fi information from the phone system First check whether the Wi-Fi appears in the phone's system Wi-Fi settings
DIP switch not set to the correct position; Wi-Fi chip power or communication is abnormal Re-set the DIP switch according to the schematic diagram and confirm power supply is normal
Antenna not properly connected, causing unstable signal Confirm the antenna is correctly connected to the development board

Wi-Fi and BLE are two independent transmission channels and can be flexibly switched according to actual usage scenarios.

Verification scenario 3: Extended features

USB mass storage read-only mode (exporting recordings)

The recording card supports USB mass storage read-only mode. Connect the PC and development board as follows:

  • PC ↔ Development board: Use a USB Type-C cable to connect USB port ② on the development board to the PC.

Note

Ensure sufficient power supply when verifying the USB mass storage function. If power is insufficient, you can connect both USB port ① and USB port ② simultaneously for power supply.

USB mass storage mode is disabled by default; long-press Key1 to enable it. USB mass storage mode is mutually exclusive with recording and file transfer: USB mass storage mode cannot be enabled while recording or file transfer is in progress; after USB mass storage mode is enabled, recording and file operation requests will be rejected.

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OTA upgrade

The TelinkBootOTA app can be used to verify OTA wireless firmware upgrades for the recording card.

Installing the test application
  1. Download the OTA firmware: Download recording_card_ota.bin to your phone; no specific storage path is required, as long as it can be located during the upgrade. (This is the firmware that will be selected in the app during the upgrade.)
  2. Download and install the app: Download the TelinkBootOtaDemo_V0.3.0.apk installation package to your phone and complete installation. The installation package and firmware file do not need to be stored in the same directory.

The TelinkBootOTA app for the Android platform is provided together with the firmware; iOS users can download and install it from the App Store. Regardless of how the app is obtained, the recording_card_ota.bin firmware required for the upgrade must be manually imported to the phone.

Connecting to the recording card
  1. Open the TelinkBootOTA app, enter the ADV interface, and tap Refresh to scan for devices.
  2. Select the corresponding recording card from the list to complete connection.

Note

If no device is found after refreshing, check whether the development board is in sleep mode. If it is, single-press Key1 to wake the device and try again.

OTA upgrade
  1. Select firmware: After a successful connection, tap Bin file path and select the downloaded recording_card_ota.bin file from the phone's storage.
  2. Start upgrade: Tap Start; the app will begin transferring the firmware and performing the upgrade. Wait for the firmware transfer to complete; the development board will automatically restart and the upgrade is complete.

Noise reduction and VAD

The recording card integrates two Telink-developed audio algorithms. They deliver low latency and efficient use of computing power, significantly improving recording quality, and are well suited to scenarios such as TWS earbuds, conferencing systems, and in-vehicle voice interaction:

  • NN-NS (NN-based Noise Suppression): A neural-network-based noise reduction algorithm. When enabled, it filters ambient noise and background noise in real time, improving the signal-to-noise ratio (SNR) by up to 30 dB while preserving the naturalness and clarity of speech.
  • VAD (Voice Activity Detection): Accurately locates the start and end points of speech in noisy audio and separates silence from actual speech, saving computing power, storage, and bandwidth during silent periods.

Operation steps:

  1. Triple-press Key1 to enable noise reduction + VAD, filtering ambient noise and background noise.
  2. Quadruple-press Key1 to disable noise reduction + VAD.

FAQ

TL721x flashing failure

  • Possible cause: The development board has not been activated (Activate) or unlocked (Unlock); the chip is in a protected state and cannot receive programming commands.
  • Solution: Before clicking Download, click Activate to activate the chip. After Activate MCU ok is displayed, click Download to flash.

Community and resources

Resource Description
Telink official forum Technical exchange and support
Telink official website Product center
Telink documentation website Documentation center