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motors wont run 
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Joined: Sat Oct 25, 2008 12:18 am
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Post motors wont run
RobotC, compiles and loads simple program to run motors A and B for 3 sec. Debugger says it is running, as does the NxT brick, but motors won't turn. There's 12V to motor controller, and when we take the motor controller out of the circuit and go directly from NxT brick to LEGO motor, it runs fine - can control speed and direction. Have taken unit home to put scope on motor controller, but ?? Anyone else have this problem and solve it? Thanks, Chuck


Sat Oct 25, 2008 12:24 am
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Joined: Fri Feb 09, 2007 9:21 am
Posts: 615
Post Re: motors wont run
IS the 12V battery fully charged? ROBOTC will turn motors off if voltage is below 10V. [And Make sure you've downloaded the latest ROBOTC version -- because the CD version had a higher cut-off limit that was appropriate for the 14.4V motor used for the field trial and not the 12V battery that shipped with the competition kits]. You also want the latest version because it has a work around for controlling "braking" motors.

Here's a quick way to test if the motors and motor controllers are working properly. Check the top line status display of the NXT. if the top right shows a single battery icon then it's misconfigured. When properly configured you should see two battery icons; one if for the internal battery and one is for the external 12V battery.

To configure you need to use the "Motors and Sensors Setup" command on the "Robot" menu in ROBOTC's IDE. And then once you've configured it, you have to run your program to make the configuration known to the firmware.

And, are your using the right motor ports?
  • Motor A, B, and C are the three built-in motor ports on the NXT.
  • Motor D and E are the two motors on the HiTechnic Motor Controller. The normal configuration is to plug these into Sensor Port '1' but you can change this with the "Motors and Sensors Setup"

You might find watching the pre-recorded "Webinar" on ROBOTC on the CMU web site.


Sat Oct 25, 2008 1:14 am
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Post Re: motors wont run
Bat at 13.x V - at the motor controller terminals (switch is on :o)). Using and config to port A, but have also tried B, C. Again, if we plug the NxT motors directly into port A, B, C (whichever we have spec'd in software), the motor will run, if we then plug that cable into the motor controller, with 13.x V on the terminals, and run the program, the big motors don't even twitch.

We had some trouble getting the NxT driver onto our computer, but sure looks like it is communicating - debuggers work - NxT display and motor monitor seem to work at least with the NxT motors. Gave servos a go through the servo controller, but didn't get that to work either - need to spend more time there today.

We've watched the Webinar 1, AND done quite a bit of work with VEX over the last 2 years, and have been successful this year using RobotC. We uninstalled the Vex version and downloaded and installed the newest version of RobotC from ftctraining.com - vs 1.46, I think. And then downloaded the latest firmware to the NxT.

Have been through motor configuration (and downloaded changes to NxT) several times. Initially used PID, since we'd hooked up encoders, but have unplugged encoders and unchecked PID, to no avail.

Will go back to Webinar, check bat icon and start with 1 motor and new program today, but I am suspecting the motor controller isn't working right. Shouldn't we be able to see some DC voltage and catch the PWM outputs on the motor ports of the motor controller?? Would be good to have LED indicator on that H bridge, like the Victors on the FRC robots. That black box staring back at us isn't very comforting or of use for diagnosis.

Thanks.

Thanks for help.


Sat Oct 25, 2008 8:03 am
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Post Re: motors wont run
Try following the attached directions. Sorry, it is from a file with picture that I cannotupload to the forum-- it won't take a 400K file! So it's a little hard to follow without the images.



Testing 12V Motor Performance
1. Open the “FTC Controllers” debugger window as follows.
1. Set ROBOTC to “Expert’ user level
2. Open the “Internal” tab on the “Preferences and set the check mark for “Enable Super User”
3. Set to “Super User” level. This adds more menu commands and windows.
4. It is easiest to work with a USB connection, but this should also work over BT.
5. Open the debugger and run a program that has HiTechnic controllers equipped via the “Motor and Sensors Setup”. This will get the HiTechnic controllers defined in the NXT.
6. Power cycle the NXT. This step shouldn’t be required but I’ve added this just in case. This is done once only and will cause the NXT to store the Controller configuration into flash memory. Re-open the debugger.
7. Open the debugger Window “FTC Controllers”. This displays a window with one row of info for each HiTechnic controller.
8. Make sure the debugger is in “Continuous” polling mode.

2. Verify the Motor Controller is Working Correctly

Verify the following:
1. Battery level should be at least 11 volts.
2. Resets for each controller should be a very small number. This is a count of the number of soft resets performed on the controller. A soft reset is performed whenever the controller has an I2C messaging failure.
3. The “Cycles” field for the motor should be increasing at a very fast rate.
4. Turn off the 12V power. The Motor Controller “Reset” counter should be dramatically increasing and the “Cycles” count should not. The Servo controller will still have “Cycles” incrementing because there is only I2C traffic when a servo changes position and nothing has been changed.
5. Turn on the 12V power. Should be back to “normal” with the “Cycles” field for the motor increasing.
6. NOTE: the above two tests have just confirmed that it doesn’t matter whether the 12V is powered on before or after the NXT!

7. Disconnect the sensor port cable. Should give you the same impact as turning off 12V battery; i.e. “Resets” increasing, “Cycles” frozen.
8. Reconnect the sensor port cable.

9. If connected via USB you can safely turn off the NXT without screwing up the ROBOTC IDE. You should get a message that USB link has failed.
10. Now turn on the NXT again.
11. Now click on the “Continuous” button on the Debugger window. This will restart the polling via USB. You should see that all the above counts are behaving nicely.
12. You’ve just verified that ROBOTC has nicely saved the HiTechnic Controller configuration in a flash file (Config.sys) and has nicely restored it on power up.

3. Verify correct operation of motors.
1. From the above configuration with the debugger open, open the windows for both “FTC Controller” and for “NXT Devices”. Click on “More” for the NXT devices. You’ll have a display like the following.



2. Set “MotorD” to the following parameters.




3. Verify that that motor encoder counts are incrementing / decrementing and in the correct direction. It’s possible that the power leads to the motor and the encoders are opposite. If the wrong direction, then swap the motor leads.
4. Experiment with various power levels. The motor should noticeably move faster and slower. And in reverse. You might find at the low speeds 5 or 10 the motor is not moving at all.
5. Now click the “Reg” (Regulated speed) check mark in the bottom half and repeat the above step. You’ll find more uniform speed control. And some inconsistentcies like trying to switch speed from 100 to 5 will cause the motor to briefly go in reverse.
NOTE: the speed regualation code is implemented within the Motor Controller.
6. Repeat above with “motorE” to verify it is wired correctly and working OK.
7. If above has passed, then 12V motors, HiTechnic Motor Controller and ROBOTC firmware are all operating coreectly.


Sat Oct 25, 2008 10:24 am
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Joined: Fri Sep 19, 2008 1:22 am
Posts: 200
Post Re: motors wont run
chuckmerja wrote:
Using and config to port A, but have also tried B, C. Again, if we plug the NxT motors directly into port A, B, C (whichever we have spec'd in software), the motor will run, if we then plug that cable into the motor controller, with 13.x V on the terminals, and run the program, the big motors don't even twitch.


Please post your code (including the #pragmas at the top). The NXT ports A, B and C are for NXT motors only. Likewise the variables motorA, motorB and motorC only refer to the NXT motors. The default names of the two 12V motor ports on the first controller on port S1 are motorD and motorE.

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Benson Robotics Club


Sat Oct 25, 2008 10:41 am
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Joined: Sat Oct 25, 2008 12:18 am
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Post Re: motors wont run
Grrrr - GOT IT! We'd grabbed a "test motors" program NOT from FTC, but from some other (NxT) "sample programs" subdirectory - probably why it worked with NxT motors on ports A, B :o)). Once we read your comments and found an FTC Test Motors program, we were in business. THANKS Jeff and Dick!! Now on to joysticks.


Sat Oct 25, 2008 1:33 pm
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Joined: Mon Jun 01, 2009 1:05 pm
Posts: 1
Post Re: motors wont run
actually the ROBOTC, compiles and loads simple program to run motors A and B for 3 sec. Debugger says it is running, as does the NxT brick, but motors won't turn. There's 12V to motor controller, and when we take the motor controller out of the circuit and go directly from NxT brick to LEGO motor, it runs fine - can control speed and direction. Have taken unit home to put scope on motor controller, but ?? Anyone else have this problem and solve it? Thanks, Chuck i learn so many today,,,things for the tips,,,




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Mon Jun 01, 2009 1:16 pm
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