Difference between revisions of "The Queue of Events"
From Hydrover
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Revision as of 11:24, 22 June 2017
Contents
Introduction
The queue of events is the queue where the system send events such as: input change, user action, encoder or transducer match, and from where the user's program get events to process and react to.
Structure of an Event
An event is defined in the library as an array of values:
[.opcode, .p0, .p1, .p2, .p3]
where:
-
.opcodeis used to uniquely identify the event type -
.p0, .p1, .p2, .p3contains informations specific to that event
Events' Library Functions
The library functions for events management are:
-
#define BASE_EVENT(%1) Event:%1[.opcode, .p0, .p1, .p2, .p3]is a macro to help in creating an event container -
SysEvEnable()enable the system to post events into the queue -
SysEvDisable()disable the system to post events into the queue -
EventGet( BASE_EVENT(ev) )get an event from the queue, if an event is not available will wait for -
EventSend( BASE_EVENT(ev) )send an event to the queue, can be used to inject custom and/or simulated events
Processing Events
In Event-driven programming the main loop of a program takes care of fetch, process and/or dispatch incoming events, the following code is an example of a minimal one.
/***************************************************************
*
* Minimal Event Processing Loop
*
* program.p
*
***************************************************************/
// include the library for H6105-D
//
#include <hydlib_cp>
// main function
//
main()
{
// clear display
//
dClear();
// select system font
//
dFont( system5x7 );
// place cursor
//
dCursor( 0, 0 );
// print on display
//
dPrintf("Processing Events");
// declare an event container
//
new BASE_EVENT(ev);
// enable system events
//
SysEvEnable();
// main loop
//
for( ;; )
{
// get new event from queue
//
EventGet( ev );
// process some events
//
switch( ev.opcode )
{
// <script stop> command from console
//
case SevEmergExit:
{
// exit main loop
//
break;
}
// push button activate
//
case SevDinActive:
{
if( ev.p0 == 0 )
{
dCursor( 0, 10 );
dPrintf("Button Pressed");
}
}
// push button deactivate
//
case SevDinInactive:
{
if( ev.p0 == 0 )
{
dCursor( 0, 10 );
dPrintf("Button Released");
}
}
}
}
// program end
}Type of Events
This are the system events, declared in the library
/* events codes */
const
{
SevEmergExit = 1, // receiving this event means that the program must stop execution
SevOnEnter, // the first event sent while entering a state
SevOnExit, // the last event sent while exiting a state
SevTick100mSec, // system tick sent at 100 (ms) rate
SevTick500mSec, // system tick sent at 500 (ms) rate
SevTickOneSec, // system tick sent at 1 (s) rate
SevTimerElapsed, // p0=timer number
SevEncCount, // p0=0, p1=1(count UP), p1=2(count DW)
SevDinChange, // p0= din number (0-19 = CP) (1000-1159 = IO) (2000-2159 = CA) (3000-3119 = CE)
SevDinActive, // p0= din number (0-19 = CP) (1000-1159 = IO) (2000-2159 = CA) (3000-3119 = CE)
SevDinInactive, // p0= din number (0-19 = CP) (1000-1159 = IO) (2000-2159 = CA) (3000-3119 = CE)
SevDinFastRel, // p0= din number (0-19 = CP) (3000-3119 = CE)
SevDinKeep, // p0= din number (0-19 = CP) (3000-3119 = CE)
SevAccMatch, // p0= acc number
SevAxisMoveDone, // p0= board number
SevAxisMoveAbort, // p0= board number p1= abort code ( 0= cil0 stalled max curr, 1= cil1 stalled max curr, 2= cil0 stop by cil1, 3= cil1 stop by cil0, 4= max delta )
SevCsDone, // p0= board number p1= pwm channel p2= cs number p3= step number
SevCsAbort, // p0= board number p1= pwm channel p2= cs number p3= step number
SevCsStep, // p0= board number p1= pwm channel p2= cs number p3= step number
SevMenuChange, // p0= return code of menu item selected
SevMenuClick, // p0= return code of menu item clicked
SevBareditChange, // no params
SevBareditExit, // no params
SevNumeditChange, // p0= numedit
SevNumeditExit, // p0= numedit, p1= exit code ( 0= cancel, 1= ok)
SevCmd, // p0,p1,p2,p3 came from command line eg:(script cmd 0 1 2 3)
SevCustom // opcode to use to feed in custom events
}