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System Overview — MQTT & Device Views

The CC2 device is controlled by MQTT commands (downlink) and reports state via MQTT data (uplink). What the wearer sees on the screen is defined by Device Views (DVs) — JSON files stored in /dvs/.

These three layers are connected by shared key paths and widget names.

How a command changes the screen

duress_app/ Backend
      │
      ▼  MQTT downlink
┌──────────────────────────────────────────┐
│  {"app":{"duress":{"data":{"alerts":[    │
│    {"id":"1","subj":"Nurse A",          │
│     "location":"ICU","resp":0}          │
│  ]}}}}                                   │
└──────────────────────────────────────────┘
      │
      ▼  Device receives MQTT
┌──────────────────────────────────────────┐
│  duress DV  →  alerts msglist           │
│  Widgets updated: subj, location, resp  │
│  DED skeleton shows alert detail        │
└──────────────────────────────────────────┘

Key paths that link MQTT to DVs:

MQTT key	DV widget bound to it	Used in
`app.duress.data.alerts`	`alerts` msglist	duress
`devcfg.ui.lang`	`devcfg.ui.lang` (editable)	syscfg
`devcfg.ui.enable_lock`	`devcfg.ui.enable_lock` (bool)	syscfg
`devcfg.alert.showFlash`	`devcfg.alert.showFlash` (bool)	duress (page 2)
`devdata.power.gauge`	`devdata.power.gauge` (dynamic)	sysinfo, allocated_home
`devdata.fw.device_id`	`devdata.fw.device_id` (dynamic)	sysinfo, allocated_home, duresstest

How a user action sends data back

Wearer taps "Acknowledge" button on alert
      │
      ▼  DV action fires
┌──────────────────────────────────────────┐
│  {"a":"updateRemote","p":"yes"}         │
└──────────────────────────────────────────┘
      │
      ▼  Device sends MQTT uplink
┌──────────────────────────────────────────┐
│  {"app":{"duress":{"alerts":{           │
│    "id":"1","ackyes":"yes"              │
│  }}}}                                    │
└──────────────────────────────────────────┘
      │
      ▼  duress_app/ Backend receives it

The two data sources for user identity

Source	Widget	Used for
Device config (allocdata)	`user_name`, `user_role`	Wearer sees their own name on `duresshome`, `badge_lock`
Portal (MQTT `app.duress`)	`subj`, `location`	Recipient sees the alert sender’s name on `duress`

They are completely independent. Changing the device’s user_name does not change the notification name the duress_appsends. The portal uses its own associatedUser field.

MQTT downlink commands — what the backend can send
MQTT uplink data — what the device reports
Device Views — what the wearer sees
duress_appdocs — how the duress_appmanages assignments