![]() ![]() ![]() Before we start writing the software we first need to install the Raspberry Pi GPIO Python module. With the circuit created we need to write the Python script to blink the LED. Writing the Python Software to blink the LED To find the pin number refer to this diagram showing the physical pin numbers on the Raspberry Pi. The long should be connected to the resistor and the short lead should be connected to ground via the blue jumper wire and pin 6 on the Raspberry Pi as shown on the diagram. The long lead is the positive side also called the anode, the short lead is the negative side called the cathode. You will notice that the LED has a long and short lead. When hooking up the circuit note the polarity of the LED. You can use your multimeter to double check the resistor value. To find the right resistor use the resistor color code – for a 100 ohm resistor it needs to be brown-black-brown. The resistor and LED needs to be in series like the diagram below. With the value calculated for the current limiting resistor we can now hook the LED and resistor up to GPIO pin 8 on the Raspberry Pi. Increased current would result in running our system over the maximum rating and potentially destroying or damaging our components. Rounding down instead of up would be dangerous, since it will actually increase the current being drawn. This is good because we don’t want to run our system at the maximum current rating. Important information : Since ohm’s law tells us that I (current) = V (voltage) / R (ohm) rounding up the resistor value will lower the actual current being drawn a little. In this case we would round up to 100 ohm. ![]() To solve this we can either combine multiple resistors, or round up to a standard size. Unfortunately 80 ohm is not a standard size of a resistor. We can then calculate the resistor size needed to limit the current to the LED’s maximum forward current (IF) using ohm’s law like this: Additionally we need to know the output voltage of the Raspberry Pi which is 3.3V. A regular red LED has a forward voltage (VF) of 1.7V and forward current of 20mA (IF). Specifically we need to find the forward voltage (VF) and the forward current (IF). To calculate the resistor value we need to examine the specifications of the LED. Without the resistor the LED would run at too high of a voltage, resulting in too much current being drawn which in turn would instantly burn the LED, and likely also the GPIO port on the Raspberry Pi. The resistor is used to limit the current that is being drawn and is called a current limiting resistor. The first step in this project is to design a simple LED circuit. Then we will make the LED circuit controllable from the Raspberry Pi by connecting the circuit to the general purpose input/output (GPIO) pins on the Raspberry Pi.Ī simple LED circuit consists of a LED and resistor. Raspberry Pi 3 setup with monitor and USB Mouse & Keyboard.We will need the following tools to complete the project: This tutorial will guide you through setting up the circuit, connecting it to the Raspberry Pi and how to write the Python script that makes the LED blink. It makes it possible to jump from one kind of hardware to another with some relatively small modifications to your MicroPython program.A great way to get started with electronics and the Raspberry Pi is hooking up a red LED and making it blink using a Python script. The purpose of these couple of lessons is to show you how versatile MicroPython. In the next lesson I'll show you how to do something similar with the BBC Micro:bit. You can also check the state of the LED by calling the value, but without a parameter. You can also use the "value" function to explicitly control the state of a pin. are targeting GP25Now, that you have this object, you can use the toggle() function to turn it on or off. Next, create the LED object and set pin 25 as an output. So, now, that you have access to the Pin module, you can use the capabilities it provide to do things such as toggle the state of the LED In this case, the machine library contains functions that specifically apply to the Raspberry Pi Pico. It contains functions that are specifically created for the microcontroller that you're targeting. The machine library is a library that is available for all microcontroller units that support MicroPython. First, import the Pin module from the machine library. ![]()
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