mermaids

mqtt_display/docs/critical_data_flow_points.mermaid

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+graph TD
+    START[MPU reads @50ms = 20 Hz] --> A{IMU_CHANNEL<br/>try_send}
+    
+    A -->|Full| DROP1[❌ DROP: Channel full<br/>16 slots @ 50ms = 800ms buffer]
+    A -->|OK| B[Main Loop receive]
+    
+    B --> C[Drain loop:<br/>Get freshest reading]
+    C --> D{Time check:<br/>≥3s since last?}
+    
+    D -->|No| E[Skip MQTT]
+    D -->|Yes| F{mqtt_set_imu<br/>try_lock IMU_LATEST}
+    
+    F -->|Locked| DROP2[❌ SKIP: Mutex busy]
+    F -->|OK| G[Store payload]
+    
+    E --> H[show_imu]
+    G --> H
+    
+    H --> I{DISPLAY_CHANNEL<br/>try_send}
+    I -->|Full| DROP3[❌ DROP: Display slow<br/>8 slots @ 100ms = 800ms buffer]
+    I -->|OK| J[Display renders]
+    
+    G --> K[MQTT Task loop]
+    K --> L{IMU_LATEST<br/>try_lock}
+    
+    L -->|Empty/Locked| M[Skip this iteration]
+    L -->|Has data| N[Send to broker<br/>QoS0 no retain]
+    
+    N --> O{TCP send result}
+    O -->|Fail| RECONNECT[❌ Session dies<br/>Reconnect in 5s]
+    O -->|OK| P[✅ Data sent]
+    
+    style DROP1 fill:#ffcccc
+    style DROP2 fill:#ffcccc
+    style DROP3 fill:#ffcccc
+    style RECONNECT fill:#ffcccc
+    style P fill:#ccffcc