Calibre UK PICA93LV Benutzerhandbuch

Issue 1.3

 

Page 18

22/07/99

Example Usage:

(see also sample programs)

' This will write a byte of data to a slave previously addressed by sendaddress. */

Sub main

i2cdata$ = &H69

' Data byte which is to be transmitted */

i2cstatus$ = writebyte (i2cdata$)

if (i2cstatus and &H8000) = &H8000 then

print "Data has not been transmitted status is " + HEX$( i2cstatus%)

else

print "Data has been transmitted"

End If

End Sub

4.3.6.

Send an I2C Stop Routine

Function definition:

sendstop%()

Usage:

i2cstatus% = sendstop

Function:

procedure to send a Stop (end of communication signal) down the I2C Bus,
sending a transmission or reception with a slave which was address
previously by sendaddress.

Parameters are: 

None.

Value Returned:

i2cstatus%.

The value returned depends on whether the bus became free.

If the bus became free then the status (&H81) is returned.

If the bus does not became free then the last status read IORed with &H8000
will be returned.

The function will read the status a number of times, waiting for the bus to
become free, before returning an none free status - this number is defined by
the MAXNUMBEROFGOES constant defined in I2CINC.BAS, this value may
be altered to suit your system.

I2C status on exit:

The status of the Parallel I2C Communications Adapter will be &H81 - bus
idle and no unread / untransmitted data in data register.

Note - this may not be the case in a system where there is another master as
well as the Parallel I2C Communications Adapter, since this other master
may well have taken control of the bus by the time a program next uses
getstatus to read the status register.

(See Appendix A for details of status codes).

Example Usage:

(see also sample programs)

' This will write a Stop to the I2C Bus

sub main

i2cstatus = sendstop

print "Stop has been transmitted status is " + HEX$( i2cstatus%)

end sub