3-Channel Wide FOV Time-of-Flight Distance Sensor Using OPT3101 (No Headers) Pololu

DESCRIPTION

This board is a 3-channel time-of-flight proximity and distance sensor module based on the OPT3101 IC from Texas Instruments. Unlike conventional IR sensors that use the intensity of reflected light to estimate the distance to an object, this board emits 940 nm infrared light pulsed at 10 MHz, and then measures the phase (delay) of the reflected signal, which corresponds to the distance to the target object. It also measures the amplitude of the signal, which indicates how bright/reflective/close the object is. This board has three channels that each cover approximately 50° to 60°, giving the sensor a wide field of view (FOV). In favourable conditions, the sensor can measure objects at distances up to 1 m. Distance measurements are available through the sensor’s I²C interface, which is also used to configure the sensor.

This module is designed to be mounted onto the 7-pin connector on the front of a TI-RSLK MAX chassis board, but it can be used with any I²C-capable device. The board can be powered from a 2.5 V to 5.5 V supply. On-board regulators supply the 3.3 V logic voltage to the OPT3101. The board includes a circuit that shifts the I²C clock and data lines to the same logic voltage level as the supplied VIN, making it simple to interface the board with 3.3 V or 5 V systems, and the board’s 0.1″ pin spacing makes it easy to use with standard solderless breadboards and 0.1″ perfboards.

Please Note:

• Does not include any headers

FEATURES

Specifications

• Dimensions: 1.1″ × 1.2″ (27.9 mm × 30.5 mm)
• Weight without header pins: 2.7 g (0.095 oz)
• Operating voltage: 2.5 V to 5.5 V
• Sensor channels: 3 (each with an FOV of approximately 50° – 60° for a combined FOV of nearly 180°)
• Supply current: 130 mA (typical average during operation in high-brightness mode with 3.3 V power supply)
• Distance measuring range: up to 1 m (3.3 ft) (depends on the target object)

Connections

Four connections are necessary to use the OPT3101 board: GND, VIN, SDA, and SCL. The VIN pin should be connected to a 2.5 V to 5.5 V source, and GND should be connected to 0 volts. The board’s I²C pins (SCL and SDA) should be connected to an I²C bus operating at the same logic level as VIN.

Pinout

• GND – The ground (0 V) connection for your power supply. Your I²C control source must also share a common ground with this board.
• VIN – This is the main 2.5 V to 5.5 V power supply connection.
• SDA – Level-shifted I²C data line: high is VIN, low is 0 V. Pulled up to VIN with a 10kΩ pull-up resistor.
• SCL – Level-shifted I²C clock line: high is VIN, low is 0 V. Pulled up to VIN with a 10kΩ pull-up resistor.
• GP1 – Configurable 3.3 V I/O pin. (This pin is not level-shifted.)
• GP2 – Configurable 3.3 V I/O pin. (This pin is not level-shifted.)
• RST/MS – Input pin that can be used to reset the board or trigger a new sample. (Both of those functions can also be done with I²C.) Pulled up to 3.3 V with a 10kΩ pull-up resistor. (This pin is not level-shifted)

A detailed explanation of the I²C interface on the OPT3101 can be found in the “I2C slave” section of the OPT3101 datasheet

Configuration

The main configuration options that you can choose for the OPT3101 are the channel, brightness, and sample rate. These options are set over I²C, and you can change them between samples. The channel setting determines which pair of IR LEDs will turn on, and thus determines the direction in which the sensor will be most sensitive to objects. There are three channels: TX0 (left), TX1 (middle), and TX2 (right). There are two brightness settings available for the IR LEDs: low and high (also known as HDR0 and HDR1, respectively). Low brightness mode only works well for nearby objects (within about 20 cm). High brightness mode works for longer ranges, but objects that are too reflective or too close can cause the sensor to saturate, meaning that it fails to measure a distance. You can configure the OPT3101 to use one of these brightnesses, or you can make it use an adaptive brightness mode, where it automatically selects between low or high brightness. The measurements performed by the OPT3101 are divided into basic units called a frame or a sample. Each frame has a specific configuration, but you can change the configuration between frames. You can configure the OPT3101 to start frames continuously, or to wait for your signal before starting a frame (which is called monoshot mode). When a frame is complete, you can read its results from the OPT3101’s output registers. Each frame consists of a configurable number of subframes that take 0.25 ms each. The results from each subframe are averaged together. By increasing the number of subframes, you can decrease the noise of your measurements, but the frames will be slower. The number of subframes can be any power of 2 from 1 to 4096.

RESOURCES

• Schematic diagram of the 3-Channel Wide FOV Time-of-Flight Distance Sensor Using OPT3101
• Dimension diagram of the 3-Channel Wide FOV Time-of-Flight Distance Sensor Using OPT3101
• 3D model of the 3-Channel Wide FOV Time-of-Flight Distance Sensor Using OPT3101
• Drill guide for the 3-Channel Wide FOV Time-of-Flight Distance Sensor Using OPT3101
• 3D-printable clip set for securing the 3-Channel Wide FOV Time-of-Flight Distance Sensor Using OPT3101 to the TI-RSLK MAX
• UM10204 I²C-bus specification and user manual
• OPT3101 library for Arduino
• OPT3101 datasheet