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Australia
Asked — Edited
Resolved Resolved by Dunning-Kruger!

Sabertooth 2X5 + Ez-B 4 Setup + Battery Considerations

Hi all,

I've been playing around with my Ez-B 4 controller and loving every minute learning about its features.

The robot I intend to install it into is a Lynxmotion Johnny 5 tracked robot, with minor modifications (the original SSC-32 servo controller has been removed). I've become really confused on how to set up the Sabertooth 2x5 R/C motor controller however on the EZ-B.

The Sabertooth is the R/C model with three separate servo wires for FWD CH1/FLIP/TURN CH2, set to independent control, connected to a 3800mAh 11.1V Lipo battery. As per the SSC-32 setup, I have disabled the battery elimination circuit (BEC) by removing the centre red pin of the CH1 and CH2 channel (scrolll down 3/4 of the install guide below for this):

http://www.lynxmotion.com/images/html/build158.htm

The Ez-B 4 is connected to a 7.4V Lipo battery

The problem ...

- When I plug in the 2x5 CH1 and CH2 servo wires into the EZ-B controller, it powers up the EZ-B! I thought I'd disabled the BEC, and am concerned about 11.1V frying my servos (Hitec 645-MG)

- Can I run the 2x5 off the 11.1V Lipo, and the EZ-B off the 7.4V Lipo (to run the ~ 14 or so 645-MG servos)? The reason I want the 2x5 running off 11.1V is for faster motor speeds (this robot will be used in gait analysis, tracking people's movements).

- Is there another controller that will make things easier - noting I've potentially the wrong Sabertooth (R/C model)?

Thanks in advance - I know I've missed something simple, hopefully ...

Jordi

#1  
I have had trouble using more than 6Volts to power Hitec servos, they didn't seem to like more than 6V. The ez robot servos can use 7.4V no problem, however

Yes, you can use up to 18v to run the sabertooth...

I use Hitec servos in my projects... When I do, I use a 4500mAh Sub C 6V battery to power my ezb and servos... This way I don't need to worry about over volting the hitecs... In the past I have used 7.4v to power my 645mg hitecs but I started getting serious chattering and positioning problems so I went back to 6v max....

The RC version of the sabertooth may not work (I have not modified my RC version to test it, however... so it may still work)... You might be better off with the micro controller version... In my opinion the sabertooth is the just about the best controller around... So with the correct version you only need two wires from the 2 x 5 sabertooth to the ezb... One is ground and the other is to s1 on the sabertooth... Use any of the ezbs digital ports... ground goes to black pin on the ezb and s1 goes to the white pin on the ezb. Nothing gets connected to the red pin...

If you don't want to purchase another sabertooth then you can use a much cheaper H-bridge.... but hooking it up is more of a challenge....

If you still want to use the sabertooth, however...Set the sabertooth in serial mode, a few serial commands an bobs your uncle...

Code:


SendSerial(D0,38400,127) #full forward motor 1
SendSerial(D0,38400,255) #full forward motor 2

sleep(3000)
SendSerial(D0,38400,0) #full stop both motors

Australia
#3  
Thanks Richard, I'll check this info out tomorrow. Obviously I'm pretty new to robotics, my primary reason for purchasing the Ez-B was to simplify the setup of the machine (it was getting too complex too fast, and I needed to scale it back a bit!), so I might look into the non-RC Sabertooth controller should that make things easier.

From online reports it appeared there were varying reports running Hitec servos at 7.4V - but I do have a NiMH 6V 3700mAh battery ready to use. The only reason I stopped using it was the low battery warnings from the Ez-B.

Thanks

JB
#4  
You can shut up:D the low battery warning in the settings of the connection control ... If you stick with it, you'll get over the learning curve quite quickly and really get to enjoy the EZB... Take it one step at a time and check out the learn section here... There are tons of example too... and when or if you get stuck, you can always ask here...
#5  
I'm a littll fuzzy on how your connecting the control side of the Sabertooth to the EZB. I also have not been able to look at the RC version of this Sabertooth from where I am now so if I'm wrong please forgive. However if it's the same as the standard version Sabertooth the 5v pin on the control side of the sabertooth is Output only. If you connect this pin to the 5v digital port of the EZB you will backfeed the little guy. Sabertooth could then power EZB up as you mentioned or even burn it up. Look this over carefully. You dont connect this pin to the EZB. *eek*
Australia
#6  
Hi all,

Sorry for not updating - I had connected the Sabertooth R/C board to the servo ports ... which sounds like a bad thing to do, I have purchased a vanilla Sabertooth 2x5 and will try this out now.

Thanks all for your advice - no doubt more to come:)

JB
Australia
#7  
Hi again,

I finally have some spare time to play with the new 2X5 controller!

Quick question, do I set it to simplified or packetised serial?
#8  
@Byrd... Simplified at 38400baud... Dips on the sabertooth are 1,3,6 on or up and the rest down or off....