Echelon I/O Model Reference for Smart Transceivers and Neu Bedienungsanleitung PDF herunterladen (Seite 181)

I/O Model Reference 171

Example

IO_1 output pulsecount ioTrainOut;

when (...) {

// will produce 100 pulses on pin 1

// each pulse of period 6.554 milliseconds

io_out(ioTrainOut, 100);

}

Pulsewidth Output

For Series 3100 devices, the pulsewidth I/O model produces output pulses of a

specified period or duty cycle to create a repeating waveform whose duty cycle is

a function of

output-value

and whose period is a function of the clock period,

calculated as follows:

pulsewidth (ns) =

output-value

* 2000 * 2^(clock) / input_clock (MHz)

total_period (ns) = 256 * 2000 * 2^(clock) / input_clock (MHz)

where clock ranges from 0..7

For Series 5000 devices, the pulsewidth I/O model produces output pulses of a

specified period or duty cycle to create a repeating waveform whose duty cycle is

a function of

output-value

and whose period is a function of the clock period,

calculated as follows:

pulsewidth (ns) =

output-value

* 2000 * 2^(value) / 10 MHz

total_period (ns) = 256 * 2000 * 2^(value) / 10 MHz

where value ranges from 0..15

You can use this I/O object to implement digital-to-analog (D/A) converters or to

control any device with a pulsewidth-modulated input.

This model applies to Series 3100 Neuron Chips and Smart Transceivers, and to

Series 5000 Neuron Processors and Smart Transceivers.

Hardware Considerations

A timer/counter can be configured to generate a pulsewidth modulated repeating

waveform. In pulsewidth short function, the duty cycle ranges from 0% to 100%

(0/256 to 255/256) of a cycle, in steps of about 0.4% (1/256). See

Timer/Counter

Square Wave Output

on page 190 for the frequency of the waveform for various

clock values.

In pulsewidth long function, the duty cycle ranges from 0% to almost 100%

(0/65536 to 65535/65536) of a cycle in steps of 15.25 ppm (1/65536). See

Timer/Counter Pulsetrain Output

on page 193 for the frequency of the waveform

for various clock values. The asserted state of the waveform can be either logic

high or logic low. Writing a new pulsewidth value to the device takes effect at

the end of the current cycle. A pulsewidth modulated signal provides a simple

means of digital-to-analog conversion (see

Figure 64 on page 172).

The new output value does not take effect until the end of the current cycle, with

two exceptions:

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