Asked — Edited

Slider Question At 45%

I hooked up two motors through a H bridge and everything seemed ok at first. I noticed that as I moved the slider up and down it had a shift in the speed on each motor. It appears that when the slider is at 45%, the ez-b output goes to 5 Volts. I thought maybe it's a problem with my motors or H bridge, so I put a meter on another digital port. It was the same thing, 5 volts at 45%. Any ideas? Thanks


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Are you referring to the PWM Slider?

Disconnect the motor controller and use the slider with a meter and check again - it should be about 2.3 volts.

Also, check if any other controls are using that port and setting it to ON.


Yes I mean the PWM slider. I have two for the motor shield ,one for each motor and one for a port with just a multimeter and another that I use for leds on three different ports that have leds on them . They are all the same the output tracks the slider position up to 44% then at 45% the output goes to max (5 volts), then at 46% the output resumes tracking the slider position up to 100%.It's like there is a wrong value is assignend to 45%. Thanks for your responce.


Disconnect the motor controller and use the slider with a meter and check again - it should be about 2.3 volts. Maybe the connected device is raising the voltage.

Also, check if any other controls are using that port and setting it to ON.


DJ, I did as you asked, but I still see the problem. I've had my ez-b for a while and have not had any issues what so ever at all until this This is also the first time using the PWM slider too. I removed everything from the board, rebooted my computer, cycled the power to the board and then connected a meter to each (all twenty) digital port. Using a new program with only a PWM slider at each digital port and at 45% it goes right to 5 volts. Really strange, the good news is this is not stopping me from moving forward on my project.:) Thanks, John


Anybody else have any ideas on what this could be?


Do you actually see the motor jump to 100% speed when the slider hits 45?

As I understand what your saying; with the motor connected when you reach the 45 mark on the slider the motor will jump to 100% speed. Then when you slide it past 45 and continue up the motor wil drop down in speed to where it should be and then continue properly up to 100% as you push the slider up to the top?

Have you tried a different motor controller? What type are you useing?


Yes you have got it right. The motor driver that I was using was a Seeed Studio motor shield. I stopped using it and went back to my Sabertooth. The problem is observable with a voltmeter or a led on any of the 20 i/o ports.


Odd, if the problem is there with both motor controllers then that would appear to rule out them. Do you have a different computer you could try with a different bluetooth and a fresh install of ARC and new project? If the problem is still there useing the new set up you can say it's either the bluetooth unit on the EZB Board or the board it's self.


Ok, I have tried three different computers and three different versions of software, the problem is still there. The board has performed flawlessly except for this PWM Slider. It does it on all of the digital ports and can be observed with a meter or a motor or a Led. I think its software:) Maybe someone else could check their board? Thanks

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Yes, I tried this a few weeks ago and noticed at 45 on the slider the PWM is at 100% on the board. I haven't tried since the updates of late though, I had assumed it was fixed but possibly not if you still get it.

I was using it on the 2.5A H-Bridge.

When I get chance I'll knock up a quick ADC/PWM test circuit & script. I did just try it by jumpering the Signal of D0 to the signal of ADC0 but I got strange results, I guess it needs a resistor (which I recall reading somewhere else anyway but haven't the time to do it properly right now) or can't be measured like this... Either way I will do some further testing.


Thanks for the verification Rich. Also , I should get this out there too, with the PWM Slider, when I go from a low setting of approximatly 15 to 30% and press the Stop button, the output goes to full on. As you can imagine, this is not desirable.


I decided to leave the PWM slider alone and move on. Now in my script when I set the pwm value to 0 it goes high. To get the motor to stop I have to send a value of 1. Also under script control 45% puts out 5 volts. I guess I could write into the script that if the pwm output is ever 45% to set it at 46 or 44% instead. Any ideas on what to do? Thanks

United Kingdom

I haven't had chance to check this out since my last post but I'd agree that there is an issue with PWM at 45%. DJ will add it to the list and look in to it. Hopefully it isn't an isolated problem and he can replicate the behaviour but if that is the case I am sure he will work closely with us to resolve it.

Until then, you can use a work around to skip 45%

IF ($pwmvalue = 45)
  $pwmvalue = 46

Where $pwmvalue is the variable you use for the speed/PWM.


Thanks Rich ! Ill use that for now and I will try using Set digital output at 0 for the off value.