ATmega168A Pulse Width Modulation – PWM - Protostack Dimming an incandescent bulb is easy. Simply adjust the current down using a potentiometer and you are done. Dimming an LED is another story entirely. When you reduce current through an LED there are unintended consequences like color shifts and dropouts. A better way is to use Pulse Width Modulation (PWM). With PWM the LED is turned on and off many times per second. LED dimming is not the only application of PWM. Source Code Example 1 The example below produces a PWM waveform with a 20% duty cycle. #include <avr/io.h>#include <util/delay.h> #define LED_PORT PORTC#define LED_PIN 0#define LED_off() LED_PORT&=~_BV(LED_PIN)#define LED_on() LED_PORT|=_BV(LED_PIN)int main (void){ DDRC = 0b10000000; while (1) { LED_on(); _delay_ms(2); LED_off(); _delay_ms(8); } return(0);} For most embedded applications, controlling PWM this way is not practical. PWM output lines on ATmega168A The ATmega168A microcontroller has 3 timers which in turn can control 6 PWM lines. Fun with RGB LEDs Source Code Example 2
Cours Électronique - Apprentissage Facile Retour: Accueil > Cours d'électronique Bases de l'électronique Ce premier cours est une initiation à l'électronique. Ces cours d'introduction à l'électronique présentes les principales formules de l'électronique. Les lois évoquées sont notamment la loi d'ohm, la loi des noeuds et le diviseur de tension. Composants Les composants électroniques Cours de base pour comprendre les fonctions des composants au sein d'un montage électrique, ainsi que leur utilité et les moyens de les catégoriser pour mieux les distinguer les uns des autres. Résistance électronique Ce cours d'initiation sur les résistances, permet de rappeler les grands points fondamentaux de celles-ci. Portes logiques Ce cours vous permet de vous initier en douceur à l'électronique numérique. Amplificateur électronique Les amplificateurs en électronique, sont des systèmes permettant d'augmenter la puissance d'un signal. Condensateur Cours pour comprendre l'utilité et le fonctionnement des condensateurs. LED (Diode Électro-Luminescente)
So You Want to Build Electronics The equipment you need to get started in building electronics. If you look back through the last two years of posts on this blog, you'll see my relatively rapid transition from absolute beginner in electronics to someone who is formidable enough to have their work at least noticed (See HaD every other month). This means I've been fielding a lot of questions from beginners online as to how exactly to get started, and what to buy, and what to do with it. The obvious beginner answers are the juggernaut kits from places like the Maker Shed, and I will never knock them for putting together a perfectly reasonable starter kit (which despite your intuition, is actually reasonably priced), but I've never been really interested in them. So here is a gigantic list of everything I would buy right now to replace my entire workshop if mine were to disappear. Books - Online references will get you far, but the internet still can't beat the cohesiveness of a well-put-together book.
Arduino + Processing – Make a Radar Screen to Visualise Sensor Data from SRF-05 – Part 1: Setting up the Circuit and Outputting Values First things first, we need to build our circuit. This is the easy bit! We’ll be using the Arduino to control a servo that will rotate our sensor around 180 degrees. The Arduino will then send the value from the distance sensor along with the current angle of the servo to the serial port. Before proceeding please take a moment to check out some of my other work with the SRF-05 and servos if you’re unfamiliar with either.Arduino SRF-05 TutorialsArduino Servo Tutorials I’m building this with the SRF-05 ultrasonic range finder/ distance sensor, but because this has a fairly wide field of detection it’s not very precise – I think I’ll end up trying a different range finder maybe an IR one as the SRF-05 works best as a static sensor/ detector, anyway… Arduino Radar Parts list Arduino Radar Servo Circuit Straight forward, we have the Arduino providing power to the breadboard and we have the servo and the SRF-05 sharing this power. Arduino SRF05 Radar Sketch
Arduino’s AnalogWrite – Converting PWM to a Voltage D-A_converter When I first started working with the Arduino platform (it was also my first experience with microcontrollers), I was a little surprised that analogWrite didn’t actually output a voltage, but a PWM (pulse-width modulated) signal. After all, the ATmega had a A-D (analog to digital) converter along with Arduino’s analogRead. The complementary analogWrite function was there, but no D-A (digital to analog) converter on the AVR chip itself. PWM Primer Pulse width modulation (or PWM as it is most commonly known), is a way of encoding a voltage onto a fixed frequency carrier wave. With the need for digital communication, a new modulation technique was invented – PWM. PWM outputs (curtesy arduino.cc) For the Arduino, you write a value from 0 to 255 on a PWM pin, and the Arduino library will cause the pin to output a PWM signal whose on time is in proportion to the value written. When it comes time for us to actually write an output voltage, the 0-255 value lacks meaning. Conclusion
10A H-Bridge Motor Controller - Introduction Motor control is the core heart of robotics. Without locomotion or any movement a robot is dull and lifeless. The H-bridge is a tried and true concept for DC motor control. It allows you to move motors forward, backward and with varying speeds through PWM (pulse with modulation). 10A H-Bridge Test Video 10A H-Bridge Completed 10A H-Bridge PCB And All Parts 10A H-Bridge With PWM Input Purpose & Overview of this project The main goal for this tutorial is to build a 10 AMP motor controller that can control a DC motor with a digital input. Lab 14: Inter-Integrated Circuit (I2C) communication I2C (Inter-Integrated Circuit) is a short distance serial interface that requires only 2 bus lines for data transfer. It was invented by Philips in 1980′s, originally to provide easy on-board communications between a CPU and various peripheral chips in a TV set. Today, it is widely used in varieties of embedded systems to connect low speed peripherals (external EEPROMs, digital sensors, LCD drivers, etc) to the main controller. I2C devices with PICMicro Theory I2C bus has two lines: a serial data line (SDA) and a serial clock line (SCL). Both SCL and SDA lines are open drain drivers, and are therefore, connected to a positive supply voltage through pull-up resistors. Start and Stop conditions Prior to any transaction on the bus, a Start condition is issued by the Master device to inform all the slave devices that something is about to be transmitted on the bus. Signaling for Start and Stop conditions I2C device addressing Data transfer Every byte put on the SDA line must be 8-bits long.
Arduino and the AREF pin Learn how to measure smaller voltages with greater accuracy using your Arduino. This is chapter twenty-two of our huge Arduino tutorial series. Updated 12/12/2013 In this chapter we’ll look at how you can measure smaller voltages with greater accuracy using the analogue input pins on your Arduino or compatible board in conjunction with the AREF pin. However first we’ll do some revision to get you up to speed. Please read this post entirely before working with AREF the first time. Revision You may recall from the first few chapters in our tutorial series that we used the analogRead() function to measure the voltage of an electrical current from sensors and so on using one of the analogue input pins. And when we say the operating voltage – this is the voltage available to the Arduino after the power supply circuitry. This can easily be demonstrated by connecting an Arduino Uno to USB and putting a multimeter set to measure voltage across the 5V and GND pins. So what is AREF? External AREF
Tutorials The most fun you can have (after blinking LEDs) is using sensors to detect whats going on in the world and act on that information. However, all sensors have their own methods of interfacing. That can make them a real pain to work with: some need pull-up resistors, some need certain power supplies, some use lots of power, some don't. Tutorials include: Force sensitive resistor - Used to detect physical pressure such as pinching, squeezing, pushing, brushing.
b e a . s t [an error occurred while processing this directive] Magnetic Levitation using Hall effect Sensor Feedback, and Matched resonant wireless power transfer This work was completed initially for a final project for Joe Paradiso's class MAS.836 - Sensor systems for Interactive Environments, taken Spring 2oo5. Click to watch the following movies:Magnet Levitation Movie [100 megs], or in Small form. Resonant Power Transfer movie [95 megs], or in Small form. Motivation: My goal is to build the subsystems to be able to magnetically [stably] levitate a lightbulb that is powered at all times through the air using a matched resonant air-core transformer. In order to levitate a lightbulb, there are three main systems that needed to be explored and techniques that needed to be developed. Implementation: The general goal setup is as shown to the right. Details of the system components are described below. In order to accomplish this, we build a resonant transformer [shown]. Hall Effect Sensing: Performance: