ActivityBot Encoders

jrhanobik

Been away from this for a bit, but yesterday, I had time to start back up. Went through the navigation tutorials for the ActivityBot just to brush up and all was fine. Encoders hooked up properly, tested out correctly. Bot tracked straight and reasonable results with the turning tutorials. Doing this as I try to integrate with ROS. Noticed that I was a bit behind in the SimpleIDE and support files, so downloaded the new one. Now, encoders do not work at all. They seem to be pulled high constantly. Called support and they said that they had not heard of similar and to throw it out to the forums. Has anyone else experienced anything like this after upgrading the ide and support files? Is it possible to get the old one anywhere just to try?

Thanks,
-john

Andy Lindsay (Parallax)

About the always pulled high part, did you use this to check?

http://learn.parallax.com/activitybot/test-encoder-connections

If you ran that code and the encoders really are pulled high, start by double-checking everything on this page:

http://learn.parallax.com/activitybot/electrical-connections

If that doesn't fix it and you have an ActivityBot that was purchased more than a year ago, search for "You may need to adjust the servo or servo bracket." on this page:

http://learn.parallax.com/activitybot/troubleshooting

On the other hand, if the encoders tested out okay, but the ActivityBot is still misbehaving, it is possible that the library is old enough that it's looking to a different set of EEPROM addresses for calibration data. To test for that, run the program with the drive_displayInterpolation() call on this page:

http://learn.parallax.com/activitybot/calibrate-your-activitybot

Here is an example of a healthy interpolation table data set: http://forums.parallax.com/showthread.php/154622-Activitybot-questions?p=1250425&viewfull=1#post1250425. The values for left and right servo should start with 1000. Then, they should maintain some average value in the 170 to 200 range for around 15 rows. Then, the values should decrease to zero, and increase back to 170 to 200, and end with another 1000 value.

If that IS the way your calibration table looks, then it's fine. If NOT, re-run ActivityBot Calibrate. (Same page http://learn.parallax.com/activitybot/calibrate-your-activitybot)

jrhanobik

Yep, did all of the steps you provided. This particular ActivitBot and encoders all worked fine yesterday prior to updating the IDE and support software. Absolutely no other changes. After the update and doing the tutorial that uses pins 14 and 15 to drive the 2 LED's keeps them high.

Andy Lindsay (Parallax)

I have not been able to repeat your symptoms with a software or learn folder update.

One thing to check. Do the P12/P13 and P14/P15 power shunt jumpers have little handles on them? If so, they may be loose enough to fail to maintain the electrical connection. I have seen a 1 day to the next symptom with these, especially with the encoders, (P14/15). I would recommend taking that jumper off, and bending the pins it shunts ever so slightly away from each other so that when you put it back on, it maintains firm electrical contact.

Andy

jrhanobik

So I methodically tested each of the pin set, 12/13, 14/15, 16/17 with a simple app to basically run a servo just to see if I happened to kill the encoder pins somehow. All worked but I started to notice that the servos were a little twitchy despite having, what I thought were fully charged batteries. I also noticed that when I loaded the programs to the various pins and pulled the usb connection so the bot could run freely, all servos stopped. This led me to believe that the board was getting less than full power from the lipo battery pack. I substituted a standard 5 cell battery pack and all was fine certainly pointing a finger at the rechargeable batteries. Pulled the lipos and checked one by one. Appears that one of the cell, that was just functioning perfectly fine before, is now completely dead thus I was only getting 3.7 v to the board. This explains why the encoders never appeared to have gone high. I apologize for the situation as based on the changes I made, updating only the software, I never would have suspected a cell going dead. Long tedious lesson, but learned a lot in the process. Thanks for all your help, suggestions and feedback.