We’ll learn more about this circuit in this lesson. When the button is pressed, current flows from \(V_\) through the pull-down resistor to GND. In fact, (virtually) no current flows into Pin 2! Why not? We’ll talk about this and more in this lesson!Īnimation shows the Arduino’s built-in LED illuminating when the button on Pin 2 is pressed. Importantly, notice where the current flows when the button is pressed-perhaps surprisingly, it does not flow into Pin 2. Try to understand the why and how of these resistors in your circuits.įor example, in the animation below, we show a button circuit with a pull-down resistor hooked up to Pin 2. However, when using switches with microcontrollers, we’ve found that students often struggle to understand why pull-up or pull-down resistors are necessary. We use switches everyday when we turn on and off our light circuits in our home. Switches themselves are conceptually easy to understand-they are either “closed” or “open”. We’ll cover buttons (aka momentary switches), how to use digital input with the digitalRead function, and pull-up and pull-down resistors. In this lesson, we’ll finally get to build something interactive: turning on an LED with a push button. We assume you’ve already completed the Intro to Arduino Output series. This is the first lesson in the Intro to Arduino Input lesson series. Internal pull-up resistor configuration.Tradeoffs in selecting a pull-down resistor.Calculating tradeoffs in selecting a resistance value.Tradeoffs in selecting a pull-up resistor.What value should I use for my pull-down or pull-up resistors?.An (incorrect) attempt to fix the floating pin.Hooking up digital input with microcontrollers.Using buttons without a microcontroller.Lesson 1: Using buttons Table of Contents L4: Feature Selection and Hyperparameter Tuning.
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