Asked — Edited

Help Please Ez B Keeps Disconnecting

Can anyone help me.

I am having an issue where I am using a TTL serial board with a Micro USB that is connecting to the EZB instead of the blue tooth.

I am having issues where I am connected and things are all good but then sometime it spontainiously disconnecting or unable to connect.

Sometimes if I switch usb ports it connects but will disconnect really quick.

Here is a brief description of my setup.

EZB v3.5 board

Micro USB to TTL Serial Adapter board

Sabretooth 25 amp Motor Controler setup as serial connected to 2 jazzy scooter wheels (Setup as my Movement panel)

L298 Motor controler setup as Digital on /off controling 2 actuators for the arms.

Power is provided by 2 12v gel batteries connected to a inverter for the adapters (Reason for the adapters is that some of the AV equip needs special power)

new USB Cable

Power to the EZ B is provided from the USB adapter and also a 12v 2A ac adapter.

Blue Tooth Adapter connecting a sony playstation Navigator controler.

As a Note of interest I have had this exact setup other then the playstation controler working in another bot with no issues.

The only difference is that I am using 12v before I supplied 5v to the EZB.

Any Advice would be greatly appreciated.

I need to get this done by Thursday. Thanks as always to the great EZB community


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Hi @Woodylv the first thing I would check is if your Grounds (negative reference) are all tied together.

Here are a few clarification questions for you:

Does your setup spontaneously disconnect while moving or stationary?

How hot are your EZ-B regulators getting?

Do you have any pictures of your setup and how the adapter board is hooked up to the EZ-Bv3?

Do you also have links to some of the items like the TTL serial adapter board?

Is your USB cable grounded to the shield of the cable (outer metal on connectors)? You may be isolating the grounds from each other with the USB cable. I've have USB cables that have had issues like this, I would try another.

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Also, if none of @skater_j10's suggestions work, check that the 2A your battery to the EZ-B is enough to power everything that's coming off of it, you may be browning out.


I have found that USB to serial adapters in my experience do not work all that well. I have tried to use a few in the past with a pc that didn't have a serial port to connect to my basic atom pro without success. I eventually gave up and bought a computer with a 9 pin dedicated serial port...


Ok So Skater thanls for the Reply.

I have the grounds from my motor controlers running to ground pins on the EZB.

Also it can be moving or stationary when it disconnects.

The regulators dont seem to be getting hot at all. I was worried that the 12v 2A might not be enough power. Do you think I could just run it directly off the 2 batterys which are in parralel ?

I have tried a few usb cables but as far as I know the cable is just grounded internally. There are no extra ground wires on the cable so I would assume that it is grounded to the shield and frame of the connector.

Here is a link to the TTL Board

Just a reference I have this setup on another and it seems to be fine. I also troed another USB TTL same kind and it did same thing.

I had a straight through cable on it and it was working just fine but the cable was too short so I got this 10 foot one.

I thought that the arms which were binding up maybe were causing a brown out but I fixed the binding.

Also my power terminals are right by the board so I could just go right to the board from the battery.

Side Question....Can I run my grounds directly to the negative battery terminal ? instead of the EZ B? The Sabretooth has a seperate ground (0V) spot on the logic side but the L298 for the arms does not. I have to squeze it in the same as the 0V comming from the battery. (So I would assume that its already referencing this)

Here are some pics.

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@woodylv Thanks for the pictures, yep I would definitely try and replace the 12V AC adapter with 12V from the battery and see if that helps. I have found that sometimes AC adapters just don't cut it when there is a sudden demand in current.

A couple more clarifications:

-Does the whole EZ-B seem to reset or is it just your serial connection cutting out? -Does the disconnect happen when the L298 wants to move the arms? Or does it seem pretty random? -Normally can you wiggle the connection points between the EZ-B and the serial adapter without seeing it disconnect?

Edit - Sorry and yes you can have the grounds meet at the negative battery terminal that's probably ideal.


Just the serial connection it seems. The blue light starts blinking again and sometimes I can just change USB ports and it reconnects.

It seemed at first to be related to the arms but sometimes it disconnects with out even moving them. But it does disconnect when the arms bind too. which I fixed

But it is kind of random

I will bring in the 12v from the battery but do I have to worry about over powering the EZB ?

Also I will fix the grounds to the negative terminal.

Also I have the connectors hot glues for the serial adapter and then the other end is soldered terminals that are solid so not much wiggle.

Thanks again for the help. and I will let you know how this works.


EZ-B can take way more than 12 volts, so no worry about overpowering. Do monitor the heat on the voltage regulators. If they get really hot, you may want to put a regulator between the EZ-B and the battery, but probably more than 2A.




Should Amperage be an Issue ?

Might sound like a stupid question but if I remember correctly the board should only use as much amperage as it needs.


If I'm reading this right you were only feeding the EZB 5vdc? I think that's may be to low. I feed 12vdc to all my EZB's and have never had a power porblem. These little control boards will accept up to 17vdc. As mentioned, try a power supply instead of your battires to see if that solves your problems. Also make sure all your connections and wires are tight and true.


@wodylv, Correct, the board will only pull the amps it needs. Only thing with high amps is be really careful making your connections and not arcing or you can easily blow things up.



Hey guys i just thought of something we encountered in another thread, remember that you won't need the VCC connection from the serial adapter plugged into the EZ-B as the computer and EZ-B will both be supplying 5V at that point so it may be causing issues as they both try to provide a stable 5V to the circuit. I would just remove that connection and keep the computer 5V and EZ-B 5V separate, grounds still need to be hooked together though.


Thanks for the great info guys and I will let you know how it goes tonight.

I am definitely separating the 5 volts from the computer and I am going to run the 12v right from the batteries to the EZB.

Worse comes to worse I still have my Bluetooth mod that I can use but my sony PS3 controller hijacks one whole blutooth adapter so I will need to add another.

And I am going to run my ground from the sabre tooth directly to my negative terminal.

The L298 uses the 12V from the battery for power and logic so I am assuming that the negative on that is already the ground.

Thanks again everyone for your input. It has to be something stupid I am sure.


mine would not connect to EZB when the diode on the pc was not soldered in the circuit. But, these other guys are probably right about the voltage and you should get yourself some BUCK regulators if you are going to drive servos.

you might want to re-seat your chips in their sockets.

my 2 cents.