Lab: Telemetry Pipeline and MQTT on Twin

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BS-10: MQTT Publisher & Subscriber Asst. Prof. Dr. Santi Nuratch (KMUTT)

Videos by Asst. Prof. Dr. Santi Nuratch, Department of Control Systems and Instrumentation Engineering, Faculty of Engineering, King Mongkut's University of Technology Thonburi (KMUTT) · The whole series in the playlist AIoT Foundation

Course 2 · Module 5 Type: Hands-on (classify · Live Data quality · MQTT pub/sub · fault injection) Suggested time: ~3.5–4 hours

Read first: Lesson · Lab notes · ← Table of Contents · ← M04 · M06 →

Useful references during the lab

Document	Use when
M04 lab · the ex05 walkthrough	The basic Live Data consumer
Course 1 M06	MQTT on the firmware / QoS
Hackathon `web-app/`	ex08, ex09–ex15
Bitstream Studio	Start broker · Twin publish

Lab Goals

Separate and send at least one instance each of the Telemetry / State / Event concepts
Check on a dashboard or a subscriber that the fields/units are correct
Start an MQTT broker in Studio and complete at least one pub/sub pair
Try at least one lossy / disconnect / schema-break case
Fill in telemetry-mqtt-lab-notes.md

Prerequisites

M04’s bring-up passed (a stable Link · know Simulator XOR Bitstream)
The Hackathon folder has web-app/
Know how to Serve Web App Folder over HTTP (M04)
A lab-notes/ folder for evidence

Lab A — Classify & design topics (required)

Design (on paper, or in the lab notes):

Telemetry — a topic + one example JSON block + an approximate rate
State — a topic + when it will be sent (a mode change / LED / Link)
Event — a topic or event name + a short condition

You may use the example structure from the lesson, such as:

device/<id>/devkit-twin/telemetry
device/<id>/state
device/<id>/event/<name>

Pass when: a teammate reads the topic and correctly guesses the data type, without having to guess from the payload alone

Lab B — Live Data quality with `ex08` (required)

Link Studio (a single mode)
Serve web-app/ → open ex08_stale_and_route.html
Note the route, COM open, last origin
Make at least one sensor go stale, then return to fresh
Take a screenshot of the event log + pills

Pass when: you can explain that stale is a host-side Event when telemetry has a gap — and the origin matches Studio’s mode

Lab C — MQTT broker + `ex09` subscriber (required)

In Bitstream Studio: Start broker
Open ex09_mqtt_subscriber.html — wait for connected
Publish to the topic the web page subscribes to (default device/devkit-twin-01/devkit-twin/telemetry, or per ?device= / ?topic=)
- Publish source: the DevKit Twin MQTT tab / Sensor Studio connectivity / another tool you have
Confirm Last payload’s fields and units match
Take a paired screenshot: the publish source + the ex09 page

Pass when: the message count is ≥ 1, and the JSON can be explained as Telemetry (or the intended type)

Lab D — Pipeline / schema drill (recommended)

Choose at least one:

Remove a field from the payload and see exactly where the subscriber/dashboard breaks
Deliberately send the wrong unit, and note that the UI “still looks fine but means the wrong thing”
Open ex14 and try QoS + retain on lab/qos-demo, then have a friend open a subscriber (such as ex11) after you’ve retained a message

Pass when: there is at least one line of “what broke / what didn’t” in the lab notes

Lab E — Lossy / reconnect (recommended — part of the complete deliverable)

Choose at least one case, and fill in the table in the lab notes:

Case	Example way to do it
Stop / Start the broker briefly	Watch ex09 go `reconnecting` → `connected`
Briefly stop the publisher	Watch for a gap · or ex08’s stale
Close the ex09 tab and reopen it	If a state topic has retain — do you get the latest value or not?

Pass when: you can name the behaviour seen (drop / retry / reconnect / stale) without guessing

Lab F — Optional ladder

If time remains, choose more:

ex10 publishing from the browser
ex12 gauges
ex15 a combined dashboard
Publishing from real firmware after Wi‑Fi (C1 M06) into the lab’s broker

Deliverables checklist

Labs A–C passed
Lab E (or at least Lab D, if time is short)
telemetry-mqtt-lab-notes.md filled in completely
Screenshot evidence: ex08 + ex09 (+ schema/lossy, per what you did)

Troubleshooting

Symptom	Approach
ex08 is disconnected	Studio/the bridge · serve the correct `web-app/` folder
ex09 is stuck connecting	Start broker · check `ws://127.0.0.1:8883/mqtt`
connected, but Waiting for messages	No publisher exists yet · the topic doesn’t match · check `?device=` / `?topic=`
Live Data is fine, MQTT is empty	Different pipes — don’t fix the firmware before checking the broker/topic
The origin is confusing	Don’t mix Simulator + Bitstream · clear it and Link fresh
Retain makes a value “stuck”	Check you’re experimenting on the lab topic, not a dense telemetry one

Lesson · Lab notes · Table of Contents · M06 →

Cite this lesson

If you teach from this lesson or reuse it in slides or documents, credit it with the text below. If you changed it, add (adapted) after the title.

"Lab: Telemetry Pipeline and MQTT on Twin" from TESA Open Knowledge by the Thai Embedded Systems Association (TESA), https://github.com/tesaiot/tesa-qualification-program, licensed under CC BY-NC 4.0

Thai attribution: "แล็บ: ท่อ telemetry และ MQTT บน Twin" จาก TESA Open Knowledge โดยสมาคมสมองกลฝังตัวไทย (Thai Embedded Systems Association: TESA) https://github.com/tesaiot/tesa-qualification-program สัญญาอนุญาต CC BY-NC 4.0

Lesson link: https://tesaiot.github.io/tesa-qualification-program/en/courses/digital-twin/m05-telemetry-cloud/l02-lab/

This lesson adapts the source below; keep its credit too.
https://github.com/drsanti/TESAIoT-Courses/blob/287c21814ba8c75f693136616dcd270349a15966/C2/M05/lab.md · Original content by Asst. Prof. Dr. Santi Nuratch (ผศ.ดร.สันติ นุราช), KMUTT. Course 2 (C2/) of drsanti/TESAIoT-Courses. TESA funded the work and holds the rights; published here under CC BY-NC 4.0. The upstream repository carries no licence file. Text kept faithful; structure, front matter, quizzes and notes added by TESA Open Knowledge.

Full guide: how to cite TESA

Content is licensed CC BY-NC 4.0. Reuse it non-commercially and credit the Thai Embedded Systems Association (TESA) every time. · How to cite TESA