ZBasicSysLib - page 223 of 361

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ZBasic System Library

ZBasic Microcontrollers

OpenX10(channel, inQueue, outQueue)

The X-10 communication channel to open.

The queue for incoming X-10 data.

The queue for outgoing X-10 data.

This subroutine prepares an X-10 communication channel for use. After the channel is opened you can

send arbitrary X-10 command bit streams, which you must create in low-level form, by simply adding the

constitutent bytes to the outgoing queue. Similarly, the incoming queue will receive raw X-10 data which

you must decode. Each X-10 command begins with the bit sequence 1110 which is followed by

additional bit pairs. The bit pair 01 represents a logic zero while the bit pair 10 represents a logic one.

The bit pair 11 is invalid and the bit pair 00 signifies the end of a command bit stream and also represents

the idle condition. Additional information on X-10 commands may be found in various places on the

If the specified channel is already open or if the channel number is invalid, the call has no effect. The

supported channel numbers are 1-2. The channel must have been previously configured by a call to

DefineX10(). Also, the queues specified for the receive and transmit channels each must have been

previously initialized by calling OpenQueue(). If you set up a transmit-only or receive-only serial channel

you may use the value 0 for the unused queue. If you provide the value 0 for both queues, the channel

will not be opened.

For three phase mode, additional queues may be specified for the transmit and receive operations on

phases 2 and 3 using SetQueueX10().

Dim outQueue(1 to 40) as Byte

Call OpenQueue(outQueue, SizeOf(outQueue))

Call DefineX10(1, 0, 12, &H08)

Call OpenX10(1, 0, outQueue)

The code above prepares channel 1 for transmit-only operation. If you wanted reception as well, you

would have to declare and initialize a second queue and define the receive pin.

X-10 communication requires the use of a zero-crossing signal input to the ZX as noted in the table

below. When one or more of the X-10 channels are open the zero-crossing input pin may not be used for

any other purpose. When all X-10 channels are closed, zero-crossing input pin will again be available for

other uses. Note, however, that the ability to await an external interrupt (e.g. INT0) on the zero-crossing

pin is unavailable when the low-level X-10 functionality is included in an application, even if the X-10

channel is closed.

For devices based on the ATtiny and ATmega chips, the default zero-crossing interrupt is INT0. If

desired, an alternate interrupt may be specified using the Option X10Interrupt directive described in the

ZBasic Language Reference Manual.