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GalaxyBudsRFCommProtocol.md

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Galaxy Buds RFComm Protocol Notes

[TOC]

Packets

General notes

FrameType: if payload size > 250 then 1 else 0

ExtendedFrameType: if payload size > 250 then 2 else 1 (byte)

Non-fragmented

Name Value (hex) Size
Preamble FE 1 byte
Type (Req = 0 or Rsp = 1)[1] 0x 1 byte
Payload size xx 1 byte
Message ID xx 1 byte
Message payload ... dynamic[2]
Checksum[3] (CRC16-CCITT)[4] xx xx 2 byte
Postamble EE 1 byte

[1] maybe more types -> used by isFragment()

[2] calculation: x = payload size - 1 byte (msg_id) - 2 bytes (crc)

[3] checksum of the Message ID and content

[4] more details: https://gist.github.com/ThePBone/435b625418945592d7a0a3f04adc67b0

Fragmented

Skipped for now; only used for large data transmissions (e.g. Firmware OTA, Core Dumps)

Messages

Send

MSG_ID_UPDATE_TIME

Index Name Description Size
0 Timestamp Milliseconds since 1970 as long byte buffer 8 byte
8 Timezone Timezone offset (amount of ms to add) as int byte buffer 4 byte

MSG_ID_MANAGER_INFO

Index Name Description Size
0 Hardcoded Always contains 1 1 byte
1 IsSamsungDevice Samsung device = 1, Other = 2 1 byte
2 AndroidSdk Android Version as SDK Integer 1 byte

Might be used to enable phone-exclusive functions

MSG_ID_VOICE_NOTI_STATUS

Index Name Description Size
0 Status 0 or 1 1 byte

Used to prepare for client-based TTS voice notifications. Does not seem to have any effect

MSG_ID_NOTIFICATION_INFO

Index Name Description Size
0 ? 0 or 1; Probably used to play an internal beep sound 1 byte

Used for notifications. Does not seem to have any effect

MSG_ID_GAME_MODE

Index Name Description Size
0 Mode? Set to 2 if phone supports Game Mode, otherwise unknown 1 byte

Unknown effect. Only used on Samsung devices with Game Mode available.

MSG_ID_EQUALIZER

Index Name Description Size
0 Enabled 0 or 1; Enable EQ 1 byte
1 Preset 0-10; Preset 1 byte
Presets
Preset ID Description
0 Bass boost (optimized for Dolby)
1 Soft (optimized for Dolby)
2 Dynamic (optimized for Dolby)
3 Clear (optimized for Dolby)
4 Treble boost (optimized for Dolby)
5 Bass boost
6 Soft
7 Dynamic
8 Clear
9 Treble boost

MSG_ID_LOCK_TOUCHPAD

Index Name Description Size
0 Enabled 0 or 1; Touchpad lock 1 byte

MSG_ID_SET_AMBIENT_MODE

Index Name Description Size
0 Enabled 0 or 1; Enable ambient sound 1 byte

MSG_ID_AMBIENT_VOICE_FOCUS

Index Name Description Size
0 Type 0 or 1; Default or VoiceFocus 1 byte

MSG_ID_AMBIENT_VOLUME

Index Name Description Size
0 Volume 1-5; Ambient volume 1 byte

MSG_ID_MUTE_EARBUD

Index Name Description Size
0 LeftMuteStatus 0 or 1; Mute 1 byte
1 RightMuteStatus 0 or 1; Mute 1 byte

Only available in FindMyGear mode

MSG_ID_SET_TOUCHPAD_OPTION

Index Name Description Size
0 LeftOption ID of Action to be set on the left device 1 byte
1 RightOption ID of Action to be set on the left device 1 byte
Available Actions
ID Description
0 Voice assistant
1 Quick ambient sound
2 Volume (if set on left: volume down, else volume up)
3 Ambient sound
4 Spotify SpotOn (requires client compatibility)
5 Other... (left only)
6 Other... (right only)

MSG_ID_MAIN_CHANGE

Index Name Description Size
0 Device Hand-over main connection (1 = left, 0 = right) 1 byte

Parameter-less messages

Message ID Description
MSG_ID_FIND_MY_EARBUDS_START Starts playing loud beeping sounds
MSG_ID_FIND_MY_EARBUDS_STOP Stops playing and return to the default BT audio
MSG_ID_DEBUG_SERIAL_NUMBER Returns serial number for both devices
MSG_ID_RESET Resets device to factory defaults and responds with a result code
MSG_ID_DEBUG_GET_ALL_DATA Returns version data and sensor measurements
MSG_ID_DEBUG_BUILD_INFO Returns device string for both devices
MSG_ID_LOG_SESSION_OPEN Open logging session and disconnect the music stream
MSG_ID_LOG_SESSION_CLOSE Close logging session and resume the music stream
MSG_ID_BATTERY_TYPE Returns battery type strings for both devices

Receive

MSG_ID_EXTENDED_STATUS_UPDATED

Index Name Description Size
0 VersionOfMR 1 or 2; Also used to check for the new ambient module 1 byte
1 EarType 0 or 1; Unused[1] 1 byte
2 DeviceBatGageL 0-100%; Battery (L) 1 byte
3 DeviceBatGageR 0-100%; Battery (R) 1 byte
4 TwsStatus 0 or 1; Coupled device status[1] 1 byte
5 MainConnection 0 (R) or 1 (L); Current main connection[1] 1 byte
6 WearingStatus 0 (none), 1 (L), 16 (R), 17 (both)[1] 1 byte
7 AmbientSoundEnable 0 or 1; Is ambient sound enabled[1] 1 byte
8 AmbientSoundType 0 or 1; Is voice focus mode enabled[1] 1 byte
9 AmbientSoundVolume Ambient sound volume[2] 1 byte
10 EqualizerEnable 0 or 1; Is EQ enabled[1] 1 byte
11 EqualizerType 0-10[3]; EQ type 1 byte
12 <dynamic> Touch lock state (+ one option slot, if byte 13 not used) 1 byte
13 <dynamic> (optional) Touch option (L and R)[4] 1 byte

[1] additional code: -1 (test code)

[2] post-calculation: int saved = vol + -1; -> expected range [1;5]

[3] range: [0;10] -> if (type >= 5) type -= 5; -> actual range: [0;5]

[4]byte 13 is only required for touch actions that can set two different actions for L and R long press at the same time. If only one option slot is sufficent, byte 13 is not transmitted and the single action is stored in byte 12 alongside the touch lock state which can be either 0 or 1.

The device probably expects a response. The same SPPMessage should be sent back (response type) and after that, you should transmit basic (android) manager app information. (Refer to MSG_ID_MANAGER_INFO)

Byte 12 and 13

Single touch option

  • Byte 13 is not transmitted, instead the option is stored inside byte 12
  • Used by 'volume button preset'
byte lock_touchpad_status = (sppMessage.getParameters()[12] & 240) >> 4;
byte touchpad_option = sppMessage.getParameters()[12] & 15;
storeLeftTouchpadOption(touchpad_option);

Double touch option

  • Byte 13 is transmitted, both options are stored inside
  • The touch lock state remains in byte 12
byte lock_touchpad_status = sppMessage.getParameters()[12] & 255;
byte touchpad_option_l = (sppMessage.getParameters()[13] & 240) >> 4;
byte touchpad_option_r = sppMessage.getParameters()[13] & 15;

MSG_ID_STATUS_UPDATED

Index Name Description Size
0 EarType 0 or 1; Unused[1] 1 byte
1 DeviceBatGageL 0-100%; Battery (L) 1 byte
2 DeviceBatGageR 0-100%; Battery (R) 1 byte
3 TwsStatus 0 or 1; Coupled device status[1] 1 byte
4 MainConnection 0 (R) or 1 (L); Current main connection[1] 1 byte
5 WearingStatus 0 (none), 1 (L), 16 (R), 17 (both)[1] 1 byte

[1] additional code: -1 (test code)

The device probably expects a response. The same SPPMessage should be sent back (response type) and after that, you should transmit basic (android) manager app information. (Refer to MSG_ID_MANAGER_INFO)

MSG_ID_RESP

Index Name Description Size
0 Action Original ID of message sent to the earbuds 1 byte
1 ResultCode Result/error code (0 = Success) 1 byte
2 ExtraData (opt.) Only used if the MainConnection has been manually changed 2 byte

Generic response. Android app always sends a time update if received.

Exceptions

[UNCHECKED] If byte 0 corresponds to 112, then we're looking at the response message of a manual MainConnection change. In this case, byte 2 describes which earpiece is declared as the main connection 0 (R) or 1 (L).

Other notes

  • (Extended) Status Update requires (?) RESP with result code