| [Top] | [Contents] | [Index] | [ ? ] |
This document describes version 1.0 of MEX, the Menu EXecutor. MEX is a generic interpreter for the binary menu format which is generated by MLC, the Menu Language Compiler. The current version of MEX is written in Ansi-C and compiles with icc11 (68HC11) or djgcc (Intel x86). Related information about ML (Menu Language), can be obtained in the following document: See section `Introduction' in A Menu-Language Introduction.
Copyright (C) 1997-2001 Hubert Hoegl Edition 0.9.1
Last change: April 7 2001
1. Document History 2. Introduction 3. Menu Navigation 4. Line Navigation and Field Editing 5. Keyboard Layouts 6. Programming Interface 7. Implementation Notes
Added this section. No entries so far.
A typical user interface for embedded systems consists of a tiny keyboard and a LC-display. The M-Language was designed to comfortably describe menu-based user interaction with embedded system euqipped with these two I/O components. The menu description can be compiled into a binary menu format and linked with an embedded application. Control of the LCD and the keyboard is done by a function (or process in a multitasking environment) which interprets the binary menu data, called "Menu Executor" in the further context.
Typical LC-display sizes are 16x2, 16x4, 20x2 and 20x4. All these formats can be controlled with MEX. The following figure shows a 16x4 display.
column column 1 16 v v +----------------+ |................| <- row 1 |................| |................| |................| <- row 4 +----------------+ |
The minimum requirement for the keyboard consists of 5 keys. These are the four cursor keys (left, right, up, down) and a tabulator key.
3.1 The LCD Layout 3.2 Moving in the hierarchy
MEX uses a fixed LCD layout. The top line of the display is called the status line and shows miscellaneous information about the current status of the user interface. Thus on a four line display there are three remaining lines which can be used for displaying menu data. On a two line display there will be only one menu-line below the status line.
A future version of MEX may also be able to display a footer line on a four line display. In this case two menu lines will be displayed.
+----------------+
|TTTTTTTTTTTTNLLK| <- Status line
|C..............S| <- Menu line 1
|C..............S| <- Menu line 2
|C..............S| <- Menu line 3
+----------------+
|
The display layout is divided into fields, which are denoted by characters in the above figure. The table below explains the fields:
By using the four cursor keys one can move freely within the hierarchical menu structure. The following figure shows how these four cursor keys should be mounted:
KEY_UP
KEY_LEFT KEY_RIGHT
KEY_DOWN
|
The keys KEY_UP and KEY_DOWN move the previous or next line in a menu-table. KEY_RIGHT steps into a submenu and KEY_LEFT jumps out of a submenu.
Accessing protected submenus: When a submenu is protected by a password
(this is indicated by the rightmost line-character equal to P) then
prior to entering the submenu a password has to be typed in the keyboard.
The password is specified as the attribute `key' in the menu description
file. The password consists of a string of integers, for example
(key '401302') |
A typical situtation is shown in the figure below:
+----------------+
|Pwd:...... |
| Sensors... >|
| Parameter... >|
|>System... P|
+----------------+
|
On entering menu-line 3 ("System...") the status line changes to a password entry field. After the string "Pwd:" there are as many points as there are digits in the password (in our case six). On every subsequent keypress a `.' changes to a `*' character indicating how many password character already have been entered.
For entering the required numeric passord value, each key has also a fixed numerical value. Thus on a minimal five-key keyboard one can represent the numbers zero to four. Thus one may not choose numbers bigger than four in the key-attribute of the menu description file when using the minimal keyboard.
When all password characters have been chosen right, than immediately after pressing the last password character one enters the submenu. If the password was wrong, the attempt to enter the submenu is ignored. In either case the status line will again change to show the typical contents.
The principle of navigation within a line ("horizontal navigation") is very simple. It is done solely with the tabulator key. If a menu-line contains no writeable line components, then pressing the tabulator key has no effect. If there is a writeable field (or also called `entry field') somewhere within the line (indicated by the line-navigation character in the status line), then subsequently pressing the tab-key will position the "horizontal" line cursor (blinking black box) on this field.
Now assume the cursor is positioned on the first character of an entry field. The way to change its value is dependant on the type of the entry field. When using the minimum keyboard layout (five keys), all field entry is done via the four cursor keys. Note that while the horizontal cursor is displayed (blinking), one can not navigate through the menu hierarchy!
When the cursor is positioned on the final line-component in a line then the next keypress on tabulator will make the horizontal cursor disappear. Then again the cursor-keys have their menu-navigation functionality.
There are nine different types of entry fields(1).
The counter field is similar to the integer field, except that the displayed field value can only be increased or decreased by a fixed stepsize. The from-, to-, and step-values can be described in the menu specification.
The counter entry field is controlled via KEY_UP and KEY_DOWN. On pressing KEY_UP the field is increased by one step and pressing KEY_DOWN decreases the value by one step. No action results when the counter value would result past the maximum or below the minimum value.
The date entry field exists in a long and a short variant. They differ in the length of the year-field. The long one uses four digit year numbers and the short one only two digits.
|......12/04/1961| <- long date (day/month/year) |........12/04/61| <- short date |
The tab-key move the horizontal cursor from day to month to year on successive keypresses. Thus the whole field behaves as if it were composed of three subfields. Each single field can be adjusted according to the rules given for counter entry fields.
Sub-components.
The `date' entry field consist of three sub-components. In the example
above these are 12, 04 and 61 (in the short format).
In principle this is nothing more than three separate fields of type `dd' with string separators `:' and `.'. The only reason for introducing the compound types `date' and `time' was its better encapsulation. ML currently does not allow to specify how the different sub-components are handled, so MEX has to choose an appropriate field processing method. Currently all sub-components in `date' and `time' are of elementary type `counter'.
Currently there is no support for read-only or editable float components. If editable float fields should be used, then it is highly recommended to have a numerical keypad consisting of the keys zero to nine and a point.
The current version of MEX has only limited support for `integer' line components. As read-only fields one can use the type attributes `dd', `sdd', `sddd' and `DDD' (See section `Integer' in A Menu-Language Introduction.).
Currently there is no support for editable integer components. This is due to the fact that the basic keyboard layout consisting only of five keys. Integers can best be input with a numerical keypad containing the numbers zero to nine.
In an option entry field one selects an individual option by pressing the KEY_LEFT or KEY_RIGHT keys subsequently. On pressing the KEY_TAB key the option field is left and the callback handler is called.
Strings are currently only supported as read-only.
A switchbox is similar to an array of switches. Each of the switches can be in `off' or `on' position. When the horizontal cursor is initially positioned in a switchbox, the cursor is blinking on the leftmost switch. By pressing either KEY_LEFT or KEY_RIGHT, the blinking cursor can be moved within the switchbox. A switch can be turned on by pressing KEY_UP. KEY_DOWN turns the switch in the off state.
For explanation see the date entry field above. The time entry field is similar to the date entry field composed of three (long) or two (short) sub-components.
|........12:04.59| <- long time (hour:minute.second) |...........12:04| <- short time (hour:minute) |
The trigger entry field is shown as a single predefined character (currently the outline of a box). When the horizontal cursor is positioned on a trigger, then pressing any of the cursor keys results in jumping into the callback handler for this field.
Note the difference to the callback behaviour of the other entry types: With the other entry fields the callback function is always called when the entry field is finished by pressing the tabulator key. This behaviour is not satisfactory for the trigger field because stepping over a trigger field by pressing tab should not activate the callback.
Keys that must be available:
Suggested floorplan for the minimal keyboad
----------------------------------
UP
LEFT RIGHT TAB
DN
----------------------------------
|
Keys that optionally can be available:
Suggested floorplan for the extended keyboad
----------------------------------------------------
7 8 9
4 5 6
UP 1 2 3
LEFT RIGHT TAB 0 .
DN
----------------------------------------------------
|
META: Needs to be written.
6.1 Initialization 6.2 Menu variable access 6.3 Installing callbacks 6.4 The ticker interface 6.5 Display refreshing
menu points to the beginning of a binary menu image. bootmode is
one of COLD_BOOT or WARM_BOOT.
META: ...
Function `handler' installs function f at the location pointed to by fa. The return value contains the previous installed callback handler.
META: ...
META: ...
MEX has been written in Ansi-C. The prototype compiles with icc11 3.5 (68HC11) and gcc 2.7.2.1 (Unix, DOS). The program was mainly tested on a 68HC11 based embedded controller with small keyboard (23 keys) and 16x4 LC-display. The program size on the HC11 is about 14 kbytes. When all currently unimplemented features will be implemented, then the code-size is expected to be about 18 to 20 kbytes.
Porting MEX to another target/compiler in principle involves only an additional `#define' for the new compiler in `include/types.h' and some typedefs, also in `types.h'.
| [Top] | [Contents] | [Index] | [ ? ] |
There is one line component which is not editable. This is the `hfill' component.
| [Top] | [Contents] | [Index] | [ ? ] |
| [Top] | [Contents] | [Index] | [ ? ] |
1. Document History
2. Introduction
3. Menu Navigation
4. Line Navigation and Field Editing
5. Keyboard Layouts
6. Programming Interface
7. Implementation Notes
| [Top] | [Contents] | [Index] | [ ? ] |
| Button | Name | Go to | From 1.2.3 go to |
|---|---|---|---|
| [ < ] | Back | previous section in reading order | 1.2.2 |
| [ > ] | Forward | next section in reading order | 1.2.4 |
| [ << ] | FastBack | previous or up-and-previous section | 1.1 |
| [ Up ] | Up | up section | 1.2 |
| [ >> ] | FastForward | next or up-and-next section | 1.3 |
| [Top] | Top | cover (top) of document | |
| [Contents] | Contents | table of contents | |
| [Index] | Index | concept index | |
| [ ? ] | About | this page |