Asked — Edited

H-Bridge Wiring And Using A Motor/Gearbox Combo

Hello DJ Sures!

Got a few questions for you from a robotics newbie:

First, could you breakdown the wiring of the Sparkfun Dual Motor Driver? I saw the new video that was posted but still couldn't follow the wire to port progression. I tried looking at the schematic for the driver but there were more ports on that than the chip! So, could you break it down even further, ie POS, GRD, and SIG, to which chip port?

Second, I want to use the Tamiya 70168 double gearbox and dual motor setup for my first EZ-B project. Do you have any warnings and/or suggestions for this setup?

Thanks in advance for any help!


Upgrade to ARC Pro

Stay on the cutting edge of robotics with ARC Pro, guaranteeing that your robot is always ahead of the game.


Hey dude! There is a tutorial under Hardware Tutorials on the forum. The link is here: Clickity Click

That gearbox is pretty quick. It isn't very torquey (is that a word?). So you might have your bot flying around. You can moderate the speed by connecting the PWM pin of the hbridge to any of the Digital Pins on the EZ-B. Then configure that digital pin to be a servo. The higher the servo, the more PWM will be sent. But, i'll warn you that it won't have much torque at a low rpm.

For the cost of that gearbox, it is a great bang for the buck.

The reason I use modified servos often for my projects is speed and torque. I am familiar with them and always know what kind of speed i'll get from my bot:) .. But, since you sound adventurous, GO FOR IT! It'll be great to see what your results are.

I'm certain your results will be appreciated by everyone on this forum. Including myself!

Any hints on what you're going to make yet?


Thanks for your quick and informative response!

Of course, I have a few more questions. From the video and the pics, are PWMA and PWMB jumpered together, then fed +5 from the EZ-B? For speed variation, I would wire PWMA and PWMB seperately, then connect to EZ-B?

I want to do a simple tank track setup and add the launching mechanism from an impulse buy Nerf suction cup/soft dart gun. Not gonna move to any kind of sensor inputs till I get motion down comfortably.

Still waiting for the EZ-B from Solarbotics with other goodies, but i will post pics as i progress, as i will likey have more questions.

Thanks for making robotics fun and accessible!


Hey DJ!

Got a question for you. Ok so i got my ez-b controller with some other accesories, a few of them being a sparkfun dual motor hbridge and the tamiya twin-motor gear box. After wiring everything according to your instructions i have encountered something that may or may not be normal ops. when I use the hbridge controls to control movement, everything works great. Except, when going in forward motion i hit the reverse button, the motor stops and the controller drops connection with the computer, the same is true for left to right motion. when i try to reconnect, the computer is unable to do so and i have to restart the ez-b controller. before restart, the blue led is blinking and the red is steady.

my question: do i have to hit the stop button before any other movement is initiated?


Sounds like your batteries might not be great. Also, check that the power to the HBridge for the motor is coming from the batteries directly and not off the EZ-B +5.

There are two power sources to the HBridge. One is for the HBridge chip itself, that requires +5. The other is for the Motors, and that should be hooked directly to your battery.

What you are experiencing is a brown-out. You should not have to hit stop before changing directions.

Also, if your motors are causing reverse polarity short in the circuit, you might need a diode feeding the HBridge to protect the polarity. First check your wiring for the first suggestion.


Did someone say they needed a better battery?

You mean like one of them there EZ-Batteries?