MQTT API Reference¶

The RTK Base uses MQTT for real-time communication, configuration, and data streaming.

Connection Details¶

• Broker: mqtt.yamabikorobots.net (production)
• Port: 8883 (MQTT over TLS)
• Client ID: <serial_number>
• Authentication: TLS client certificates

Topic Structure¶

All topics use the format: base/<SN>/<action>

Where <SN> is the RTK Base serial number (e.g., BRRB000021)

DRTK Publication¶

base/{SN}/drtk¶

Type: Publish

Raw RTCM data stream. Published as soon as RTCM data is available from the ZED module.

Behavior:

• Payload is raw bytes (binary RTCM data)
• Published continuously when operational
• If transfer/mqtt/rtcm/optimization is enabled, requires keep-alive messages

Keep-Alive Mechanism: When optimization is enabled, robots must publish to base/keepAlive/<NAME>/<SN> periodically to maintain the RTCM stream.

REST-like API over MQTT¶

The RTK Base emulates its REST API over MQTT for environments where HTTP is not available.

Info Request¶

Request: - Topic: base/{SN}/info/get - Payload: unused (empty)

Response:

• Topic: base/{SN}/info
• Payload: JSON info object (same as HTTP /get-info)

Change Configuration¶

Request: - Topic: base/{SN}/change/post - Payload: JSON configuration object

Response:

• Topic: base/{SN}/change/resp
• Payload: Response JSON with result and leftover fields

See REST API for available configuration fields.

System Commands¶

Request: - Topic: base/{SN}/system/post - Payload: Parameter string (the part after ? in HTTP URI)

Response:

• Topic: base/{SN}/notice
• Payload: Text output from command

Generic Command¶

Request: - Topic: base/{SN}/cmd - Payload: JSON or system command string

See command formats below.

Debug Logs¶

Log Retrieval¶

Request: - Topic: debug/log/get - Payload: unused

Response:

• Topic: debug/log/lines/{IDX}
• Payload: One log line per message
• QoS: 1 (at least once delivery)
• Index: {IDX} is the line index

Value Storage (NVS)¶

Get Value¶

Request: - Topic: base/{SN}/val/get - Payload: ID (value identifier)

Response:

• Topic: base/{SN}/val
• Payload: ID HEXVALUE

Set Value¶

Request:

• Topic: base/{SN}/val/set
• Payload: ID HEXVALUE

Response:

• Topic: base/{SN}/val/ack
• Payload: Acknowledgment

Delete Value¶

Request:

• Topic: base/{SN}/val/del
• Payload: ID

Response:

• Topic: base/{SN}/val/ack
• Payload: Acknowledgment

UBX Protocol¶

UBX Forwarding¶

Request: - Topic: base/{SN}/ubx/post - Payload: Binary UBX packet or hex string

Behavior: - Upon receiving this command, the RTK Base forwards all UBX packets to MQTT for 30 seconds - Forwarding format follows the format of the last received packet (binary or hex)

Response:

• Topic: base/{SN}/ubx
• Payload: UBX packets

Spectrum Analyzer¶

Get Spectrum Data¶

Request: - Topic: base/{SN}/span/get - Payload: unused

Response:

• Topic: base/{SN}/span
• Payload: JSON spectrum data

Example Response:

{
  "bands": [
    {
      "center": 1583461250,
      "span": 128000000,
      "res": 500000,
      "pga": 57,
      "buck": [67, 68, 67, 66, ...]
    },
    {
      "center": 1224006250,
      "span": 128000000,
      "res": 500000,
      "pga": 57,
      "buck": [67, 69, 69, 70, ...]
    }
  ]
}

Satellite Information¶

Get Satellite Data¶

Request: - Topic: base/{SN}/sat/get - Payload: unused

Response: - Topic: base/{SN}/sat - Payload: JSON array of satellite objects

Example Response:

[
  {
    "gnss": "gps",
    "svid": 5,
    "pr": 2,
    "q": 7,
    "cno": 43,
    "elev": 48,
    "azim": 212,
    "flags": ["used", "healthy", "diffcorr"],
    "orbit": "ano",
    "corr": ["sbas", "pr", "doppler"]
  },
  {
    "gnss": "gal",
    "svid": 24,
    "pr": 3,
    "q": 7,
    "cno": 38,
    "elev": 27,
    "azim": 46,
    "flags": ["used", "healthy"],
    "orbit": "ano",
    "corr": []
  }
]

Fields:

• gnss: GNSS system (gps, glonass, gal, bds, sbas, navic)
• svid: Space Vehicle ID
• pr: Pseudorange
• q: Quality indicator
• cno: Carrier-to-Noise ratio (dB-Hz)
• elev: Elevation angle (degrees)
• azim: Azimuth angle (degrees)
• flags: Status flags (used, healthy, diffcorr)
• orbit: Orbit source (ano, eph, alm)
• corr: Applied corrections

Fast SVIN Query¶

Request RTCM Source¶

See Fast SVIN technical documentation.

Query:

• Topic: base/{SN}/query/rtcm/req
• Payload: lat=LAT,lon=LON

Response:

• Topic: base/{SN}/query/rtcm/resp
• Payload: topic=RTCM_TOPIC,keepalive=KA_TOPIC,dist=DISTANCE,prio=PRIO

Production Mode¶

Note: These interfaces are only available when the RTK Base is in production test mode.

UI Display¶

Topics:

• production/base/{SN}/UI/USER-TITLE: Display title (string)
• production/base/{SN}/UI/USER-TEXT: Display text (string)
• production/base/{SN}/UI/INTERACT: Interaction command

Interaction Types:

• Button: OK,CANCEL,PASS
• Text Input: TEXT;name (name = default text)
• List: LIST;a;b;c;d;e

Test Report¶

Topic: production/base/{SN}/UI/test-report

Payload: JSON test results

UI Interaction Response¶

Topic: production/base/{SN}/UI/INTERACT/resp

Payload: User response (button name, list item, or text input)

Device Command¶

Topic: production/base/{HW_ID}/cmd

Commands:

• whereAreYou: Start 10-second Christmas blinking animation (for locating device)
• Any other payload: Treated as standard command

Device Ready¶

Topic: production/base/{SN}/ready

Payload: 1 (published when base is ready for production test)

Who Is Alive¶

Topic: production/whoIsAlive

Response: production/base/{SN}/ready with payload 1

Keep-Alive¶

base/keepAlive/{NAME}/{SN}¶

Type: Subscribe (base listens)

Used to trigger RTCM publication when optimization is enabled.

Parameters:

• {NAME}: Identifier of the robot or entity requesting data
• {SN}: RTK Base serial number

Behavior:

• Robots must publish periodically to this topic
• RTCM stream stops if no keep-alive received for 5 minutes
• Prevents unnecessary bandwidth usage

JSON Command Format¶

Firmware Update¶

{
  "cmd_type": "updateBase",
  "cmd_param": {
    "url": "http://myStaticFileServer.com/RTK_BASE_4.0.2.bin"
  }
}

ZED Configuration Update¶

{
  "cmd_type": "updateZedConfig",
  "cmd_param": {
    "url": "http://myStaticFileServer.com/Zed_Config_file_1.3.txt"
  }
}

QoS Levels¶

Security¶

• All production MQTT traffic uses TLS encryption
• Client certificates are used for authentication
• Certificate lifecycle managed automatically
• Production test mode uses separate topic namespace