++ed by:
BASEBAND
Author image John Eaglesham

NAME

Device::XBee::API - Object-oriented Perl interface to Digi XBee module API mode.

EXAMPLE

A basic example:

 use Device::SerialPort;
 use Device::XBee::API;
 use Data::Dumper;
 $Data::Dumper::Useqq = 1;

 my $serial_port_device = Device::SerialPort->new( '/dev/ttyU0' ) || die $!;
 $serial_port_device->baudrate( 9600 );
 $serial_port_device->databits( 8 );
 $serial_port_device->stopbits( 1 );
 $serial_port_device->parity( 'none' );
 $serial_port_device->read_char_time( 0 );        # don't wait for each character
 $serial_port_device->read_const_time( 1000 );    # 1 second per unfulfilled "read" call

 my $api = Device::XBee::API->new( { fh => $serial_port_device } ) || die $!;
 if ( !$api->tx( { sh => 0, sl => 0 }, 'hello world!' ) ) {
     die "Transmit failed!";
 }
 my $rx = $api->rx();
 die Dumper( $rx );

SYNOPSIS

Device::XBee::API is a module designed to encapsulate the Digi XBee API in object-oriented Perl. This module expects to communicate with an XBee module using the API firmware via a serial (or serial over USB) device.

This module is currently a work in progress and thus the API may change in the future.

LICENSE

This module is licensed under the same terms as Perl itself.

CONSTANTS

A single set of constants, ':xbee_flags', can be imported. These constants all represent various XBee flags, such as packet types and broadcast addresses. See the XBee datasheet for details. The following constants are available:

 XBEE_API_TYPE__MODEM_STATUS
 XBEE_API_TYPE__AT_COMMAND
 XBEE_API_TYPE__AT_COMMAND_QUEUE_PARAMETER_VALUE
 XBEE_API_TYPE__AT_COMMAND_RESPONSE
 XBEE_API_TYPE__REMOTE_COMMAND_REQUEST
 XBEE_API_TYPE__REMOTE_COMMAND_RESPONSE
 XBEE_API_TYPE__ZIGBEE_TRANSMIT_REQUEST
 XBEE_API_TYPE__EXPLICIT_ADDRESSING_ZIGBEE_COMMAND_FRAME
 XBEE_API_TYPE__ZIGBEE_TRANSMIT_STATUS
 XBEE_API_TYPE__ZIGBEE_RECEIVE_PACKET
 XBEE_API_TYPE__ZIGBEE_EXPLICIT_RX_INDICATOR
 XBEE_API_TYPE__ZIGBEE_IO_DATA_SAMPLE_RX_INDICATOR
 XBEE_API_TYPE__XBEE_SENSOR_READ_INDICATOR_
 XBEE_API_TYPE__NODE_IDENTIFICATION_INDICATOR
 
 XBEE_API_BROADCAST_ADDR_H
 XBEE_API_BROADCAST_ADDR_L
 XBEE_API_BROADCAST_NA_UNKNOWN_ADDR
 
 XBEE_API_TYPE_TO_STRING
 XBEE_API_BAUD_RATE_TABLE

The above should be self explanatory (with the help of the datasheet). The constant "XBEE_API_TYPE_TO_STRING" is a hashref keyed by the numeric id of the packet type with the value being the constant name, to aid in debugging. The constant XBEE_API_BAUD_RATE_TABLE is the baud rate table used by the BD API command.

METHODS

new

Object constructor. Accepts a single parameter, a hashref of options. The following options are recognized:

fh

Required. The filehandle to be used to communicate with. This object can be a standard filehandle (that can be accessed via sysread() and syswrite()), or a Device::SerialPort object.

packet_timeout

Optional, defaults to 20. Amount of time (in seconds) to wait for a read to complete. Smaller values cause the module to wait less time for a packet to be received by the XBee module. Setting this value too low will cause timeouts to be reported in situations where the network is "slow".

When using standard filehandles, the timeout is implemented via select(). When using a Device::SerialPort object, the timeout is done via Device::SerialPort's read() method, and will expect the object to be configured with a read_char_time of 0 and a read_const_time of 1000.

node_forget_time

If a node has not been heard from in this time, it will be "forgotten" and removed from the list of known nodes. Defaults to one hour. See known_nodes for details.

auto_reuse_frame_id

All sent packets need a frame ID to uniquely identify them. There are only 254 available IDs and thus there can only be 254 outstanding commands sent to the XBee. Normally frame IDs will be freed and reused once a command reply is received, however there are scenarios where this can not be done (generally those that involve local or remote AT commands, sleeping/offline nodes, etc).

Normally, when no frame IDs are available but one is needed, the module will die with an error and the send attempt will be aborted. This condition could be trapped by the caller (via eval) to retry later, or could be treated as fatal.

With this flag set, instead of dieing, the oldest frame ID will be reused. This will help work around any issues with frame ID's "leaking", but could cause odd behavior in cases where all outstanding frame IDs are still in use. This option should be used with caution.

alloc_frame_id_func =head3 free_frame_id_func

Optional code references to functions used to allocate and free frame IDs. If both are specified they will be called in place of the internal frame ID tracking functions allowing the user more control over how frame IDs are generated. The alloc_frame_id_func will be called when a new frame ID is needed and will be passed as a parameter the reference to the Device:XBee::API object and must return an integer between 1 and 255 inclusive. The free_frame_id_func will be called when the reply frame is received and the frame ID is no longer needed and will be passed as parameters a reference to the Device::XBee::API obect and the frame ID to be freed.

See auto_reuse_frame_id for details on how this module uses frame IDs.

api_mode_escape

Optional. If set to a true value, the module will automatically escape outgoing data and un-escape incoming data for use with XBee API mode 2. Defaults to false.

See the XBee datasheet for details on API mode 2 and escaped characters.

at

Send an AT command to the module. Accepts two parameters, the first is the AT command name (as two-character string), and the second is the expected data for that command (if any). Data will be converted to a string before it is sent, so integers must first be packed before sending. See the XBee datasheet for a list of supported AT commands and expected data for each.

Returns the frame ID sent for this packet. This method does not wait for a reply from the XBee, as the expected reply is dependent on the AT command sent. To retrieve the reply (if any), call one of the rx methods.

If no reply is expected, the caller should immediately free the returned frame ID via free_frame_id to prevent frame ID leaks.

Example

my $at_frame_id = $api->at( 'AO', pack( 'C', 1 ) );

remote_at

Send an AT command to a remote module. Accepts three parameters: a hashref with endpoint addresses, command options, frame_id; the AT command name (as two-character string); and the third as the expected data for that command (if any) as a string. See the XBee datasheet for a list of supported AT commands and expected data for each.

Endpoint addresses should be specified as a hashref containing the following keys:

sh

The high 32-bits of the destination address.

sl

The low 32-bits of the destination address.

na

The destination network address.

apply_changes

If set, changes are applied immediately. If not set, an AT AC command must be sent separately before the changes will take effect.

Note: The following command options are not supported on all XBee devices.

disable_ack

If set, the remote node will not reply with an ack.

extended_xmit_timeout

If set, the exteded transmission timeout will be used.

Returns the frame ID sent for this packet. To retrieve the reply (if any), call one of the rx methods. If no reply is expected, the caller should immediately free the returned frame ID via free_frame_id to prevent frame ID leaks.

Example

The following example disables the blinking association light on the XBee with a constant on.

 if (
     !$api->remote_at(
         { sh => 1234567, sl => 1234567890, apply_changes => 1 },
         'D5', "\x1"
     )
 ) {
     die "Transmit failed!";
 }
 my $rx = $api->rx();
 warn Dumper( $rx );

tx

Sends a transmit request to the XBee. Accepts three parameters, the first is the endpoint address, the second is a scalar containing the data to be sent, and the third is an optional flag (known as the async flag) specifying whether or not the method should wait for an acknowledgement from the XBee.

Endpoint addresses should be specified as a hashref containing the following keys:

sh

The high 32-bits of the destination address.

sl

The low 32-bits of the destination address.

na

The destination network address. If this is not specified, it will default to XBEE_API_BROADCAST_NA_UNKNOWN_ADDR.

If both sh and sl are missing or the parameter is undefined,, they will default to XBEE_API_BROADCAST_ADDR_H and XBEE_API_BROADCAST_ADDR_L.

The meaning of these addresses can be found in the XBee datasheet. Note: In the future, a Device::XBee::API::Node object will be an acceptable parameter.

If the async flag is not set, the method will wait for an acknowledgement packet from the XBee. Return values depend on calling context. In scalar context, true or false will be returned representing transmission acknowledgement by the remote XBee device. In array context, the first return value is the delivery status (as set in the transmit status packet and documented in the datasheet), and the second is the actual transmit status packet (as a hashref) itself.

If the async flag is set, the method will not wait for an acknowledgement packet and the tx frame ID will be returned. The caller will need to then receive the transmit status packet (via one of the rx methods) and free the frame ID (via free_frame_id) manually.

No retransmissions will be attempted by this module, but the XBee device itself will likely attempt retransmissions as per its configuration (and subject to whether or not the packet was a "broadcast").

rx

Receives a packet from the XBee module. This packet may be a transmission from a remote XBee node or a control packet from the local XBee module.

If no packet is received before the timeout period expires, undef is returned.

Returned packets will be as a hashref of the packet data, broken out by key for easy access. Note, as this module is a work in progress, not every XBee packet type is supported. Callers should check the "api_type" key to determine the type of the received packet. When possible, packed integers will be unpacked into the "data_as_int" key. If no packed integer is found this key will not be present. If unpacking is not possible (due to an unknown packet type, etc), the value will be undef.

Accepts a single parameter, a flag indicating the received frame ID should NOT be freed automatically. See rx_frame_id for why you might want to use this flag (generally, cases when you expect multiple packets to arrive with the same frame ID).

rx_frame_id

Like rx but only returns the packet with the requested frame ID number and then frees that frame ID. If no packet with the specified frame ID is received within the object's configured packet_timeout time, undef will be returned. Any other packets received will be enqueued for later processing by another rx function call.

Accepts two parameters, the first being the desired frame ID and the second a flag denoting that the frame ID should NOT be automatically freed. In cases where multiple frames with the same ID are expected to be returned (such as after an AT ND command), it is preferable to set this flag to a true value and continue to call rx_frame_id until undef is returned, and then free the ID via free_frame_id.

discover_network

Performs a network node discovery via the ND 'AT' command. Blocks until no replies have been received in packet_timeout seconds.

node_info

known_nodes

Returns a hashref of all known nodes indexed by their full serial number (i.e. $node->{sh} . '_' . $node->{sl}). Nodes that haven't been heard from in the configured node_forget_time will be automatically removed from this list if they've not been heard from in that time. Nodes are added to that list when a message is received from them or a discover_network call has been made.

Note, the age-out mechanism may be susceptable to stepping of the system clock.

EXAMPLES

Miscellaneous code examples follow.

Fetch modem baud rage

 use Device::SerialPort;
 use Device::XBee::API;
 
 # From XBee datasheet pg 73.
 my @baud_rate_table = (
     1200,
     2400,
     4800,
     9600,
     19200,
     38400,
     57600,
     115200
 );
 
 # Configure the serial port
 my $serial_port_device = Device::SerialPort->new( '/dev/ttyU0' )
     || die $!;
 $serial_port_device->baudrate( 9600 );
 $serial_port_device->databits( 8 );
 $serial_port_device->stopbits( 1 );
 $serial_port_device->parity( 'none' );
 $serial_port_device->read_char_time( 0 );
 $serial_port_device->read_const_time( 1000 );
 
 # Create the API object
 my $api = Device::XBee::API->new( { fh => $serial_port_device } )
     || die $!;
 
 # Send the BD API command
 my $at_frame_id = $api->at( 'BD' );
 die "Transmit failed" unless $at_frame_id;
 
 # Receive the reply
 my $rx = $api->rx_frame_id( $at_frame_id );
 die "No reply received" if !$rx;
 if ( $rx->{status} != 0 ) {
     die "API error" if $rx->{is_error};
     die "Invalid command" if $rx->{is_invalid_command};
     die "Invalid parameter" if $rx->{is_invalid_parameter};
     die "Unknown error";
 }
 
 my $baud_rate = $baud_rate_table[ $rx->{data_as_int} ];
 if ( !$baud_rate ) {
     $baud_rate = $rx->{data_as_int};
 }
 
 print "Modem baud rate is $baud_rate bps.\n";

CHANGES

0.8, 20140914 - jeagle

Clean up remote_at function.

Improve error checking for invalid and empty packets.

0.7, 20130330 - jeagle

Add ability to allow users to specify their own frame allocation routines.

Update API mode 2 with latest version from jdodgen

0.6, 20120624 - jeagle

Update documentation.

Add support for API mode 2 escapes. Needs testing.

Add constant for the "BD" baud rate table.

0.5, 20120401 - jeagle

Add support for Win32::SerialPort to enable Windows support. (Thanks Jerry)

Fix issue with tx() in async mode. (Thanks Vicente)

Add support for "explicit rx indicator" packets. (Thanks Vicente)

0.4, 20110831 - jeagle

Fix packet timeout bug reported by Dave S.

Replace call to die() in __data_to_int with return undef, update docs to reflect this.

0.3, 20110621 - jeagle, jdodgen

Change from internal Device::SerialPort wrapper to accepting an fh.

Add asynchronous support to tx and add some helpful methods to support it.

Handle more command types (remote AT, ZigBee IO, node identification).

Add an option to re-use frame IDs under high tx load.

Many more changes!

0.2, 20101206 - jeagle

Initial release to CPAN.

1 POD Error

The following errors were encountered while parsing the POD:

Around line 534:

=back without =over