2.12 Potentiometer and Fan Module
A potentiometer is an analog input device that changes its resistance based on how much the knob is turned. This change is measured as an analog value between 0 and 4095. It is commonly used to control other components such as LEDs or motors in a gradual, user-controlled way.
A fan module is an output device that uses a small DC motor to generate airflow. It can be turned on, off, or have its speed adjusted using a digital or PWM signal, making it useful in interactive electronics and smart cooling systems.
Example Applications:
- Adjusting LED brightness
- Controlling motor or fan speed
- Building user-controlled interfaces
2.12.1 Example Code for the Potentiometer
The light sensor outputs an analog value (typically between 0 and 4095) based on the surrounding light. In this example, we check if the brightness exceeds a threshold (4080) to turn on a yellow lamp.
- Hardware Setup:
- Connect a potentiometer to analog pin
P0. - Attacha Piranha LED to
P15, and a fan module toP16.
- Connect a potentiometer to analog pin
- Programming Steps (Block-Based):
- LED Brightness: Set the LED intensity on
P15using the potentiometer value (set LED on P15 output read POTENTIOMETER on P0). - Fan Speed: Adjust the fan speed on
P16proportionally to the potentiometer reading (set Fan on P16 output read POTENTIOMETER on P0). - Display Value: Map the raw potentiometer range
[0, 4095]to[0, 100]and show it on-screen (screen display text map...).
- LED Brightness: Set the LED intensity on
- Key Notes:
- The potentiometer’s 12-bit analog input (0–4095) is scaled to 0–100% for readability.
- All outputs (servo, LED, fan) react simultaneously to the potentiometer’s position.
Figure 2.12.1a: Potentiometer control logic for LED and fan (block-based)