Echelon I/O Model Reference for Smart Transceivers and Neu Manual do Utilizador descarregar pdf (Página 110)

100 Serial I/O Models

START

STOP

Figure 36. SCI I/O and Timing

Programming Considerations

You can enable and disable SCI interrupts. For example, you can turn off

interrupts when going offline, or to assure that other time-critical application

functions are not disturbed by SCI interrupts. The SCI interrupt signal is used

by the firmware driver for the SCI I/O object. It is not directly accessible by the

application program.

The SCI interrupt is enabled by default. For Series 3100 devices, the io_idis()

function disables I/O interrupts. The function has the following signature:

void io_idis(void);

For Series 3100 devices, the io_iena() function enables I/O interrupts. The

function has the following signature:

void io_iena(void);

For Series 5000 devices, you cannot disable the SCI interrupt.

To cancel an SCI operation currently in progress, use the sci_abort() function

rather than disabling interrupts.

When using hardware SCI I/O, the Neuron C application must specify the clock

frequency that drives the on-chip SCI UART. To specify this frequency, the I/O

clock rate, use the following compiler directive:

#pragma specify_io_clock

clock-rate

The

clock-rate

value must be one of the following quoted strings: “20 MHz”, “10

MHz”, “6.5536 MHz”, “5 MHz”, or “2.5 MHz”. If the pragma-specified clock rate

does not match the Series 3100 physical clock frequency or the Series 5000

system clock rate, the Neuron Exporter component of the NodeBuilder FX

Development Tool reports an error to prevent generation of an incorrect

communications bit rate.

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Echelon I/O Model Reference for Smart Transceivers and Neu Manual do Utilizador Página 110