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Description: Knowing where your robot is can be very important! The RedBot Wheel Encoder allows you to track the number of revolutions each wheel has made. This sensor works by detecting the movement of small teeth connected to a motor through the reflection of infrared light. By measuring the amount of reflected infrared light you can tell not only how far each wheel has traveled but how fast the wheels are turning.

The encoder has a 6-pin header which connects directly to the RedBot Mainboard via female to female jumper wires. Use the included RedBot library to start detecting wheel measurments. Two mounting holes lets you easily connect this sensor to your robot chassis.

Check out the entire RedBot family of products!

Dimensions: 1.57 x 0.87 " (40.07 x 22.32 mm)

Features:

  • 5VDC operating voltage
  • 2x Mounting Holes
  • 2 Digital Outputs
  • Non-Quadrature

Documents:

Comments 23 comments

  • Is it possible to DOUBLE the resolution of the encoder by switching the Interrupt trigger (in the setPinChangeInterrupt routine) between Falling and Rising Edge in the interrupt?

    For example when the Rising edge is detected and the interrupt routine is entered, switch the interrupt type to Falling edge for the next transition.

    Edit: I see now that an interrupt option exists for “either” edge.

    • Yes, depending on which interrupts you use. The RedBot library uses the pin change interrupt, which happens on either transition; as it turns out, the nature of the reflective sensor and the wheel encoder can cause some ringing at transitions, which makes it important to do some software filtering.

      There’s no reason you can’t do that, just be careful to only capture one edge at a time.

  • Stupid question incoming: How do I mount this on the chassis?

    So far all I’ve been able to figure out is: use two nuts to elevate the board far enough from the teeth so there’s no contact, and screw it in. Is there a “proper” way of mounting this that is consistent with any assumptions in the library code?

    Thanks.

  • How do you use this? What I mean is, if I wanted to use this with something other than a RedBot Board, say a Raspberry Pi. How would I capture the input from the pins?

  • sigh. I’m sure you are sick of hearing this. Any plans on clearing out backorder anytime soon?

    -PJ

  • Hi,

    This is out of stock now… are you planning to build more and when?

    Thanks

    • We’ll have more built up and restocked today. But they are likely to sell out very quickly. If you need one of these soon, I recommend placing a backorder. Once today’s batch is built up, production of more will be on hold until we receive a fresh round of PCBs from our PCB fabricator.

      • I had put one on backorder on 2/1 according to my account, and paid in full. I don’t see any notification yet. Did my order somehow get skipped, or maybe it is still processing? Thanks!

        • We looked into it and your order was printed out this morning by our order pickers. It should be shipping out today or tomorrow, at the very latest. Congrats on being one of the lucky few to get one from the first batch of these wheel encoder boards!

      • Thanks very much for the information.

        I requested a distributor in Madrid, Spain to try to get this encoder so I can buy it directly from them. They told me they have asked Sparkfun for an estimated delivery date, so I truly hope they can manage to get the part once it is restocked today.

        Thanks very much!

  • For best performance, I’m pretty sure that those sensors should be turned 90 degrees so that the edge of the encoder tooth crosses the center-line of both the emitter and detector at the same time.

  • hii I am from India …suggest any distributor which sells this product….in India

    • (I am also from India and I use to buy directly from Sparkfun) You can buy directly from Sparkfun or go to distributors tab and type India in search bar.

  • If the QRE1113 has a transistor output, why build the amplifier circuit following the reflectance sensor? Why not just route the output from the QRE1113 straight to the microcontroller (an ATmega in this case, right?) - The transistor should only drop about 0.7V, right? Or am I missing something really basic?

    • Its not an amp circuit, its a pulse shaper/conditioner actually. Its also acting as an inverter. True you can program to whatever levels you need to work with, but from my reading of things this is being used to activate an interrupt routine to count pulses for the wheel revolution. In these cases its usually good to create a known pulsewidth as opposed to taking a variable signal direct from the phototransistor, which could vary depending on how close or far the unit is from the encoder wheel.

      Additionally also note these are not quadrature detectors, that could tell you which way an unknown wheel is turning, but a simple pulse counter as wheel direction is known from the drive command.

      • In fact, if you use the RedBot library, the encoder counts are automatically updated by interrupts and incremented and decremented according to which direction the motors are turning.

  • Hello, Is there any way that this can be shipped to S. Korea?


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