QTR 8RC Array sensor Question

Is it possible for this sensor to just run without a needed microcontroller? We need to make a line following robot where we don’t use an arduino and i tried testing with the qtr 8rc and it does not work.


It is not clear to me what you mean when you say you want the sensor to “just run” without a microcontroller, but you can find a description of how the sensor works in the “Interfacing the QTR-8RC Outputs to Digital I/O Lines” heading of the QTR-8RC product page. In short, you need to be able to drive the line high, wait for it to rise, then make the line a high impedance input, and then measure the time it takes for the voltage to decay. I do not have any specific recommendations for how to do this without some kind of microcontroller.

Something like the analog QTR-8A version of that sensor (or our newer QTR sensors) might be closer to what you’re looking for. Could you describe in more detail what you are trying to do, including how you tested the sensor, and what you are connecting it to?


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That’ll be cool but I don’t think that’s possible. Maybe you can throw more light on what you’re doing.

Hello I just need to create a simple line follower without the use of microcontrollers so my idea was to make the outputs of atleast 3 of the sensors be the logic for when the motor will run

so its QTR sensor output → motor driver → motors, thats the idea behind it

I tried testing whether or not the qtr 8rc sensors were individually working by supplying current through it vcc and GND and just using one of the output pins (in my case, tried pins 1,3,5) and connecting it to a gate to see whether or not it outputs a 1 or a 0 and its not outputting anything in my end. Any idea where i could be wrong?

It sounds like you are trying to test them by just supplying power and not following the procedure described in the “Interfacing the QTR-8RC Outputs to Digital I/O Lines” heading of the product page as I mentioned in my previous post. To get a reading from each of the outputs, you need to drive the sense line high, wait for it to charge, then switch to a high-impedance input and measure the time it takes for the reading to go low; the measured time is the reading. I do not have any suggestions for achieving this without a microcontroller, and it will not be appropriate as an input signal directly to a motor driver.

You might be able to use an analog version of the QTR sensors to do something like that, but that might also require some additional hardware such as comparators (for example, something like this Analog Line Following Robot blog post on the IEEE website).