kirkpthompson wrote:I wonder if your unit got buggered up somehow with the low voltage and ([relatively] high current draw(?) of the motors). Have you asked Mindsensors tech support what the behavior your unit is experiencing may be?
I am not excluding the possibility of the MMX classes being buggy. Can you provide the error messages that are appearing on the LCD?
Can you write a simple test case (or use the NXTMMXSample in \Samples) that sets up the motors and turns them on (no threads, control schemes etc.) for a period of time to see if the unit itself is working without glitch in a very code-minimal usage scenario?
I'm going to try and test it with normal NXT motors...
kirkpthompson wrote:I'm going to try and test it with normal NXT motors...
What type of motors are you currently using? I tried to use the NXTMMX to drive a Firgelli linear actuator but they would only respond when the power/speed was set to high level. If you are using non-LEGO NXT motors, and you ramp speed up/down depending on position of your tilt sensor, maybe they have the same problem and they are only responding when the output of the NXTMMX reaches a certain level and then the motors suddenly "lurch" on (at that high output level). That could explain the "hickuping".
I suspect that the NXTMMX PWM output does not match what the LeJOS firmware provides but am not competent with a scope (and don't have one!) so I can not validate this theory. I queried Mindsensors back in May on this and never did get a reply.
What did you open up? Which Motors are inside? Can you post pictures, product names, or anything else that would give us an idea what you're talking about?Rickz2020 wrote:I have no idea what the specs are for the motors. I've opened it up and they are just those cheap "squarish" motors with grey housing; You know, the ones in most kid toys.
Rickz2020 wrote:At least this is progress
skoehler wrote:What did you open up? Which Motors are inside? Can you post pictures, product names, or anything else that would give us an idea what you're talking about?
skoehler wrote:If you don't know anything about the motors, how do you know that they actually provide the feedback (tacho count), that is required for successfull speed regulation? I guess, the motors don't provide that, which means they will not work with speed regulation. Not sure, whether the speed regulation of the NXTMMX can be turned off.
I held the motor in place(preventing it from rotating) and applied power. Then, I connected the multi-meter across the motor terminals and watched to see what happened. I've noticed that the power seems to get "interrupted" when the motor is prevented from rotating
Is this what you guys are talking about regarding not receiving feedback from a tacho?
Does this mean I need to get specific motors?
kirkpthompson wrote:Philo has a good page on NXT motor guts: http://www.philohome.com/nxtmotor/nxtmotor.htm
...edit the leJOS code, flash my NXT brick, re-install leJOS on my NXT and then see if it solves the problem. What do you think?
I guess the NXT motors are designed to rotate to a spot and lock if needed by calling .lock(); rather than have them physically stopped by an outside source.
The problem is that in London there are not many hobby stores and very VERY few places that sell lego components
kirkpthompson wrote:...edit the leJOS code, flash my NXT brick, re-install leJOS on my NXT and then see if it solves the problem. What do you think?
Well, I don't code at that level (gcc, make, toolchains, etc.) so I can't really answer that question but I don't readily see where you are going with this since the NXTMMX is its own unit and only communicates with the NXT via I2C (as a sensor basically) so I don't really understand why you need to change the NXT firmware. gloomyandy has a lot of experience with the firmware and may be the best to try to understand what you want in that regard if you can communicate your need succinctly.
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