Crate embedded_multi_page_hmi 

Embedded Multi-Page HMI

The embedded multi-page HMI combines a resource constraint display output and a constraint fixed button input by an interaction model.

Input

Input is limited to a small set of buttons.

Depending on the amount of buttons several interaction models are predominant. The buttons get a semantic meaning, and allow for certain interaction models. The more buttons there are the more convenient the interaction model is.

Button	Semantics	Assigned activity
first	action	activate, confirm, trigger, modify, …
second	next	select the next item
third	previous	select the previous item in list
fourth	back	navigate to the previous position
fifth	home	go to home page, reset

A rotary knop can be modelled as three buttons (action, next, previous).

Output

Display

The output is on one single display. The display can be

• alphanumerical,
• or graphical display.

Pages

The output is organized in pages. Exactly one page is displayed at a time on the display.

Every page has a lifetime.

Page	Meaning
Home	Is Mandatory; Is the fallback Page, Start point for all navigation
Startup	Optional; Shown during init; no interaction; replaced by Home
Shutdown	Optional; Shown during de-init; no interaction

Pages have the following properties:

• Can handle input interactions.
  • this can be used to capture input e.g. of numbers, flags that get delegated to a data model underneath
• Have a lifetime: How long are they displayed w/o input
  • If the lifetime is over, automatically the home page or next page is activated.
• Pages can have dynamic content (like current time, temperature, etc) that is updated on a regular base

Interaction Models

Between pages can be navigated, triggered by an interaction or automatically triggered by events (from timer or value change)

One Button - Sequence of Pages

• The action interaction activates the next page.
• Inside the pages no activity is possible

Two Button/ Three Button - Sequence of Pages

More than one button input allows inter-page interaction.

Three button interaction is like two button interaction, except that previous is a shortcut for iterating with next through a looped list of items.

There are information pages and setting pages.

Information pages:

• purely display (dynamic) information
• do not allow for internal interaction

Setting pages:

• Allow to select items or enter values

• The next interaction activates the next info page.

• The action interaction activates the setting page(s).

• Inside the info pages no activity is possible

• Inside the setting page(s) it is possible to

  • select items with next interaction
  • activate items with action interaction
  • Go back to home (info) page could be item to select and activate

Modules

page

Home of several general purpose page implementations

Structs

CellSetting

A setting implemented using Cell

PageError

Any error a page update my run into

PageLifetime

PageLifetime enables a page to automatically switch to another page after a certain time.

PageManager

The PageManager is responsible for switching among pages while pages do not know about other pages. The PageManager also dispatches events and updates the current page.

Enums

Interaction

Possible Interactions derived from the input

PageNavigation

Page navigation events dispatched by pagemanager

Traits

PageBaseInterface

Data structures that implement the Page trait are Pages and can be handled by the PageManager type

PageInteractionInterface

A page is responsible to implement user interaction

PageInterface

Data structures that implement the Page trait are Pages and can be handled by the PageManager type

Setting

A setting can be set and get