beautypg.com

Programming considerations, Syntax, Usage – Echelon I/O Model Reference for Smart Transceivers and Neuron Chips User Manual

Page 168

background image

158

Timer/Counter Output Models

Symbol Description

Minimum

Typical

Maximum

t

ret

Return from function

13 μs —

Programming Considerations

For edgedivide output, the data type of the output value for io_out( ) is an

unsigned long. Following reset of the Neuron Chip or Smart Transceiver, the
divider is disabled until the first call to the io_out( ) function. The first call to the

io_out( ) function for the edgedivide output model sets the output pin high and

starts the divider. When the divider is running, the function call to io_out( ) only
sets the value used for the divider and does not affect the state of the output pin.

However, when the output value is 0, the output signal is forced to a low state
and the divider is halted.

Syntax

pin

[output] edgedivide sync (

pin-nbr

) [invert]

io-object-name

[=

initial-output-level

];

pin

An I/O pin. Edgedivide output can specify pins IO_0 or IO_1. If IO_0 is
specified, the multiplexed timer/counter is used and the sync pin can be IO_4

through IO_7. If IO_1 is specified, the dedicated timer/counter is used and

the sync pin must be IO_4.

sync (

pin

-

nbr

)

Specifies the sync pin, which is the counting input signal. By default, the

divider counts negative edges.

invert

This keyword causes positive edges at the sync pin input to be counted rather
than the default negative edges.

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 can be 0

or 1. The default is 0.

Usage

unsigned long

output-value

;

io_out(

io-object-name

,

output-value

);