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Thread: arbotix-M scorpion X newbie

  1. arbotix-M scorpion X newbie

    I've been perusing the forums as best i can , so apologies if the answer has eluded me .....

    So, just received my Scorpionx today. Trying to get up and running on Win10 with arduino 1.8.5. (mistake #1 ?) .... but before I ask about that ....
    I run Dynamanager on one of the MX64 and it moves to positions for about 5-8 secs and then loses contact. i reconnect and same thing.

    I'm trying to figure if i should wrestle with this arbotix-m at all ..... is it a Java issue ?(too new?) is it a win 10 issue ?(too 'new'?) is it the default ROS sketch on board the controller ? Are all of these modern environments just not going to work with this old code ? Have I bought yet another increasingly aged brick/controller ?

    What are kids learning/doing in 'robot school ?' Dynamixels ? What controller ?

    Dynamixels are so full of promise, but what is the best controller scenario ? Seems like the controllers and their code are always 'playing catch-up' but never quite there. And then everything changes. Maybe it's just me
    Should I go back to the OpenCM 9.0.4 and wrestle with that instead ?

    summation:just like to know a way to control position of a couple of mx64 from my win10 pc laptop(python or serial) and retain what's left of my hair

  2. #2

    Re: arbotix-M scorpion X newbie

    Sorry, I am not much of a python person... Also don't have any MX servos, only AX... Although I do have 2 new XL430-W250-T shipped to me, so I can start learning these new servos and Protocol 2...

    As for best controller. Always a hard thing to answer as everyone has different ideas of best...

    Simplest thing to use on a PC, assuming you want to do all of the control of the servos on your PC: Probably the USB2AX - http://www.trossenrobotics.com/usb2ax But it is simply a servo controller and mainly only forwards messages it receives on the USB to the servos on the AX/MX buss, but it is limited to TTL versions of servos.

    The Arbotix-m: is a pretty simple 8 bit, 16mhz 64K/4K memory, AVR processor, with slightly more resources than an UNO (more memory, 2nd Usart) and less than an Arduino Mega... But it is often sufficient to get simple things done. Note: other than from a few of us up on the forums, there is very little support for these boards. Their official Arduino release is still back at Arduino 1.0.? release. There are a few of us who have versions setup for the more recent Arduino releases.

    OpenCM 9.04: I have recently started playing with them. They are cheap - Arm M3 72mhz, 128/20 memory... One issue with the current C version is there are no AX/MX servo connectors. Can fix a few different ways: Buy the A version and solder in the appropriate connectors, unsolder some on C and solder in new ones, Use their OpenCM 485 expansion board, which has connectors for TTL as well as 485 servos. Or simply setup a conversion cable and jumper it over to an AX/MX powered HUB...

    Personally I like using my own boards that have on them Teensy 3.x modules on them from PJRC.

    So again what is best? Good question!

    I am not sure if it means much, but as I mentioned I have two new X servos coming (Friday) and I plan to first try them out on the OpenCM 9.04 boards and then, migrate support for them over to my Teensy 3.x code base. I am in the process of migrating my code for the PhantomX (Phoenix code base) over to the Robotis Dynamixel SDK and away from the older Bioloid libraries....

  3. Re: arbotix-M scorpion X newbie

    Thank Kurt,
    sorry if I jumped in a bit frustrated. You've provided some good breadcrumbs.
    I have actually dabbled in openCM 9.04A prgramming. I have a prot 1 an a prot 2 motor. I switched to arbotixM because I was trying to find a way to 'easily' integrate a pair of xbee transcievers i had and make wireless serial control a possibility. the Arbotix M xbee slot for this looked appealing. Now I'm vacillating on going back to openCM, despite their lack of support for xbee. I actually had xbee and 9.0.4 working on a second serial port in Open CM, but got frustrated with attempts to make a reliable protocol.Then i used the SDK to use the work done by Robotis to implement Python control, running a python applet that my host was feeding variables over UDP (long story). etc. etc.

    'All' I really want to do is send position to 2-3 dynamixels,return position to my host app( in 'real time'). My host app is Python based. I was able to use a 9.04 'tosser' program to toss over a packet from my host, but had trouble with CRC check sum forming. its pretty easy with protocol 1 , but more involved with prot 2 checksum. i just got this Scorpion X thinking I would be able to control realtime position remotely from my PC relatively easy. I got the arbotixM to go to position using :

    ax12SetRegister2(1,30,TravelX);

    now today I'm working on forming an efficient serial command to send from my host, and how to best (close to real time as possible) read arduino buffer for this...... there might be 'life' in this arbotixM after all ! thks for the interest i will keep informing my progress.
    today i havent quite given up on the little arbotixM.

  4. Re: arbotix-M scorpion X newbie

    "Personally I like using my own boards that have on them Teensy 3.x modules on them from PJRC."

    Hi again - so if u are using Teensy - what is the physical interface between teensy and dynamixel ?

  5. Re: arbotix-M scorpion X newbie

    So I got the arbotix to receive a long int as ASCII over serial, and it seems pretty snappy. Now I am looking for code to receive multiple long ints on arduino side. ive perused many examples, but not found exactly what im looking for. but the good news is it seems like ASCII strings over serial will work for my basic communication protocol. Part of the secret seems to be adding a delimiting null char at end of message.

  6. #6

    Re: arbotix-M scorpion X newbie

    Quote Originally Posted by cod65 View Post
    "Personally I like using my own boards that have on them Teensy 3.x modules on them from PJRC."

    Hi again - so if u are using Teensy - what is the physical interface between teensy and dynamixel ?
    Depends. If I feel comfortable with driving the servos with 3.3v logic output from the Teensy, I connect up one of the Usarts TX pin to the TTL pin for the bioloid servos plus GND. The first few times I did it, I hacked up a bioloid extension cable and discarded the power pin, and connected up the other two as I mentioned. The other side of the cable I plugged into a powered AX/MX HUB that Trossen sells...

    This works with my BioloidSerial library, where I have it setup, that when built on a Teensy it will enable the USART into full duplex mode (uses TX pin for both RX and TX) and the code will switch the pin from RX/TX at the appropriate times...
    I never had signal issues I could attribute to 3.3v signal.

    However to be more in SPEC, some of the boards I played around with I added level shifting (buffer), that converted the 3.3v signal to 5V signals. I have done this two ways. One way is to do like the above and use a single bidirectional shifter... The other way is I hooked up one or two chips that did the level shifting. The chips I used were setup to work like an RS485 converter with another pin as a direction pin. With this there is support in the Teensyduino code to enable an RS485 level shifter to the serial port and the underlying code takes care of setting the direction at the right times. Again support for this is in my library.

    Nte: So far I have only worked with AX servos Protocol 1, as I mentioned I do have a couple of servos that talk Protocol 2 that were supposed to arrive today, but UPS delay until Monday... Will update code to work with these.

    As for XBees with OpenCM9.04... I have one hooked up to my PhantomX with OpenCM9.04 right now... I did a quick and dirty Layout for an XBee with the same connector on it that OpenCM for the modem...

    Name:  de5b6f879f053cccd25295bfb4793068.png
Views: 36
Size:  27.3 KB

    I think this was the earlier version which I am actually using. I made a minor updated version of it that put the mounting holes on 1cm grid so can attach to top of Hex... I have not setup which exact parts to use.... Takes two of the 2mm XBee like connecctors, probably ordered last batch from Sparkfun or Adafruit. The connector I used I got from a quick and dirty order from Amazon, which had several connectors and wires: https://smile.amazon.com/gp/product/B01DUC1S7S/

    I could have spliced two of those wires together but wanted a wire. The ones I ordered are not fully correct:
    https://smile.amazon.com/gp/product/B01CNZ9RJO/

    But was able to make work, by trimming some of the edges off the connectors...

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