QTR-8RC Reflectance Sensor Array - Digital

QTR-8RC Reflectance Sensor Array - Digital info

QTR-8RC Reflectance Sensor Array is intended as a line sensor, but it can be used as a general-purpose proximity or reflectance sensor. The module is a convenient carrier for eight IR emitter and receiver (phototransistor) pairs evenly spaced at intervals of 0.375" (9.525 mm). To use a sensor, you must first charge the output node by applying a voltage to its OUT pin. You can then read the reflectance by withdrawing the externally supplied voltage and timing how long it takes the output voltage to decay due to the integrated phototransistor. Shorter decay time is an indication of greater reflection. This measurement approach has several advantages, especially when coupled with the ability of QTR-8RC Reflectance Sensor Array to turn off LED power:

• No analog-to-digital converter (ADC) is required
• Improved sensitivity over voltage-divider analog output
• Parallel reading of multiple sensors is possible with most microcontrollers
• Parallel reading allows optimized use of LED power enable option

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.

QTR-8RC Reflectance Sensor Array - Digital  - General Specifications

• Line sensor
• General purpose proximity or reflectance sensor
• 8 IR emitter and receiver pairs
• No ADC required
• Improved sensitivity
• Parallel sensor readings possible
• Maximum 9.5mm sensing range

QTR-8RC Reflectance Sensor Array - Digital - Technical Specifications

• Dimensions: 2.95" x 0.5" x 0.125" (without header pins installed)
• Operating voltage: 3.3-5.0 V
• Supply current: 100 mA
• Output format: 8 digital I/O-compatible signals that can be read as a timed high pulse
• Optimal sensing distance: 3 mm
• Maximum recommended sensing distance: 9.5 mm
• Weight without header pins: 3.09 g

Videos

Documents

QTR-8A and QTR-8RC Reflectance Sensor Array User’s Guide: https://www.pololu.com/docs/0J12

Pololu QTR Reflectance Sensor Application Note: https://www.pololu.com/docs/0J13

Pololu AVR C/C++ Library User’s Guide: https://www.pololu.com/docs/0J20

Arduino Library for the Pololu QTR Reflectance Sensors: https://www.pololu.com/docs/0J19

Pololu AVR Library Command Reference: https://www.pololu.com/docs/0J18

References

Pololu Web Site: https://www.pololu.com/product/961