Echelon I/O Model Reference for Smart Transceivers and Neu Instrukcja Użytkownika Pobierz pdf (Strona 124)

114 Serial I/O Models

Table 45. SPI Slave Mode I/O Latency Values for Series 3100 Devices

Symbol Description Minimum Typical Maximum

Clock cycle (user specified) — — 1.25

Select low to Clock transition 220 μs — —

doc

Data out to Clock (1st bit of invert mode) 440 ns — —

cdo

Clock to data out — — 45 ns

dis

Data in setup 10 ns — —

dih

Data in hold 10 ns — —

sdz

Select high to data in high impedance — — 220 ns

Programming Considerations

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

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

functions are not disturbed by background interrupts. The SCI interrupt signal

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

by the application program.

The SPI 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 SPI interrupt.

To cancel an SPI operation currently in progress, use the spi_abort() function

rather than disabling interrupts.

Syntax

IO_8 spi master|slave [select(IO_7)] [clock(

const-expr

)] [invert]

[clockedge(+|-)] [neurowire]

io-object-name

;

master|slave

Determines whether the hardware is in master or slave mode. When using a

Neuron C device in SPI master mode, no other masters can be used in the

same bus.

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