richrd / nxt-python Goto Github PK

I have attached a patch that provides the methods for the hitechnic
gyro sensor. I haven't had time to add the calibration function yet but I
hope to do that in a couple days. 

this is the description included in the class header

#This class is for the hitechnic gryo accelerometer. When the gryo is
#not moving there will be a constant offset that will change with
#temperature and other ambient factors. It might be appropriate to
#write a calibration function to account for this offset.
#
#TODO:calibration

Hey guys,

I've just been reading through the sensor.py code (current trunk). I might've 
spotted a way to reduce the number of direct commands necessary to retrieve a 
sample from a digital sensor. In Bluetooth connections (which are fairly slow 
as you probably know), this can sometimes/often save one out of 3 direct 
commands and reduce the time to query a digital sensor by roughly 30ms.

I'm not sure if I understood the whole nxt-python package correctly, but I 
assume that all sample retrieval communication with digital sensors is 
happening through the method "i2c_query()" from the class DigitalSensor (here: 
http://code.google.com/p/nxt-python/source/browse/trunk/nxt/sensor.py#128 ). If 
that's correct, then in line 135, _ls_get_status() get's called, which seems to 
do busy waiting until the I2C bus / the sensor has finished its current 
operation. Only when enough bytes are ready (or in case of a timeout), the 
polling (direct command LSGetStatus) will stop.

Now the point: If LSGetStatus tells you "everything ok, data ready to be 
retrieved", you have to issue the direct command LSRead. This is where you can 
save time. You can totally ignore the LSGetStatus commands, and allways try 
LSRead straight away. As long as there isn't enough data, you can detect this 
situation from the status byte of the reply package. But if you're lucky, i.e. 
once the sensor is ready, you already got the valid data as payload. In summary 
this saves 1 command.

We've been using this method for a long time successfully, and it did greatly 
improve the performance with all digital sensors (the US being most widely 
used).

An implementation example with further explanations and some statusbyte-codes 
can be found here:
http://www.mindstorms.rwth-aachen.de/trac/browser/tags/version-4.03/RWTHMindstor
msNXT/COM_ReadI2C.m#L139


I'd love to see you guys use that principle and see if you can improve your 
Bluetooth performance. If not that's fine, but you could keep this in mind and 
maybe on the to-do-list.
Thanks for reading.

Regards, Linus

I have attached a patch that provides the methods for the new lego NXT
color sensor. I haven't had time to add the calibration function yet but I
hope to do that in a couple days. 


this is the description included in the class header

# this is a class for the lego NXT 2.0 RGB color sensor
# not to be confused with the hitechnic color sensor
# the color sensor can run in two modes:
# a light sensor which returns the reflected light from the lamp that is
# currently on (red, green, blue, off/ambient) on a scale of 1-1023
# a color sensor that returns a 1-6 decimal value corresponding to
# (black, blue, green, yellow, red, white) unfortunately the RGB values
# are not sent over the wire

# TODO: calibration 

#note: if you create a new object everytime you make a call the light 
# will flash on an off because each time the object is created the light
# color is set to  none

Describe the new feature more precisely.
(Not sure, if this makes sense, and how much effort it would take to implement.)

I would like to have an API like this:

    brick.startRecord(keepRunning)
    [...]
    prog = brick.stopRecord()
    brick.upload(prog, "foo")
    brick.run("foo")

`keepRunning` = False would only record all commands, but not execute them.

Why do you think it's important?
I used NXT-Python to drive a logo-'turtle'. This means mainly sending a 
sequence of forward(10) - left(90) - pendown() - ...

When controlling the robot, we need a USB cable which is uncomfortable, or 
bluetooth which is not always available (and uses batterie and is less 
accurate?)

Any ideas on how to implement it?
If a program is only a list of telegrams as they are currently generated and 
sent to the brick, then it may be possible to simply buffer them?
If not, then I guess its probably not worth the effort.
Also, this would not allow to react on sensors, but there are use cases where a 
simple play-back would be nice.

Please provide any additional information below.

After performing some tests I noticed that the loop time from data requested to 
data received for a sensor with USB is ~10-20ms but with bluetooth it is 
~100-150ms . This doesn't seem correct. Bluetooth can transmit and receive data 
much faster than this.  

I am working through trying to use python to run my NXT (Lejos is currently 
what is running on the NXT) but am just starting out. Please forgive the basic 
question, but what firmware do I need to start with?

I am on Windows XP using the nxt-python 2.2.0

Describe the new feature more precisely.
Uploading the package to PyPI would allow simple installation for those that 
have EasyInstall running:

$sudo easy_install nxt-python


Any ideas on how to implement it?
Add 'register upload' to the command line when calling setup.py sdist

Describe the new feature more precisely.

Currently the Method() backend selection needs to be specified for
find_one_brick().

It should be specified either via configuration parameters or at the beginning 
of the program.

Why do you think it's important?

Easy to modify / change backend without touching other code.

Any ideas on how to implement it?

Configure file, command line parameter, configuration method at begnning of 
program.

Please provide any additional information below.

here is a stack trace:

    sensor = Ultrasonic( BRICK, inPort)
  File "nxt-my\nxt\sensor\generic.py", line 95, in __init__
    super(Ultrasonic, self).__init__(brick, port, check_compatible)
  File "nxt-my\nxt\sensor\digital.py", line 73, in __init__
    sensor = self.get_sensor_info()
  File "nxt-my\nxt\sensor\digital.py", line 156, in get_sensor_info
    version = self.read_value('version')[0].split('\0')[0]
  File "nxt-my\nxt\sensor\digital.py", line 143, in read_value
    raise I2CError, "read_value timeout"

this is with Mindstorm 1.0 and  nxt-python-2.2.1 on Windows-7, brick is 
connected via USB

The problem seems to go away if I insert a 10 ms delay between i2c write and 
read in _i2c_query in sensor/digital.py

        self.brick.ls_write(self.port, msg, n_bytes)
        sleep(0.01)
        try:
            self._ls_get_status(n_bytes)


If I skip the version check, I can still use the sensor without the delay. (but 
get_sensor_info() still does not work).


A similar problem happens when trying to get info from hitechnic color sensor. 
get_sensor_info() times out...

But if I skip the version check, then I get a timeout when trying to retrieve 
color information.. 

Inserting a delay of 15ms solves the problem..


And the last tidbit: if I initialize the color sensor as Ultrasonic one and 
skip the version check, then get_distance() works even without delay.

I found that there is an indentation problem at the definition of method:

def reset_position(self, relative):

inside the file motor.py

Thank you!

What steps will reproduce the problem?
1. compass = hitechnic.Compass(brick, sensor.PORT_2)
2. compass.get_heading()
3. compass.set_mode(compass.Modes.CALIBRATE)

What is the expected output? What do you see instead?
Heading in degrees from North. An incorrect value is returned instead. So I 
tried to calibrate the compass, and got the following exception:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "nxt/sensor/hitechnic.py", line 85, in set_mode
    if mode != CompassMode.MEASUREMENT and \
NameError: global name 'CompassMode' is not defined


What version of nxt-python are you using? On what operating system?
revision 277 on Ubuntu 10.10


Please provide any additional information below.
Before calibrating the compass, I modified Compass.get_heading() to use the two 
degree heading and adder instead of the low byte from register 0x44 (which 
didn't appear to fully correspond with the spec).

Upon attempting to calibrate the compass, I discovered another bug, resulting 
in the above exception. I also fixed this. I'm unsure if the original 
get_heading() method would work now as well, but the modified method tests out 
ok, so I suggest sticking with it. 

Describe the new feature more precisely.

I have an NXT (v1) Lego set. I am recently begun learning Python. I want to
use the software you are developing. I have installed the software on my
laptop. Now what?

I would like some very basic, even condescending documentation, on how to
use this software -- perhaps an example or two with step-by-step
instructions on how to implement them would be helpful.


Why do you think it's important?

Lowering the barrier for entry will enable an increase in popularity which
should in turn result in a) people helping you with the project, and b)
people telling you how great you are for developing the project and sharing
your efforts with all of us -- it is nice to be appreciated.


Any ideas on how to implement it?

Ask someone who knows considerably less than you to try out this software;
whenever they say "What do I do now?" respond to them via the project wiki : )

To include the Hitechnic Tetrix controller for the NXT DC and servo controller 
form Hitechnic




Why do you think it's important?

the exposure of Tetrix/NXT make the next level of robot enthusiasts, and with 
the addition of ROS and other ROS nodes will make the NXT/Tetrix a suitable 
platform to do basic research in robotics

Any ideas on how to implement it?

I don't have to much experience in this implementation that's why I'm asking 
your help

Thanks

Please provide any additional information below.

What steps will reproduce the problem?
1. Attempt to instantiate nxt.sensor.hitechnic.EOPD:
     import nxt
     from nxt import sensor
     from nxt.sensor import hitechnic

     brick = nxt.find_one_brick()
     laser = hitechnic.EOPD(brick, sensor.PORT_3)

What is the expected output? What do you see instead?
An EOPD object should be created; instead, the following exception is raised:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "nxt/sensor/hitechnic.py", line 245, in __init__
    super(Light, self).__init__(brick, port)
NameError: global name 'Light' is not defined


What version of nxt-python are you using? On what operating system?
I'm using nxt-python version 2.0.1 on Ubuntu 10.10 64-bit. I also tested the 
latest source code from the Subversion repo (revision 273), with the same 
result.

Instead of the server module accepting string instructions, there shouldbe a 
modified brick class that does all the communication. Essentially, if you 
wanted to use an nxt on the server, you would create the 
locator.get_network_brick() class instead of locator.find_one_brick(). Then, 
functions linked to the network_brick class would simply be a server 
implementation of the methods.

Another way to do this by transferring strings would be to transfer the 
commands in python syntax as a string.

Hi,
I'm just an nxt beginner, so I just tried the examples.
Everything is ok, I just felt like contributing some minor pythonistic 
enhancements to the mary.py example.
I introduced a loop that makes this file less verbose.

See the attached patch.

What steps will reproduce the problem?
1. Run nxt_test with fantom backend
2. Correct output is returned
3. Re-run nxt_test with fantom backend
4. nxt_test aborts with Fantom error

What is the expected output? What do you see instead?
Multiple sequential runs of nxt_test to return correct output.

This is due to a missing b.sock.close() for the normal execution case.
(proposed patch enclosed). I think the other scripts might also be similarly 
impacted but I didn't test them.


Index: nxt_test
===================================================================
--- nxt_test    (revision 364)
+++ nxt_test    (working copy)
@@ -24,6 +24,7 @@
     print 'Firmware version %s.%s' % fw_version
     millivolts = b.get_battery_level()
     print 'Battery level %s mV' % millivolts
+    b.sock.close()
 except:
     print "Error while running test:"
     traceback.print_tb(sys.exc_info()[2])

I attempted to run the examples after having installed python2.6, 
nxt-python-2.2.0, and pyUSB on my laptop (Windows 7 if that makes a 
difference). I installed those and tried running the examples, starting with 
spin.py.

When I try to connect to the brick using USB I get the "No back end" error. 
"USB module unavailable, not searching there Bluetooth module unavailable, not 
searching there".

 I saw that there is a warning with the USB connection being buggy, so I purchased a bluetooth adapter for my laptop and installed it. I am able to pair with the brick via bluetooth, but when I run spin.py I get a different error, "USB module unavailable, not searching there". No longer does it mention Bluetooth being unavailable. And at the bottom it reads "BrickNotFoundError" 

Any help? Thank you very much!

(appologies for not copy-pasting the exact errors but I am typing this from a 
different machine as my laptop does not have internet at this moment). 

Please relicense python-nxt to the LGPL because if it is gpl devlepoers are 
forced to license their software GPL and cant combine gpl-incompatible software 
with python-nxt

What steps will reproduce the problem?
1. Connect an NXT with USB.
2. Read Identification information from sensor.

What is the expected output? What do you see instead?
It should be like this:
Version: `V1.0`
0x56, 0x31, 0x2e, 0x30, 
Product ID: `LEGO`
0x4c, 0x45, 0x47, 0x4f, 
Type: `Sonar`
0x53, 0x6f, 0x6e, 0x61, 0x72, 
But instead is like this:
Version: `Sonar`
0x53, 0x6f, 0x6e, 0x61, 0x72, 
Product ID: `V1.0`
0x56, 0x31, 0x2e, 0x30, 
Type: `LEGO`
0x4c, 0x45, 0x47, 0x4f, 
As you can see, the version is replaced with the type, the manufacturer with 
the version and the type with the manufacturer. It is as if each one is shifted 
8 registers down and the last one is looped back to register 0. Why the heck is 
this happening?

Please use labels and text to provide additional information.
The only explanation I can think of is that there is less latency when using 
USB, but adding gaps in various places doesn't do anything.

Could someone on Windows or Mac please test this and see if it's everywhere or 
just Linux?

What steps will reproduce the problem?
1. Install nxt-python
2. Install pyUSB
3. Attempt to run file from examples folder

What is the expected output? What do you see instead?
The expected output would be to successfully run the file (Ex: mary.py).  
However, with all files, I receive the following output:

Host: 54:32:59:92:F9:39 Name: MyNXT Strict: True
USB: True BT: False Fantom: False FUSB: False FBT: False
Traceback (most recent call last):
  File "C:\Users\Student\Downloads\nxt-python-2.2.1 (1)\nxt-python-2.2.1\examples\mary.py", line 15, in <module>
    b = nxt.locator.find_one_brick(debug=True)
  File "C:\Python26\lib\site-packages\nxt\locator.py", line 137, in find_one_brick
    raise BrickNotFoundError
BrickNotFoundError

(This is with passing debug=True)

What version of nxt-python are you using? On what operating system?
2.2.1, Windows 7

I realize it was stated using USB is buggy, but I would like to continue trying 
to use it.

Hi,
I'm just an nxt beginner, so I just tried the examples.
Everything is ok, I just felt like contributing some minor formatting issues in 
the example files.

I added some «#/usr/bin/env python» and

#comment

is now

# Comment.

See the attached patch.

What steps will reproduce the problem?
1. Examine the code.
2. Look at nxt/fantomsock.py line 46
3. See that it says: paired_addr = pair_bluetooth(addr)
4. Look for where pair_bluetooth is defined

What is the expected output? What do you see instead?

I would expect to find the function defined, but I don't.  It turns out 
pyfantom has such a function, so I think this is meant to be 
pyfantom.pair_bluetooth.

What version of nxt-python are you using? On what operating system?

Version is 2.2.1.  O/S is Linux (so this file isn't actually used).  The error 
was detected through an automated test.

What steps will reproduce the problem?
1. in motcont, ports 3 4 and 5 refer to multiple motors and if one activates 
them, the "interval" is tracked for such port rather than for the motors 
individually
2. so if one gives a command to ports 3, 4 or 5 and immediately after sends a 
command to a single motor, the pause that motcont needs for that motor is not 
enforced.
3. also, it would be more elegant/integrated in NXT-Python to use PORT_A + 
PORT_B + PORT_B (which is "7") instead of "5" when giving orders to multiple 
motors.


What is the expected output? What do you see instead?


What version of nxt-python are you using? On what operating system?


Please provide any additional information below.

It would be nice to have a driver-like socket interface function, meaning 
that it would be easily usable over networks and different programming 
languages.

It would use a command-type interface. Example:

<python>

import socket
com = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
com.bind(('localhost', 98712))
com.connect()
com.send('find_brick') #connect to brick command, this would cause the 
driver to do x = find_one_brick()
rslt = com.recv(1) #get return code
if rslt != 0:
   print 'no brick found.'
   exit(1)
com.send('get_light_sample') #would trigger a get_sample() routine
dist = com.recv(10)
print dist
com.send('close_brick_sock') #would trigger brick's close() command
com.close()

</python>

There would be many commands, including 'kill_server', to be called when 
the server has done its job.

To start the server, one would use, in a separate program:

<python>

import nxt.server
nxt.server.serve_forever()

</python>

I'll see what I can do to get started on this, it might take a while 
because of socket and thread things. However, a single-thread server will 
robably be relatively easy.

Oops! Looks like that last revision generated another bug.

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "nxt/__init__.py", line 17, in <module>
    from .sensor import *
  File "nxt/sensor/__init__.py", line 32, in <module>
    import hitechnic
  File "nxt/sensor/hitechnic.py", line 244
    from math import sqrt

Attached is a Subversion patch.

When I run the CNC example, it finds the brick over bluetooth and connects, but 
the motors never spin. and I get about 2000 lines that look like this.

2011-04-08 15:31:57.844 Python[57997:7307] *** __NSAutoreleaseNoPool(): Object 
0x103c89ac0 of class __NSCFDate autoreleased with no pool in place - just 
leaking

The program stops after 4 seconds like it's supposed to.

What version of nxt-python are you using?
  The latest SVN checkout

On what operating system?
  Mac 10.6.6

My robotics group has been using RobotC for a long time, so we got HiTechnic 
motors to make our robot faster. However, I want to use python but can not find 
a way, in nxt-python to use our HiTechnic motors. I found nxt.sensors.hitechnic 
but it isn't a sensor?

If there is a way to get HiTechnic motors to work, can I see an example? Our 
motors are attached to PORT_1 (and only that, that's why I don't get to use it 
from the examples haha)

What steps will reproduce the problem?
1. I have tried to import the file "tiltedtwister.rxe" ( 
http://tiltedtwister.com/download/tt2/tiltedtwister.zip ) on nxt 2.0
2. I use the command py-t2n -put tiltedtwister.rxe on ubuntu.

What is the expected output? What do you see instead?

This fails, and I obtain:
 --------------------------------------------------------------------
 >$ py-t2n -put tiltedtwister.rxe

 Unexpected error
 Traceback (most recent call last):
 File "/usr/local/bin/py-t2n", line 99, in
 put(b, f)
 File "/usr/local/bin/py-t2n", line 67, in put
 w = FileWriter(b, fname, len(data))
 File "/usr/local/lib/python2.7/dist-packages/nxt/brick.py", line 150, in __init__
 self.handle = self.brick.open_write(fname, size)
 File "/usr/local/lib/python2.7/dist-packages/nxt/brick.py", line 31, in poll
 return parse_func(igram)
 File "/usr/local/lib/python2.7/dist-packages/nxt/system.py", line 47, in _parse_open_write
 tgram.check_status()
 File "/usr/local/lib/python2.7/dist-packages/nxt/telegram.py", line 114, in check_status
 nxt.error.check_status(self.parse_u8())
 File "/usr/local/lib/python2.7/dist-packages/nxt/error.py", line 85, in check_status
 raise ex
 nxt.error.SysProtError: No space
 Exception AttributeError: "'FileWriter' object has no attribute 'handle'" in > ignored

 ---------------------------------------------------------------------------------

Additional remarks:

1) I have imported several files with extension .rxe  with similar size on the 
brick and this works.
2) I have suppress some files from nxt to make more space (as suggested by the 
last line "nxt.error.SysProtError: No space"... but no way.

thank you in advance for your help

with best regards

jgl

What steps will reproduce the problem?
1. instantiate EOPD object
2. call EOPD.get_processed_value()

What is the expected output? What do you see instead?
A value that scales linearly as the distance from the target changes is 
expected. An erratic or unchanging value is returned instead.

What version of nxt-python are you using? On what operating system?
Revision 275 on Ubuntu 10.10

Please provide any additional information below.
I've attached a Subversion patch. 

What steps will reproduce the problem?
1. install libusb-win32 (on 32-bit or 64-bit Windows)
2. try to connect to NXT
3. connection fails because usb device is unconfigured

What version of nxt-python are you using? On what operating system?
nxt-python 2.2.0 on Win7 x64

Please provide any additional information below.

patch for usbsock.py:
>import os
...
def connect(self):
  ...
  >if os.name != 'nt':
    self.handle.reset()


see http://sourceforge.net/apps/trac/libusb-win32/wiki/libusbwin32_documentation
usb_reset() ... "Causes re-enumeration: After calling usb_reset, the device 
will need to re-enumerate and thus requires you to find the new device and open 
a new handle. The handle used to call usb_reset() will no longer work."

I had trouble getting BlueTooth to work on OS X 10.8 because it seems that none 
of the bluetooth libraries are supported any more.  However, I noticed that 
when I paired my NXT with my Mac it created a device file corresponding to the 
bluetooth serial port.  I whipped up a simple 'socket' class to communicate via 
the device file, and it seems to work.  By default it searches for the first 
device that matches the pattern "/dev/*-DevB" because mine came up as 
"/dev/<BrickName>-DevB"; not sure if that's standard or not.  Anyway, the patch 
is here:

https://github.com/dgchurchill/nxt-python/commit/d3573d36c18064e6250833967c53694
494068456.patch

Cheers,
Dave

What steps will reproduce the problem?
1.import nxt

What is the expected output? What do you see instead?
Expected Output:

Instead:
SyntaxError

What version of nxt-python are you using? On what operating system?
I am using version 2.0.1 on Mac OSX G4 with Bluetooth.

Please provide any additional information below.
I think you would have to do this code:

try:
   import nxt
except SyntaxError:
   import nxt

As you may have figured out, it doesn't work if you do it one time but it does 
if you do it 2 times.

What steps will reproduce the problem?
1. Run test_sensors.py
2. See crash
{{{
$python test_sensors.py 
Touch: no
Light: 1023
Ultrasonic:
Traceback (most recent call last):
  File "test_sensors.py", line 20, in <module>
    test_sensors(sock.connect())
  File "test_sensors.py", line 16, in test_sensors
    print 'Ultrasonic:', UltrasonicSensor(b, PORT_3).get_sample()
  File "/u/tfoote/nxt_devel/nxt/nxt_python/src/nxt/sensor.py", line 262, in 
get_sample
    return self.get_measurement_byte_0()
  File "/u/tfoote/nxt_devel/nxt/nxt_python/src/nxt/sensor.py", line 79, in 
query
    data = self.i2c_query(address, n_bytes)
  File "/u/tfoote/nxt_devel/nxt/nxt_python/src/nxt/sensor.py", line 122, in 
i2c_query
    self.brick.ls_write(self.port, msg, n_bytes)
  File "/u/tfoote/nxt_devel/nxt/nxt_python/src/nxt/brick.py", line 24, in 
poll
    return parse_func(igram)
  File "/u/tfoote/nxt_devel/nxt/nxt_python/src/nxt/direct.py", line 28, in 
_parse_simple
    tgram.check_status()
  File "/u/tfoote/nxt_devel/nxt/nxt_python/src/nxt/telegram.py", line 112, 
in check_status
    nxt.error.check_status(self.parse_u8())
  File "/u/tfoote/nxt_devel/nxt/nxt_python/src/nxt/error.py", line 85, in 
check_status
    raise ex
nxt.error.I2CError: Specified channel/connection not configured or busy
}}}

What is the expected output? What do you see instead?
{{{
$python test_sensors.py 
Touch: no
Light: 1023
Ultrasonic: 7
}}}

What version of the product are you using? On what operating system?
This nxt-python-1.1.1  on Ubuntu Karmic64

Please provide any additional information below.
Doing some research it seems that there is a problem with requesting things 
too fast.  There are various discussions on nxtasy.org such as 
http://forums.nxtasy.org/index.php?showtopic=2940 and 
http://forums.nxtasy.org/index.php?showtopic=4153

Attached is our workaround.  It's not likely the best place or time, but it 
does make things work reliably.  We will try to clean it up.  If anyone 
else has seen this or has suggestions on the best way to deal with this 
please reply here.  

What steps will reproduce the problem?
1.import the IRseekerv2 class
2.using the get_ac_values def
3.run program connected to brick an irseeker

What is the expected output? What do you see instead?
the direction and sensor values. Output is instead nxt.hitechnic.ACData 
instance at a hexadecimal addresses which at the time I dont remeber what it 
was.

What version of nxt-python are you using? On what operating system?
I'm using 2.1.0 on ubuntu version 10.0.4

Please provide any additional information below.

 I am new to PYNXC.

 On directly using the examples program without modification, i get the below error :

NoBackendError("No selected backends are available! Did you install the comm 
modules?")

Should I install something in extra ?

Regards
Praveen

1. Enable several bluetooth devices near the computer
2. try locator.find_bricks() - it will return all of them
3. try locator.find_one_brick() - it will try to get a random device and will 
raise an exception if connection fails (i.e. that random device is not paired).

A simple, but not clean though way to eliminate the problem is to ensure that 
device's name is "NXT". At least the module wouldn't try to connect to 
stranger's laptops.

What steps will reproduce the problem?
1. the mocont web page mentions ways to cancel commands that are being executed 
by motors. This seems to be missing in motcont.py
It is an important functionality to implement: I am happy to do it if you give 
me advice, Marcus.


What is the expected output? What do you see instead?
I expected to see all the functionalities of Motcontrol implemented as from 
their web page.
I was expected to be able to cancel a command, like it is done in :
http://www.mindstorms.rwth-aachen.de/trac/browser/trunk/mfiles/%40NXTMotor/Stop.
m

Basically cancelling a command and stopping, without active breaking.

What version of nxt-python are you using? On what operating system?
Win7x64  nxt-python-2.2.2  bluetooth  python 2.6

Please provide any additional information below.
I am referring to:
http://www.mindstorms.rwth-aachen.de/trac/wiki/MotorControl

"
Cancelling commands

When a certain motor is running, you can always cancel the current operation by 
sending two types of "stop" commands. By "stop" I just mean a certain parameter 
combination for SetOutputState. If you want to stop multiple motors, you have 
to send a direct command to each one of them. The MotorControl program will 
recognize this "cancellation request" and stop the control algorithm.

Reference implementation: @NXTMotor/Stop.m

We've got:

Stopping (coasting)

This means turning off power to a motor, leaving it spinning freely (coasting). 
To do this, the corresping NXC-code looks like this:

SetOutput(port, Power, 0, OutputMode, OUT_MODE_COAST, RegMode, 
OUT_REGMODE_IDLE, RunState, OUT_RUNSTATE_IDLE, UpdateFlags, UF_UPDATE_MODE + 
UF_UPDATE_SPEED);
This is basically just setting a power of 0 and setting everything else to OFF 
or IDLE…

Active braking
[...]
"

What steps will reproduce the problem?
1. run cnc.py on Windows 7 via Bluetooth on NXT latest standard firmware
2.
3.

What is the expected output? What do you see instead?
I expect to see two motors moving at the same time. I see one motor moving and 
an error message as soon as the second motor is supposed to move.

What version of nxt-python are you using? On what operating system?
Win7x64 (but all sw installed as 32bit) Python 2.6Win32  PyBluez_win32_py2_6  
PyScripterWin32

Please provide any additional information below.
*** Remote Interpreter Reinitialized  ***
>>> 
Tick 0
Tick 1
Unhandled exception in thread started by 
Traceback (most recent call last):
  File "<string>", line 532, in write
  File "C:\Program Files (x86)\PyScripter\Lib\rpyc.zip\rpyc\core\protocol.py", line 439, in _async_request
  File "C:\Program Files (x86)\PyScripter\Lib\rpyc.zip\rpyc\core\protocol.py", line 229, in _send_request
  File "C:\Program Files (x86)\PyScripter\Lib\rpyc.zip\rpyc\core\protocol.py", line 244, in _box
  File "C:\Program Files (x86)\PyScripter\Lib\rpyc.zip\rpyc\core\brine.py", line 369, in dumpable
  File "C:\Program Files (x86)\PyScripter\Lib\rpyc.zip\rpyc\core\brine.py", line 369, in <genexpr>
  File "C:\Program Files (x86)\PyScripter\Lib\rpyc.zip\rpyc\core\brine.py", line 369, in dumpable
  File "C:\Program Files (x86)\PyScripter\Lib\rpyc.zip\rpyc\core\brine.py", line 369, in <genexpr>
  File "D:\_DOCUMENTS\_Learning_Python\Nxt20\cnc.py", line 16, in turnmotor
    m.turn(power, degrees)
  File "C:\Python26\Lib\site-packages\nxt\motor.py", line 211, in turn
    raise BlockedException("Blocked!")
nxt.motor.BlockedException: Blocked!
Tick 2
Tick 3
Tick 4
>>> 

is it possible to program the lego nxt robot to move in a square motion forming 
a square based on odometry theory?

Describe the new feature more precisely.

Add a parameter to find_one_brick and find_bricks to disable preliminary error 
output. (Such as USB not available) Of course, keep the catchall that throws an 
official error. Another option would be to have a global nxt module variable 
that specifies if output is requested.


Why do you think it's important?
It would allow automated programs to look more professional and output their 
own error codes.

Any ideas on how to implement it?
Just add a parameter output=True to the functions, and have find_one_brick pass 
to find_bricks. All outputs would then be wrapped with an if block.

Please provide any additional information below.
This is a quick and low priority change that does not change the overall 
function of the program at all.

Describe the new feature more precisely.

Being able to run the nxt-python using python 3.x
Are there any plans on adding support for 3.x?


Why do you think it's important?

I've wanted to write a motion control script for a long time using nxt and 
blender. I just read this post 
(http://www.eibriel.com/2012/05/06/camera-motion-control-controlling-steppers-wi
th-blender-tutorial/) and really inspired I thought I'd check out if I would be 
able to control my nxt from within blender. Blender uses python 3.x so...


Any ideas on how to implement it?

Sadly no, but I haven't done to much research either..

Please provide any additional information below.

Thank you very much for your time and effort on this module!

What steps will reproduce the problem?
1. Connect a NXT brick
2. Move a motor

What is the expected output? What do you see instead?
The motor moves farther than it should, because it coasts after it goes 
the specified distance. Ideally, it should move the specified distance, 
then brake or coast (whichever the user wants it to do).

Please use labels and text to provide additional information.
The way to do this is the same way the NXT-G "IDE" does it:
1. Go specified distance.
2. Immediately go backwards a bit.
3. Check how for off the motor is from where it should be.
4. Correct the difference.
5. Repeat steps 3 and 4 until it is within about 3-5 degrees of perfect.

I'll be working on this. If anyone already has a program that does the 
same thing, say something!

* Describe the new feature more precisely.

As it doesn't seem you are bogged down with issues, I thought I would like to 
address the following issue.

I have created a multiple Thread program, which has threads for the sensors and 
threads to control the motors.  In this way I aim to continually pole the 
sensors and stop the motors when I detect a certain event. However, I get a 
datagram error as I am sending multiple requests to the NXT controller 
simultaneously. Is there currently a way to have the NXT control module handle 
requests in a queue?

* Why do you think it's important?

Would then be able to have multiple threads monitoring sensors and issuing 
commands to the motors

* Any ideas on how to implement it?

Yes, although I usually get slated for my workarounds! :)

* Please provide any additional information below.

My idea would be to create a queue in the control module, and then process each 
request when possible.

The culprit is here (I don't have the sensor so I can't check):

http://code.google.com/p/nxt-python/source/browse/trunk/examples/mindsensors/ACC
L.py#13

I tried a code review for this too.

Cheers.

I thought I'd respond to:

https://code.google.com/p/nxt-python/issues/detail?id=18

As I have such hardware.

First run: http://sprunge.us/FRJI (motor controller first in chain) (set_power 
worked as expected)

Second run: (motor controller second in chain) http://sprunge.us/fjaA 
(set_power worked, but nothing else)

I thought I might mention as of something like 10 days ago, the lejos SVN has 
100% working drivers for these controllers. I don't have an encoder, so I can't 
test that functionality, but aside from that, I'd be happy to work with any 
improvements you might consider making for this.

What steps will reproduce the problem?

1. Install pyusb
2. Install nxt-python
3. run `python spin.py`

What is the expected output? What do you see instead?

    Traceback (most recent call last):
      File "spin.py", line 12, in <module>
        b = nxt.locator.find_one_brick()
      File "/Library/Python/2.7/site-packages/nxt/locator.py", line 112, in find_one_brick
        for s in find_bricks(host, name, silent, method):
      File "/Library/Python/2.7/site-packages/nxt/locator.py", line 43, in find_bricks
        for s in socks:
      File "/Library/Python/2.7/site-packages/nxt/usbsock.py", line 84, in find_bricks
        for bus in usb.busses():
      File "/Library/Python/2.7/site-packages/usb/legacy.py", line 333, in busses
        return (Bus(),)
      File "/Library/Python/2.7/site-packages/usb/legacy.py", line 329, in __init__
        self.devices = [Device(d) for d in core.find(find_all=True)]
      File "/Library/Python/2.7/site-packages/usb/core.py", line 846, in find
        raise ValueError('No backend available')
    ValueError: No backend available

What version of nxt-python are you using? On what operating system?

Mac OS X 10.7.2 with nxt-python 2.2.1

Please provide any additional information below.

NXT is turned on and connected. Same steps work on Linux.

PyFantom does not get detected, LightBlue does not even install. I'm able to 
control the NXT with remote control software.

The three provided scripts (nxt_push, nxt_filter and nxt_push) use the 
unportable shebang line. This cuases problems when people use the script in a 
nonstatndered environment, such as running scripts from inside "~/bin" in 
restricted enviroments.

Implementing the fix below should unaffect any modern system but provide extra 
portability.

change #!/usr/bin/python
to     #!/usr/bin/env python

the method read_values is missing from the Accelerometer class. 

 File "/usr/local/lib/python2.6/dist-packages/nxt/sensor/hitechnic.py", line 73, in get_acceleration
    xh, yh, zh, xl, yl, zl = self.read_values('all_data')
AttributeError: 'Accelerometer' object has no attribute 'read_values'

What steps will reproduce the problem?
1.Install Python 2.7.2
2.Install PyUSB 1.0.0a2 to python 2.7.2 directory
3.Run installer for nxt-python 2.2.1

What is the expected output? What do you see instead?
Expected successful installation of nxt-python. Instead console produced the 
following:

Traceback (most recent call last):
  File "P:\Pythin27\lib\site.py", line 563, in <module>
    main()
  File "P:\Pythin27\lib\site.py", line 552, in main
    aliasmbcs()
  File "P:\Pythin27\lib\locale.py", line 15, in <module>
  File "P:\Pythin27\lib\encodings\)__init__.py", line 32, in <module>
    from encodings import aliases
ValueError: bad marshal data (unknown type code)
-=-=-=-=-=-=-=-=-=-=-
There was an error during the installation.
Please check the above text for more information.
Press any key to continue...

What version of nxt-python are you using? On what operating system?
Version 2.2.1 on Windows XP

Please provide any additional information below.