Tech Thursday

Encoder support starts with SuperDroid Robots

There is a lot to know about encoders along with how and when to use them.  This post is intended to summarize all the past posts we have made the involve encoders and shed some more information/support on the topic.

Motors with Encoders

Most of our robot kits allow you to select the motors you want to used to drive the robot. The options will include motors with encoders. Encoders are very useful if you are planning on making your robot semi-autonomous or fully autonomous. Our motors use hall-effect encoders, which require some special consideration. Hall effect encoders require pull up resistors. We have made the process of pulling up the encoders very easy with our encoder pull-up board. You will need one encoder pull up board per motors. With 4WD or 6WD motors you typically only need to hook up one motor per side to read the encoders unless you are planning to used multiple motor controllers. So the motor power is run in parallel for the right side and the left side and just hook up the front motor encoders.

Counting the Pulses

After the encoders have been pulled up the next decision is what to do with the encoder signal. There are multiple ways to do this. One method is to read the encoders into your computer or micro controller after the signal has been pulled up. If you are using a computer or micro controller directly, you will need to put the encoder pulses on interrupt lines to ensure you don’t miss any pulses. You will also need to make sure your micro controller or computer are fast enough to catch all the pulses There are two encoders per motor (an A and B channel), this allows quadrature counting and the direction of the motor and be determined. All this is rather involved. A much easier method to read the encoder pulses is to use our Dual Encoder Buffer Board. The buffer board takes care of everything for you, it reads both channels, buffers the count, pulls up the encoders (you don’t need the extra hardware of the encoder pull-up board with the buffer board) and you just use your computer or micro controller to pole the buffer board for the encoder count when its convenient. One additional piece of equipment we have on our site to make hookup easier is the Encoder Buffer Hookup Kit

Encoder Support

Components for Reading Encoders

Controlling the Motors

If you want to add speed control to your motors or set the robot to run a set distance and stop, you can do that by reading the pulses as discussed above and then command the motors with the appropriate action. This is sometimes not as responsive as you may like depending on the speed of your computer or micro controller. The other method is to let the motor controller do all the work for you. This requires a fair amount of setup with the motors controllers. The motor controllers that have encoder support build in will state it in the item description. The Dimension Engineering Sabertooth Motor Controllers do not offer encoder support directly, but you can add the Kangaroo. Again, it is necessary to use encoder pull-up boards on our hall effect encoders. The Kangaroo requires a USB to TTL converter to set it up, or the DELink2 USB Link

Encoder Support

Motor controllers for encoder control

  • Kangaroo x2 motion controller: Kangaroo x2 adds self-tuning feedback motion control to your Sabertooth or SyRen motor driver. It can be used with quadrature encoders or potentiometers to provide position or speed control.
  • DELink 2 USB link: The DELink 2 USB Link by Dimension Engineering, is the perfect compliment to program the kangaroo motion controller. Coupled with the DELink Software, you can design, test, and preview your settings with ease.

Additional Posts and Encoder Support


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