Cheatsheet — MQTT / MQTTs (M06)

Course 1 · Module 6

Lesson · Lab · ← Table of Contents

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Concepts

Term	One-liner
Broker	ตัวกลาง pub/sub
Topic	ช่องชื่อแบบลำดับชั้น
QoS	ระดับรับประกันการส่ง (0/1/2 ในสเปก)
Retain	เก็บข้อความล่าสุดของ topic
MQTTs	MQTT + TLS (พอร์ตมัก 8883)

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Ownership

Core	Role
CM55	cm55_trigger_mqtt_*, JSON encode
CM33	Wi‑Fi + cy_mqtt_* session

Wi‑Fi CONNECTED before MQTT.

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CM55 commands

cm55_trigger_connect(ssid, pass, 0);
cm55_get_wifi_status(&st);

cm55_trigger_mqtt_policy_set(flags);
cm55_trigger_mqtt_connect();
cm55_get_mqtt_status(&mqtt);   /* state 2 = CONNECTED */
cm55_trigger_mqtt_disconnect();

Policy ideas: AUTO_CONNECT | TELEMETRY_PUBLISH | MQTT_ENABLED (factory often 0x07)

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Config placeholders

cfg.broker_host = "YOUR_BROKER_HOST";
cfg.port = 1883;   /* or 8883 */
cfg.tls  = 0;      /* 1 for MQTTs */
cfg.username / cfg.password = "YOUR_*";
cfg.root_ca_len = 0; /* may use embedded CA when tls=1 */

Topics: bitstream/<MAC12>/sensors|actuators|status
Helper: cm33_mqtt_format_mac_topic(...)

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Payload

bs_mqtt_telem_encode_json_readable(...);
/* primary path = JSON string; no CBOR path in current MQTT stack */

Telemetry publish behavior in current SDK: QoS0, retain false (teach spec vs implementation)

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Security checklist

• Prefer TLS for anything beyond a lab LAN
• Do not commit Wi‑Fi / broker passwords
• Know whether broker needs user/pass
• Mutual TLS client cert: not in standard config v3

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Host tools

Tool	Link
Examples	dev.tesaiot.dev
Hackathon MQTT	TESAIoT_Hackathon ex09–ex15
Studio	Bitstream Studio
Concepts	MQTT Essentials

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Lab log

Item	Your value
Wi‑Fi SSID
Broker host:port
tls (0/1)
Client id / MAC topic
Publish evidence
Subscribe evidence

Lesson · Lab · ← Table of Contents