Jonathan, I have my polulo QTR-8RC sensor connected to the arduino with proper connections and code in order to calibrate. However when I begin my calibration by putting a white piece of paper and a black line on top of it and move it underneath the sensors, the values are only 0 0 0 0 0 0 . Please reply back as I need to calibrate my sensors to make a line following robot
I am sorry you are having trouble getting good data from your QTR sensor. Can you tell me more about your system? Which Arduino are you using? How are you supplying power to your QTR array? Can you try running QTRRCRawValuesExample.ino and post a sample of the raw values you get? Can you also post pictures that clearly show your connections and white paper with black line?
-Jon
Im having a problem where all my connections/soldering/programming is right however it still comes up all zeros. Ive tried the qtrc values examples, but it only shows 2500. PLS HELP!!!
I moved your post back to this thread since it is about the same issue. If you answer the rest of my questions and post pictures, we can continue troubleshooting.
-Jon
those were my connections , then this happened when i did my second run:
for my code i used the examples
for my code i used the examples
It seems like the problem could be that the QTR sensors are too far away from the surface you are sensing, since it looks like each sensor on your board typically reads 2500, the maximum value. Also, you soldered the headers into the board on the same side as the sensors, which looks like it could be making it difficult to lower the QTR sensors close enough to be effective. The optimal sensing distance for the QTR-8RC is 3mm and the maximum recommended sensing distance is 9.5mm. If you are not already, can try obtaining your measurements with the face of the QTR sensors about 3mm from the surface of the paper you are sensing?
Also, some of the soldered joints in your pictures do not look like they are making good electrical connection, and they could be causing an issue. If you are still getting the same readings when your sensor is at an appropriate height relative to the white paper and black line, you might try touching up those joints. I recommend looking at this Adafruit guide to soldering, which should help you identify which joints are not ideal.
Finally, another thing you might check is that the Arduino pins you are connecting to match the pins you are using in the QTR example sketches.
-Jon
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My sensors are all reading zeroes again , so you are saying it must be a soldering problem right?
It could be that soldering is the issue. Have you tried touching up the joints? If so, and things are still not working, can you post pictures or a video that shows what they look like?
-Jon
Dear Jonathan,
Sorry for not replying earlier. Here I have re-soldered the joints and now I am getting some results. Please check if the method that I am using is correct. Please reply as soon as you can. Thanks! Appreciate all your help so far thank you soooo much!
for some reason the video is not uploading so instead i have uploaded on youtube here:
Your new soldered joints look much better!
I think the method you are using to calibrate could be improved. First, the QTR array is oriented in a position where the sensors are facing upwards, which exposes them to all of the ambient IR light in your environment. Also, it looks like the piece of paper you are using warps and distorts as you move it across the sensor array, which changes the distance between it and each sensor. I recommend laying the paper flat on your table (with the black tape facing up, of course) and with your hand, moving the sensor array (with sensors facing down, towards the paper) back and forth. The optimal sensing height is 3mm (0.125"), so try to hold sensor level at that height as you calibrate.
-Jon
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Dear Jon,
Thanks so much I am finally getting the right results,
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Hii Jon , i have recently purchased the QTR 8rc sensor and while running the QTR8rcexamples it shows always 0 in one of the rows is it right reading???one of the rows is always 0 while others show right values.
Hello.
It would help to know more details about the rest of your system. It sounds like you might be using our Arduino libraries; which Arduino are you using? How are you supplying power to your QTR-8RC? Can you post pictures that show your connections and soldered joints? Since the issue you are getting is for a single sensor, it might also help to see pictures of your setup or a video that shows the your system and the behavior you are noticing.
-Jon
Sorry for inactivity
I am using Arduino uno r3
And using your QTR libraries first i tried to run the sensor on QTRRCRAWEXAMPLES.
Then tried using QTRRCEXAMPLES
Here are some pics
Connection:
Sensor pin1 to 8: arduino digital pin 1 to 8
And i connected arduino GND and +5V to sensors GND and 5V.
And connected my Arduino UNO r3 board to computer to get reading via printer cable
Hello.
Which sensor on the QTR-8RC board is always reading 0? Did you change the pin numbers for the QTRSensorsRC object in the example code to match your physical connections between the QTR sensor array and Arduino Uno? If not, can you change your connections to match the code and see if that fixes the problem? By default, the QTRRCExample and QTRRCRawValuesExample use digital pins 3 through 10 to read sensors 0 through 7, respectively. This is stated in the code comments.
- Amanda
hey i have a prblem in reading values i tried with white paper and black paper but all values are same why i use QTRRCRawValuesExample in qtr libary.i include photos in this post please give me a good solution.thank
Can you post pictures showing the top-side of the QTR-8RC sensor array, particularly the soldering on the board, and the connections between the sensor array and your microcontroller? Also, can you try to use your phone’s camera to verify that each sensor on the board is emitting IR light (for many cameras it should show as purple light)? Do you see any changes to the sensor readings if you point them toward the sun?
- Amanda