Conditional events, Complex events – Echelon Neuron C User Manual

Page 233

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Neuron C Reference Guide

213

parm-declaration

:

declaration-specifier-list

parm-declarator-list

;

parm-declarator-list

:

parm-declarator-list

,

declarator

declarator

Conditional Events

In Neuron C, an event is an expression which can evaluate to either TRUE or

FALSE. Neuron C extends the ANSI C concept of conditional expressions
through special built-in functions that test for the presence of special Neuron

firmware events. The Neuron C compiler has many useful built-in events that

cover all the common cases encountered in Neuron programming. However, a
Neuron C programmer can also create custom events by using any parenthesized

expression as an event, including one or more function calls, and so on.

when-event

:

( reset )

predefined-event

parenthesized-expr

interrupt-event

:

( repeating [,

frequency-value

] )

(

io-object-declarator

)

(

io-object-pin-name, interrupt-condition

)

predefined-event

:

( flush_completes )

( offline )

( online )

( wink )

(

complex-event

)

Complex Events

All of the predefined events shown above can be used not only in the

when-clause

portion of the task declaration but also in any general expression in executable

code. The complex events below use a function-call syntax, instead of the
keyword syntax of the special events above.

complex-event

:

io-event

message-event

net-var-event

timer-event

io-event

:

io_update_occurs (

variable-identifier

)

io_changes

(

variable-identifier

)

io_changes

(

variable-identifier

) by

shift-expr

io_changes

(

variable-identifier

) to

shift-expr

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