Specification:
- Number of sensors: 3
- Supply voltage: 5 V
- Current consumption: 50 mA
- Outputs: analogue signal (0 - 5 V)
- The optimum distance for measurement: 3 mm
- The maximum distance for measurement: 6 mm
- Dimensions 32 x 8 x 3 mm
- Weight: 0.6 g
The kit includes one module with sensors and two goldpin straps: straight and corner for self-soldering.
Description
Strap is used in robots likeline follower,as sensors, detecting the track as a black line on a white background. The module consists of three reflective sensors that contain the IR transmitting LED and receiver in the form of phototransistor. The output is an analog voltage which can be read using anymicrocontrollerwith an A/C converter, includingArduino.
Between the sensors left is 9.5 mm space so that a strap was reliable on the tracks applied with the standard insulating tape with the width of 19 mm.
Service
There are several solutionsthat allowsto read data from the sensors QTR-3A
- Connecting the outputs tomicrocontroller with analog to digital converter, for example, of the analogArduino pins
- Connecting to the digital inputs viaanalog comparator, to determine the threshold between white and black
- Connecting directly to the digital pins,usingbuilt-inmicrocontrollerinternal comparator
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The product is compatible with Arduino For users ofAVR microcontrollersand modules of Arduino, the manufacturer has prepared special libraries facilitating the usage of sensors: the AVR library,the Arduino library. |
The optimal distance from the surface to the sensors is 3 mm, the maximum, at which the sensor functions, is 6 mm. To picture the situation, we present the oscilograms, showing the detection of black lines on a white background at different distances from the surface.
The analog signal after the detection of black lines on white surgace at a distance of 3 mm on the left, and 9 mm on the right side.
Scheme
Each of phototransistors has pulling-up external resistor, allowing direct connection of the outputs to the microcontroller and the read of the voltage from the range 0 - 5 V that is appropriate for the color and distance from surface.
Current to each transmitting LED was set to 17 mA, what at powering with the voltage of 5 V makes that the average current consumption of the whole module is about 50 mA.
Diagram of the module QTR-3A.
Useful links |
