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I/O Model Reference 161

Syntax

[output] frequency [invert] [clock (

const-expr

)]

io-object-name

initial-

output-level

];

Specifies either pin IO_0 (using the multiplexed timer/counter) or IO_1 (using

the dedicated timer/counter).

invert

This keyword inverts the output for an output value of 0. The default output

for 0 is low.

clock (

const-expr

)

Specifies a clock in the range 0 to 7, where 0 represents the fastest clock and

7 represents the slowest clock. The default value is clock 0.

You can change resolution for the timer base clock frequency by calling the

io_set_clock( ) function with a clock value in the range 0..7 (using one of the

TCCLK_* macros defined in <echelon.h>). This function overrides the

resolution value specified for clock() within the I/O object declaration.

For an application running on a Series 5000 device, you can specify an

increased resolution for the timer base clock frequency by calling the

io_set_clock() function with a clock value in the range 0..15 (using one of the

TCCLK_* macros defined in <echelon.h>). This function overrides the

resolution value specified for clock() within the I/O object declaration.

See Appendix

Timer/Counter Periods and Resolution

, on page 187, for a

description of the timer resolution and maximum range for each specification

of the clock() value or each value of the TCCLK_* macros. See the

Neuron C

Reference Guide

for information about the io_set_clock() function.

io-object-name

A user-specified name for the I/O object, in the ANSI C format for variable

identifiers.

initial-output-level

A constant expression, in ANSI C format for initializers, used to set the state

of the output pin of the I/O object at initialization. The initial state is limited

to 0 or 1. The default is 0.

Usage

unsigned long

output-value

;

io_out(

io-object-name

output-value

);

Example

IO_1 output frequency clock(3) ioAlarm;

...

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