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Device::Dynamixel now uses a one-object-per-string model
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Dima Kogan committed Mar 1, 2011
1 parent 893c767 commit fb13593
Showing 1 changed file with 64 additions and 55 deletions.
119 changes: 64 additions & 55 deletions lib/Device/Dynamixel.pm
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Expand Up @@ -25,10 +25,11 @@ our $VERSION = '0.024';
open my $pipe, '+<', '/dev/ttyUSB0' or die "Couldn't open pipe for reading and writing";
my $dynamixel = Dynamixel->new($pipe, 5);
my $motorID = 5;
my $dynamixel = Dynamixel->new($pipe);
while(<>)
{
$dynamixel->moveMotorTo_deg($_);
$dynamixel->moveMotorTo_deg($motorID, $_);
}
=head1 DESCRIPTION
Expand All @@ -38,23 +39,28 @@ Dynamixel AX-12 motors have been tested to work with this module, but the others
should work also.
A daisy-chained series string of motors is connected to the host via a simple
serial connection. Each motor in the series has an 8-bit address. This address
is present in every command to address specific motors. The current
implementation of this module uses an object per motor, NOT an object per string
of motors. This may change in the future.
serial connection. Each motor in the series has an 8-bit ID. This ID is present
in every command to address specific motors. One Device::Dynamixel object should
be created for a single string of motors connected to one motor port.
These motors communicate using a particular protocol, which is implemented by
this module. Commands are sent to the motor. A STATUS reply is sent back after
this module. Commands are sent to the motor. A B<STATUS> reply is sent back after
each command. This module handles construction and parsing of Dynamixel packets,
as well as the sending and receiving data when needed.
=head2 VARIABLES
The dynamixel broadcast address is accessible as
$Device::Dynamixel::BROADCAST_ADDR. The addresses of Dynamixel control registers
are available as %Device::Dynamixel::addresses. This allows the application to
send arbitrary commands to the motor. For example, to set the moving speed of
the motor to 100%:
The communicate with all motor at once, send commands to the broadcast ID:
$Device::Dynamixel::BROADCAST_ID.
The addresses of Dynamixel control registers
are available as
%Device::Dynamixel::addresses.
This allows the application to send arbitrary commands to the motor. For
example, to set the moving speed of the motor to 100%:
$dynamixel->writeMotor($Device::Dynamixel::addresses{Moving_Speed_L},
[0xFF, 0x03]); # 0x3FF is the top speed for the
Expand All @@ -63,10 +69,8 @@ the motor to 100%:
=cut




# Constants defined in the dynamixel docs
const our $BROADCAST_ADDR => 0xFE;
const our $BROADCAST_ID => 0xFE;
const my %instructions =>
(PING => 0x01,
READ_DATA => 0x02,
Expand Down Expand Up @@ -146,18 +150,17 @@ const my $motorRange_deg => 300;

=head1 CONSTRUCTOR
=head2 new(PIPE, MOTORADDRESS)
=head2 new(PIPE)
Creates a new object to talk to a Dynamixel motor. The file handle has to be opened and set-up
prior to constructing the object.
=cut
sub new
{
my ($classname, $pipe, $motoraddr) = @_;
my ($classname, $pipe) = @_;

my $this = {pipe => $pipe,
addr => $motoraddr};
my $this = {pipe => $pipe};
bless($this, $classname);

return $this;
Expand All @@ -167,7 +170,7 @@ sub new
sub _makeInstructionPacket
{
my ($motorID, $instruction, $parameters) = @_;
my $body = pack( 'C3C' . @$parameters,
my $body = pack( 'C3C' . scalar @$parameters,
$motorID, 2 + @$parameters, $instruction,
@$parameters );

Expand Down Expand Up @@ -214,10 +217,12 @@ Sends a ping. STATUS reply is returned

sub pingMotor
{
my $this = shift;
my ($pipe, $motorID) = @{$this}{qw(pipe motorID)};
my $this = shift;
my ($motorID) = @_;

my $pipe = $this->{pipe};
print $pipe _makeInstructionPacket($motorID, $instructions{PING}, []);
return pullMotorReply($pipe);
return pullMotorReply($this->{pipe});
}

=head2 writeMotor(startingAddress, data)
Expand All @@ -228,10 +233,12 @@ Sends a command to the motor. STATUS reply is returned.

sub writeMotor
{
my ($this, $where, $what) = @_;
my ($pipe, $motorID) = @{$this}{qw(pipe motorID)};
my $this = shift;
my ($motorID, $where, $what) = @_;

my $pipe = $this->{pipe};
print $pipe _makeInstructionPacket($motorID, $instructions{WRITE_DATA}, [$where, @$what]);
return pullMotorReply($pipe);
return pullMotorReply($this->{pipe});
}

=head2 readMotor(startingAddress, howManyBytes)
Expand All @@ -242,10 +249,12 @@ Reads data from the motor. STATUS reply is returned.

sub readMotor
{
my ($this, $where, $howmany) = @_;
my ($pipe, $motorID) = @{$this}{qw(pipe motorID)};
my $this = shift;
my ($motorID, $where, $howmany) = @_;

my $pipe = $this->{pipe};
print $pipe _makeInstructionPacket($motorID, $instructions{READ_DATA}, [$where, $howmany]);
return pullMotorReply($pipe);
return pullMotorReply($this->{pipe});
}

=head2 writeMotor_queue(startingAddress, data)
Expand All @@ -257,10 +266,12 @@ not actually execute the command until triggered with triggerMotorQueue( )

sub writeMotor_queue
{
my ($this, $where, $what) = @_;
my ($pipe, $motorID) = @{$this}{qw(pipe motorID)};
my $this = shift;
my ($motorID, $where, $what) = @_;

my $pipe = $this->{pipe};
print $pipe _makeInstructionPacket($motorID, $instructions{REG_WRITE}, [$where, @$what]);
return pullMotorReply($pipe);
return pullMotorReply($this->{pipe});
}

=head2 triggerMotorQueue( )
Expand All @@ -271,10 +282,12 @@ Sends a trigger for the queued commands. STATUS reply is returned.

sub triggerMotorQueue
{
my $this = shift;
my ($pipe, $motorID) = @{$this}{qw(pipe motorID)};
my $this = shift;
my ($motorID) = @_;

my $pipe = $this->{pipe};
print $pipe _makeInstructionPacket($motorID, $instructions{ACTION}, []);
return pullMotorReply($pipe);
return pullMotorReply($this->{pipe});
}

=head2 resetMotor( )
Expand All @@ -285,10 +298,12 @@ Sends a motor reset. STATUS reply is returned.

sub resetMotor
{
my $this = shift;
my ($pipe, $motorID) = @{$this}{qw(pipe motorID)};
my $this = shift;
my ($motorID) = @_;

my $pipe = $this->{pipe};
print $pipe _makeInstructionPacket($motorID, $instructions{RESET}, []);
return pullMotorReply($pipe);
return pullMotorReply($this->{pipe});
}

=head2 syncWriteMotor(startingAddress, data)
Expand All @@ -299,8 +314,8 @@ Sends a synced-write command to the motor. STATUS reply is returned.

sub syncWriteMotor
{
my ($this, $writes, $where) = @_;
my ($pipe, $motorID) = @{$this}{qw(pipe motorID)};
my $this = shift;
my ($motorID, $writes, $where) = @_;

my @parms = map { ($_->{motorID}, @{$_->{what}}) } @$writes;
my $lenchunk = scalar @{$writes->[0]{what}};
Expand All @@ -311,8 +326,9 @@ sub syncWriteMotor
die "syncWriteMotor: size mismatch!";
}

print $pipe _makeInstructionPacket($BROADCAST_ADDR, $instructions{SYNC_WRITE}, \@parms);
return pullMotorReply($pipe);
my $pipe = $this->{pipe};
print $pipe _makeInstructionPacket($BROADCAST_ID, $instructions{SYNC_WRITE}, \@parms);
return pullMotorReply($this->{pipe});
}

=head2 pullMotorReply( )
Expand Down Expand Up @@ -354,13 +370,13 @@ particular position

sub moveMotorTo_deg
{
my $this = shift;
my $position_deg = shift;
my $this = shift;
my ($motorID, $position_deg) = @_;

my $position = int( 0.5 + ($position_deg * $motorRange_coords/$motorRange_deg + 0x1ff) );
$position = 0 if $position < 0;
$position = $motorRange_coords-1 if $position >= $motorRange_coords;
return $this->writeMotor($addresses{Goal_Position_L}, [unpack('C2', pack('v', $position))] );
return $this->writeMotor($motorID, $addresses{Goal_Position_L}, [unpack('C2', pack('v', $position))] );
}

1;
Expand All @@ -371,16 +387,9 @@ __END__
=head1 BUGS
There are several aspects of this module that are unideal and may change in the
future. The current implementation ties an instance of a Device::Dynamixel
object to a particular motor, NOT to a string of motors. This means that talking
to multiple motors requires multiple instances. This imposes a requirement that
only one motor can be controlled at any given time. Further, multi-motor
commands like syncWriteMotor( ) become essentially useless.
Another major issue is the baud rate of the serial communication. The motors
default to 1M baud. This is unsupported by the stock POSIX module in perl5, so
the serial port must be configured external to this module.
An issue is the baud rate of the serial communication. The motors default to 1M
baud. This is unsupported by the stock POSIX module in perl5, so the serial port
must be configured external to this module.
=head1 REPOSITORY
Expand Down

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