Built-In Sensors

Reflectance sensors

Robutek has 8 bottom-facing reflectance sensors for line following and surface detection.

How they work

Each sensor shines infrared light onto the surface and measures the reflected intensity.

• lighter surface -> higher value
• darker surface -> lower value

The numeric range depends on the firmware and ADC configuration. A typical range with 10-bit reads is approximately 0..1023.

Electrical structure

The sensors are split into two banks of four:

• bank A: sensors in the front / line area
• bank B: sensors near the wheels

Only one bank is connected to the ADC at a time.

• select bank A by setting IO8 = 1
• select bank B by setting IO8 = 0

After switching banks, wait about 2 ms for the measurement to settle.

IR illumination control

The IR emitters are not permanently active.

• IO47 = 1 turns the IR illumination on
• IO47 = 0 turns the IR illumination off

If the readings are low or unstable, first check the emitter state.

Practical reading procedure

1. Turn on the IR emitters.
2. Select the sensor bank.
3. Wait about 2 ms.
4. Read the four ADC channels on IO4..IO7.
5. Use the values directly or convert them to calibrated quantities.

Notes

• The result depends on the color and material of the surface.
• The result depends on the distance from the surface.
• Thresholds should be calibrated for the target environment.
• A short startup calibration is recommended for line following.

Wheel encoders

Each motor has a quadrature encoder with two digital channels.

Pin mapping

Encoder	Channel A	Channel B
Left	IO40	IO39
Right	IO41	IO42

What they provide

The encoders provide data for calculating:

• wheel direction
• wheel speed
• traveled distance
• robot heading change

Use: closed-loop speed control, odometry, more precise turns.

User buttons

The board has two built-in buttons:

Button	Pin
Left	IO2
Right	IO0

Electrically, they are digital inputs.

Onboard color sensor

Robutek includes one built-in RGB / color sensor connected to the shared I2C bus.

Bus and addressing

• bus: shared I2C
• SDA = IO10
• SCL = IO3
• onboard sensor address bit: high
• address used by the driver: 0x43

Available channels

The color sensor can measure:

• red
• green
• blue
• infrared component
• clear / unfiltered light

Output model

The driver provides:

• raw 16-bit values of individual channels, or
• calibrated normalized values in the range 0..1

Calibration against white and black reference surfaces is recommended for real use.