Asked — Edited

ARC And Third Party Servos

I tested ARC with hitec servos, and discovered ARC is not able to make them move in their full rotation range, largely exceeding 180.
The full ARC 0-180 range produces a rotation of about 163. And , of course, no corrispondence between the degrees set and the actual servo position. I was told by DJ Sures, that ARC was made for ezb servos, and compatibility is not guaranteed with hitec servos. I should suggest EZ to make a software update to ARC to let users configure it to their own servos. I think it shouldn't be a difficult task. It woulde be useful to many users !


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#1  

In my humble opinion is not an ARC issue (a new software configuration option) it's a Firmware issue.

The EZB controller has 2 micro-controllers, one is used for the WIFI and the other one manages the hardware ports & speaker.

Both micro-controllers do not support over the air updates, the only solution is to use 3 party tools.

Unless there is an EZR firmware builtin functionality (not advertised until now) to specify the min and/or max servo pulses, i don't see that happening.

currently we are able to flash the WIFI micro-controller :), nothing is impossible but is not so simple.

Let's wait for DJ's answer.

#2  

You're right, the limitation must be in the firmware. We can only ask EZ and wait for a future ezbv5 !.... DJ made me see an oscilloscope skecth, showing the pulse range of ezbv3, that was wider than ezbv4 I have. They changed, mantaining compatibility with EZ servos, but not with hitec's.

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Synthiam
#3  

Unfortunately there will not be changed to ARC to support third party hitec servos. If you wish to use incompatible third party servos, consider adding an arduino or ssc-32 to the ezb as a secondary controller.

#4  

@leonardo46 You could try using a servo stretcher like this: https://www.servocity.com/html/180o_servo_stretcher.html

But it will effectively add $20 to the cost of each servo.

#5  

Yes, the servo stretcher from Servocity is your best bet for Hitec servos.

#6  

I burned up 2 ezrobot mini servos using the ssc-32 by sending 2500us pulse (maximum) to those servos... These servos were possibly pinned against their stops which would of course cause them to burn... After that I restricted my mins to ~600us and max to ~2400us just to be sure to protect from future burned servos....

I have no idea how @DJ set his servo mins and max for ARC and/or firmware, but if it were me doing this I would hard code for a buffer at each extreme to help protect servos from accidently hitting their stops...

#7  

Richard, there are, in ezb script, statements to prevent servos reaching their stops. Yes, I might use servo stretchers or other controllers. EZB has greatly reduced my hardware .It does everything ! Unfortunately I'll have to increase my hardware again.

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Synthiam
#8  

I'm sorry to hear that you have to increase hardware again. however, the ezb firmware is hard coded for the servo max/min positions and cannot be altered. While this may not provide full servo range with your application, it assists tens of thousands of other users by providing pre-calibrated ezrobot servos for their revolution robots, specially in schools and educational facilities.

Adding the ssc-32 is only 2 wires - and will free up many digital ports on the ezb for other features... Such as leds or switches , etc