QTR-8A Analog Infrared Sensor
It has 8 IR LED / phototransistor pairs mounted 1cm apart and is an excellent detector for line-following robots. It can also be used as a general-purpose proximity or reflection sensor.
The outputs are all independent, but the LEDs are arranged in pairs to halve current consumption. The LEDs are controlled by a MOSFET with a gate normally pulled high, which allows the LEDs to be turned off by setting the MOSFET gate to a low voltage. Turning off the LEDs can be advantageous to limit power consumption when the sensors are not in use or to vary the effective brightness of the LEDs with PWM control.
Each phototransistor creates a voltage divider that produces a voltage voltage between It is connected to a pull-up resistor. 0 V and VIN as a function of reflected IR. Lower output voltage is indicative of higher reflection.
LED current limiting resistors for 5 V operation are arranged in two stages; This allows a simple step to be bypassed to enable operation at 3.3 V.
Schematic Diagram of the Module
Technical Specifications
- Operating voltage: 3.3-5.0V
- Supply current: 100mA
- Output format: 8 analog voltages
- Output voltage range: 0V supplied voltage
- Optimal sensing distance: 3mm
- Maximum recommended sensing distance: 6mm
- Weight without header pins: 3.09g
There are several ways to interface with QTR-8A outputs:
- Use a microcontroller's analog-to-digital converter (ADC) to measure voltages.
- Use a comparator with an adjustable threshold to convert each analog voltage into a digital (i.e. black/white) signal that can be read by a microprocessor's digital I/O line.
- Connect each output directly to a microprocessor's digital I/O line and connect it to its internal comparator. trust it.
Pololu AVR library provides functions that make it easy to use these sensors with robot controllers. For more information QTR library command You can check the section. For the QTR-8A Arduino library,
click
Splitting the Module in Two
If you do not need all eight sensors, you can break two sensors and use all 8 sensors as two separate modules as shown below . Each of the two resulting parts functions as an independent line sensor.
Pololu QTR Sensors Application Notes
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