This is a very simple capacity tester. It consists of single resistor that discharges battery. Arduino measures the voltage drop across resistor. According to Ohm’s Law current = voltage/resistance. Every second value of current is divided by 3600 and summed up to get the capacity expressed in Ah (Amp per hour).
I have used two parallel connected resistors that total resistance is 6.9 ohm. Make sure that they have proper power rating, if you don’t want them to convert to smoke. If voltage across 6.9 ohm resistor is 3.7 V, then current – 0.54 A, power ~ 2W.
Arduino Lithium-ion battery capacity tester/discharge monitor - [Link]
Did you know each Arduino has a unique serial number in its USB interface that you can use to distinguish one Arduino from another? If you deal with multiple Arduinos, knowing exactly which one is plugged into your computer can be a real time-saver. But actually getting at this serial number and mapping it to COM ports can be challenging. For Windows computers, here’s “listComPorts”, implemented both in GCC C code and in VBScript, both available from my usbSearch github repository.
listComPorts – Windows command-line tool for USB-to-serial - [Link]
I was looking for, what I thought, was a simple clock/timer design. Something with a remote and a big display that could be read from across the gym and that I could program with up/down counting but also intervals specific to CrossFit like Fight Gone Bad or tabatas. I wanted to incorporate a bell to give it a gym feel and something that could be heard over loud music. This journey took me through many designs, chips, a custom board, wood working and a whole lot of learning!
Arduino CrossFit Timer - [Link]
Luca explains how to boot your PC with a Wake on Lan command sent from an Arduino. Setup the WOL feature on your PC, then use the sendWOL() command to send a magic packet via and ENC28J60 ethernet chip: [via]
The wake command is issued sending on the network a specific packet, called Magic Packet. This packet is receved by all the devices connected to local network because it presents – as destination MAC address – the broadcast address (FF:FF:FF:FF:FF:FF). It includes six bytes valued FF, followed by the target PC’s MAC address repeated 16 times.
Boot your PC with the Arduino using the Wake on Lan command - [Link]
We want to show you how to use the popular Arduino to produce a device capable of recognizing passive transponder (TAG). But this is not the usual RFID key, because the system can activate a relay if a recognised TAG is read, but also we took the opportunity to make an application that use cloud-computing. The basic version, which is a simple key relay consists of an Arduino and the RFID shield based on a ID-12 of Innovations: placing a transponder already learned, the relay is activated. The extended version of our project uses an Arduino, the RFID Shield and the Ethernet Shield with which we can access the Internet and stored, using the Google Docs service, the transponder data.
Arduino RFID shield on the Cloud - [Link]
A lot of people who bought the TiDiGino ask me how to test it. The Gsm Remote Control is provided with bootloader, so you have to insert the prefered sketch that you can find in code.google. Daniele Denaro wrote a good sketch for TiDiGino, and I’m reporting his tutorial. Ask me (and him) all do you need.
Author Daniele Denaro
Be careful, because you have to manipulate the environment of development (IDE) 1.0 to insert the new hardware. In particular replace the file “boards.txt” (see below). In this new version of the file has been added to the section on hardware TiDiGino. You should also add the folder “tidigino” that “boards.txt” references (see below). The changes will be visible to restart the IDE.
Software and firmware for TiDiGino - [Link]
Kerry uses a DIY serial display to show debugging data sent from an Arduino’s UART. Sometimes the data comes too fast to read, so he added a 4K buffer and controls to scroll thorough the history. [via]
…if your application generates a lot of messages, it would still be hard to spot the relevant information as you can only see the last couple of lines of the data.
So my solution is to add a none-volatile off-screen buffer to the serial display so that multiple rows of data can be captured during run time and retained for later debugging.
Serial port monitor with 2×20 LCD and 4K text buffer - [Link]
I wanted to make an easy and secure way to enter my garage. RFID was the best way to unlock my door, even with my hands full I can unlock the door and push it open! I built a simple circuit with a basic ATMega 168 arduino chip and a ID-20 RFID reader to control an electronic door lock.
The circuit consists of 3 separate parts, a Reader to read RFID tags, a Controller to accept data from the reader and control the output of the RGB LED and the Electric door lock. The door lock is first installed in a door and tested with a 9v battery to ensure correct installation. In most cases you want a Normally Open circuit on the door lock, or Fail Secure. This means the door stays locked when no current passes through it. When 12vDC is passed through the electromagnet in the door lock, a plate in the lock gives way and allows the door to be pushed open freely.
Arduino RFID Door Lock - [Link]
This segment is the latest in a series of Arduino tutorials posted by Tronixstuff.
Tutorial: using Ping ultrasonic sensor with Arduino - [Link]
Digital pins 0-7, Analog 2-5, and a RST, V+, and GND pin are broken out to two rows of pins, maintaining about half the pins in a familiar shape and organization. A JST connector for LiPo batteries like the ones available through SparkFun and Adafruit and an MCP73811/2 charger circuit makes the Demiduino well suited for portable applications. On the back, I’ve also included CR1225 clips for ~3v3 power from easy to find coin cell batteries, and a power switch to save battery life.
Demiduino, another tiny Arduino compatible board - [Link]