Reference
Last revision 2025/12/19
This article presents a detailed reference guide for AT commands, covering communication protocols, volume control, playback modes, Bluetooth audio, BLE settings, and more, enabling users to efficiently manage and optimize their devices through precise command usage.
Communication Protocol Description
AT Command List
Note:
- "\r\n is" omitted in all the commands below, and you need to add it to the end of the command in actual use. For example "AT+VOL=5\r\n", designate volume to "5".
- Default serial baud rate: 115200
Volume Command
Control
| Command | Function | Description |
|---|---|---|
| AT+CA05 | Designate volume to "5" | Volume Degree: 00-30 |
| AT+CE | Increase volume | |
| AT+CF | Decrease volume | |
| AT+CU00 | Unmute | |
| AT+CU01 | Mute | |
| AT+CU02 | Mute & Unmute Switch | |
| AT+CS00 | Disable DAC | DAC output high impedance |
| AT+CS01 | Enable DAC | DAC is playing normally |
Query
| Command | Function | Description |
|---|---|---|
| AT+QA | Query the volume of current device | Return “QA+30”, represent the host volume is 30 |
Working Mode Command
Control
| Command | Function | Description |
|---|---|---|
| AT+CM01 | Bluetooth playback mode | |
| AT+CM02 | "U-disk" playback mode | If there is no U-disk, return error information, and do nothing |
| AT+CM03 | "TF-card" playback mode | If there is no TF-card, return error information, and do nothing |
| AT+CM08 | Idle mode | Release all sources, in waiting status |
Query
| Command | Function | Description |
|---|---|---|
| AT+QM | Query the working mode of current device | Return “QM+01”, means it is in “Bluetooth playback mode” 01-Bluetooth；02-U-disk play mode；03-TF card play mode；09-idle |
TF-card or U-disk Command
Control
| Command | Function | Description |
|---|---|---|
| AT+AA00 | Stop | |
| AT+AA01 | Play | |
| AT+AA02 | Pause | |
| AT+AA03 | Play&pause switch | |
| AT+CC | Next | |
| AT+CD | Last | |
| AT+AA04 | Fast forward | |
| AT+AA05 | Fast backward | |
| AT+AA06 | Play next file | |
| AT+AA07 | Play last file | |
| AT+AA08 | Delete the currently playing file | |
| AT+AB15 | Play the 15th file of the device | Refer to the order that the file is copied into the device |
| AT+AF/MY_MUSIC/*.??? | Repeat song in the specified file | Repeat song in the specified file folder “MY_MUSIC” （* for wildcard, ??? for all files） |
| AT+AF/MY_MUSIC/test.mp3 | Play song in the specified file once | Play the file test.mp3 in file folder MY_MUSIC once (Can use wildcard) |
| AT+AC00 | Repeat all | When both U-disk and TF-card are there, repeat all files in the two devices |
| AT+AC01 | Repeat songs in one device | |
| AT+AC02 | Repeat one song | |
| AT+AC03 | Play songs randomly in one device | |
| AT+AC04 | Repeat songs in file folder | If the currently playing song is in the current folder, repeat songs in this folder, otherwise, invalid |
Query
| Command | Function | Description |
|---|---|---|
| AT+M1 | Query the physical serial number of the currently playing file in device | Return“M1+000002”，means the serial number of the currently playing file is 2 |
| AT+M2 | Query the total number of files in the current device | Return “M2+000010”, means the current device has 10 files in total |
| AT+MC | Query the current play mode | Return “MC+00”, means repeat all 00-repeat all; 01-repeat songs in one device; 02-repeat one song; 03-play songs randomly in one device;04-repeat songs in a folder |
| AT+MD | Query the currently playing device | Return “MD+01”, means it is playing the song in the U-disk |
| AT+MF | Query the currently playing file name | Return “MF+test.mp3”, means the currently playing file name is “test.mp3” |
| AT+MP | Query the currently playing status | Return “MP+01”, means it is playing now 00-stop；01-playing；02-pause |
| AT+MT | Query the length of the currently playing file | Return “MT+0000001D”, means the length of the currently playing file is 0x1Ds |
| AT+MK | How long has the current file been playing? | Return “MK+00000000”, the current file has been playing for 0 second |
| AT+MV | Query the current online device | Return “MV+04”, TF-card is online 00-both are not online; 01-U-disk is online; 02-TF card is online; 03-both are online |
| AT+MU | Device plug in/out message | Return “MU+03”, means TF-card plug in 01-U-disk plug out; 02-U-disk plug in;03-TF card plug in; 04-TF plug out |
Bluetooth Audio Command
Control
| Command | Function |
|---|---|
| AT+CB | Play & Pause |
| AT+CC | Next |
| AT+CD | Last |
| AT+BT10086 | Dial “10086” |
| AT+BA00 | Dial back last phone number |
| AT+BA01 | Disconnect Bluetooth |
| AT+BA02 | Refuse to answer |
| AT+BA03 | Hang up |
| AT+BA04 | Answer |
Query
| Command | Function | Description |
|---|---|---|
| AT+TS | Query EDR status | Return “TS+00”, means wait for pairing 00-wait for pairing; 01-Connected, idle; 02-Playing music now; 03-Incoming call not answered; 04-On the phone |
| AT+TT | Query Bluetooth incoming call phone number(return automatically, once every 2s) | Return “TT+10086”, means the incoming number is 10086 |
BLE Command
Control
| Command | Function |
|---|---|
| AT+U0F000 | Designate service UUID as F000 |
| AT+U0F001 | Designate attribute code 1 as F001, “write” +“monitoring” |
| AT+U0F002 | Designate attribute code 2 as F002, “write” +“monitoring” |
| AT+U0F003 | Designate attribute code 3 as F003, “write”, send AT command from phone to control Bluetooth chip |
BLE Query
| Command | Function | Description |
|---|---|---|
| AT+TL | Query BLE Status(auto-return) | Return “TS+01”, means in idle state 00-Not connected; 01-Idle; 02-Broadcast; 03-Connected; 04-Disconnect; 05-Monitoring enabled; 06-Scanning(host); 07-Scanned(host) |
| AT+T6 | Query service UUID | |
| AT+T7 | Query attribute code 1 | |
| AT+T8 | Query attribute code 2 | |
| AT+T9 | Query attribute code 3 |
Setting Command
Control
Most of the settings will take effect when repowering on the module.
Common Setting
| Command | Function | Description |
|---|---|---|
| AT+CT05 | Set baud rate to 115200 | Parameter: 01-06(9600, 19200, 38400, 57600, 115200, 25600) |
| AT+CZ | Reset | Software reset |
| AT+CW | Restore factory settings | Restore factory settings, clear all the previous parameters |
| AT+CN01 | Turn on hint tone | Play the tone when powering on or switching mode |
| AT+CN00 | Turn off hint tone | |
| AT+CJ01 | Enable trigger playing | Stop when completed |
| AT+CJ00 | Disable trigger playing | |
| AT+CP00 | Enter Bluetooth mode when powered on | |
| AT+CP01 | Enter idle mode when powered on | Users need to send mode command |
| AT+CP02 | Auto judge when powered on | Play song in device if there is one, otherwise, enter bluetooth |
| AT+CR01 | Enable auto-return function of key informatin | Key information will return back automatically (Bluetooth status,every 0.5S, TF-card or U-disk, every 1S), for example: incoming call inforamtion |
| AT+CR00 | Disable auto-return function of key information | |
| AT+BDAUDIO | Set Bluetooth name | Set bluetooth name as “AUDIO” |
| AT+BE0000 | Set Bluetooth connection password | Set Bluetooth connection password as “0000” |
| AT+BMDFROBOT | Set BLE Bluetooth name | Set BLE Bluetooth name as “DFROBOT” |
| AT+B101 | Enable pair password | |
| AT+B100 | Disable pair password | Password is not required for next connection |
| AT+C401 | Enable reconnect when powered on | Auto connect the last paired device when powered on |
| AT+C400 | Disable reconnect when powered on | |
| AT+C201 | Enable information auto return | Auto return information when powered on or switching status |
| AT+C200 | Disable information auto return | Chip returns information only when query actively; the chip will not return "OK" when sending control command |
| AT+C101 | Enable AD key | PA5 needs to pull up 22K |
| AT+C100 | Disable AD key |
Uncommon Setting
| Command | Function | Description |
|---|---|---|
| AT+CK01 | Enable auto switch to Bluetooth | Play files in TF card now, if there is audio or call on Bluetooth, then auto switch to Bluetooth |
| AT+CK00 | Disable auto switch to Bluetooth | |
| AT+CG01 | Enable Bluetooth background | Release Bluetooth when playing files in TF card |
| AT+CG00 | Disable Bluetooth background | |
| AT+B201 | Enable Bluetooth call function | |
| AT+B200 | Disable Bluetooth call function | Cannot call through Bluetooth |
| AT+B301 | Enable Bluetooth audio function | |
| AT+B300 | Disable Bluetooth audio function | Connected, cannot play music |
| AT+B401 | Enable BLE function | |
| AT+B400 | Disable BLE function | BLE name cannot be searched, the chip does not broadcast out |
| AT+B501 | Enable EDR function | |
| AT+B500 | Disable EDR function | The audio Bluetooth name cannot be searched, the Bluetooth audio play function disabled |
| AT+BS123456781234 | Set Bluetooth MAC address | EDR MAC address: 0x12 0x34 0x56 0x78 0x12 0x34 BLE MAC address: the first byte of the EDR MAC address + 1 BLE MAC address: 0x13 0x34 0x56 0x78 0x12 0x34 |
Query
| Command | Function | Description |
|---|---|---|
| AT+QT | Query baud rate | Return “QT+05”, means the baud rate is 115200 01-06(9600, 19200, 38400, 57600, 115200, 25600) |
| AT+QN | Query hint tone | Return “QN+01”, means hint tone enabled 00-disable; 01-enable |
| AT+QK | Query auto switch to Bluetooth | Return“ QK+01”, means auto switch to Bluetooth function enabled 00-Disable; 01-Enable |
| AT+TE | Query password | |
| AT+TD | Query Bluetooth name | |
| AT+TA | Query Bluetooth MAC address | |
| AT+TM | Query BLE name | |
| AT+TB | Query BLE MAC address | |
| AT+T1 | Query whether pair password enabled | Return “T1+01”, enabled 00-disable；01-enable |
| AT+T2 | Query whether Bluetooth call function is enabled | Return “T2+01”, enabled 00-disable；01-enable |
| AT+T3 | Query whether Bluetooth audio function is enabled | Return “T3+01”, enabled 00-disable; 01-enable |
| AT+T4 | Query whether BLE function is enabled | Return “T4+01”, enabled 00-Disable; 01-Enable |
| AT+T5 | Query whether EDR function is enabled | Return“T5+01”, enabled 00-disable；01-enable |
API Description
/**
* @brief Set volume
* @param volume(0-30)
* @return true or false
*/
bool setVOl(uint8_t vol);
/**
* @brief Set working mode
* @param eFunction_t
* @return true or false
*/
bool switchFunction(eFunction_t function);
/**
* @brief Set play mode
* @param ePlayMode_t
* @return true or false
*/
bool setPlayMode(ePlayMode_t mode);
/**
* @brief Play control Only valid for playback by TF card and U-disk
* @param ePlayControl_t
* @return true or false
*/
bool playControl(ePlayControl_t cmd);
/**
* @brief Next
* @return true or false
*/
bool next();
/**
* @brief Last
* @return true or false
*/
bool last();
/**
* @brief Play the N-th file, play song of the specified number
* @param specified number
* @return true or false
*/
bool playSpecFile(uint16_t number);
/**
* @brief Play song of the specified path
* @param specified path
* @return true or false
*/
bool playSpecFile(const char* path);
/**
* @brief Delete the currently playing file
* @return true or false
*/
bool delCurFile();
/**
* @brief Dial a phone number
* @param phone number
* @return true or false
*/
bool callOut(const char* phoneNumber);
/**
* @brief Call control
* @param eControltalk_t
* @return true or false
*/
bool controltalk(eControltalk_t cmd);
/**
* @brief Obtain bluetooth status
* @return eBtStatus
*/
eBtStatus getBtStatus();
/**
* @brief Obtain calling phone number
* @return phone number
*/
String getTelNumber();
Other Supplementary Information
To use BLE Pass-through, please connect to BT401-BLE
To use SPP Pass-through, please connect to BT401-AUDIO
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