QTR-8A Reflectance Sensor Array
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, allowing the LEDs to be turned off by setting the MOSFET gate to a low voltage. Turning the LEDs off might be advantageous for limiting power consumption when the sensors are not in use or for varying the effective brightness of the LEDs through PWM control.
The LED current-limiting resistors for 5 V operation are arranged in two stages; this allows a simple bypass of one stage to enable operation at 3.3 V. The LED current is approximately 20-25 mA, making the total board consumption just under 100 mA.
Features:
- Dimensions: 75x 13x3 mm
- Operating Voltage: 3.3-5.0 V
- Current Draw: 100 mA
- Otput Type: 8 Analog Voltage
- Output Voltage Range: 0V to Vcc
- Optimal Sensing Distance: 3 mm
- Maximum Sensing Distance: 6 mm
- Weight: 3,09 gr.
There are several ways you can interface with the QTR-8A outputs:
- Use a microcontroller’s analog-to-digital converter (ADC) to measure the 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 the digital I/O line of a microcontroller.
- Connect each output directly to a digital I/O line of a microcontroller and rely upon its internal comparator.