View Full Version : Problems with Arbotix Pro connecting to servos

10-06-2015, 05:24 PM
I'm a TA in a robotic class and we have 15 HR-OS1 robots, and we kinda have the same problem with Arbotix Pro over and over. So those are my observations about what's going on:

1- After working with rme for over than 3 hours 2 or 3 teams had the same problem where the robot's legs turns towards each other and jam after sending "Play" command from rme, and after restarting the robots, it fails to identify any servo, and after checking with robo plus and DXLMonito, it appears that the subcontroller works fine except it doesn't communicate with the servos anymore. Other teams just had the problem with rme but they used it for less time than others.

2- Another board had a different problem, it was working fine but the ARM chip overheats immediately after power up, so we just took it out and replace the board.

3- I checked one of them using the instrunctions in this thread: http://forums.trossenrobotics.com/showthread.php?7542-Arbotix-Pro-doesn-t-recognize-servos&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+TRCommunity+%28Trossen+Roboti cs+Community%29
I tried using the oscilloscope and connected the probes with TX and RX pins and watched them when I powered up the board and after connecting the servo and after connecting the micro usb to the computer and there was no change even after I switched the Dynamxle Power to "On' from robo+. There was one thing though when I checked the 5V pin and 3.3 V, they both gave me 2.2 V on the Oscilloscope(I didn't have odometer at the time) for some reason.

We've already sent back 4 boards but we have two more broken ones today, so we will send them back soon. But I need to know if we should avoid or do something to avoid this problem in the future.


10-06-2015, 05:58 PM
I am curious on which processor are you using? i.e. Edison or RPI2?

Again this may be completely different, but I have (or had) issues with RPI2 and likewise Odroid C1+ communicating with Arbotix Pro as I talk about in the thread: http://forums.trossenrobotics.com/showthread.php?7617-Trying-to-debug-HROS1-with-RPI-talking-to-Arbotix-Pro

I am having some better luck now when I made a mod to the framework that makes sure a write out to the USB associated with the Arbotix-pro is completed, before it sets the timeout for waiting for the reception of the response. This appeared to eliminate most (maybe all) of the error messages I was seeing where for example dxl_monitor or ps3_demo would say it could not communicate or for exampe if you did a scan in dxl_monitor and sometimes it would fail to talk to retrieve the status of some of the servos.

I put in a pull request to the main HROS1-Framework (https://github.com/Interbotix/HROS1-Framework/pull/13), which so far has not been integrated nor any comments. You might give it a try to see if it helps.