PCA9550 LED Driver With Programmable Blink Rates

This project introduces the use of PCA9550, an LED driver that causes the 2 LEDs to ON/OFF or in a flashing state at programmable rate. It has 2 selectable, fully programmable blink rates between 0.172Hz and 44Hz or 5.82 seconds and 0.023 second respectively. Its internal oscillator does not require external components and I2c bus interface logic is compatible with SMBus.

The PCA9550 LED blinker drives LEDs in I2C-bus and SMBus applications where it is necessary to limit bus traffic or free up the I2C Master’s (MCU, MPU, DSP chip set, etc.) timer. The uniqueness of this device is the internal oscillator with two programmable blink rates. This LED blinker requires only the initial set-up command to program BLINK RATE 1 and BLINK RATE 2 (i.e., the frequency and duty cycle). From then on, only one command from the bus master is required to turn each individual open-drain output ON, OFF, or to cycle at BLINK RATE 1 or BLINK RATE 2. Maximum output sink current is 25 mA per bit and 50 mA per package. Any bits not used for controlling the LEDs can be used for General Purpose I/O (GPIO) expansion. The active LOW hardware reset pin (RESET) and Power-On Reset (POR) initializes the register to their default state, all zeroes, causing the bits to be set HIGH (LED OFF). One hardware address pin on the PCA9550 allows two devices to operate on the same bus.

LED drivers can enable dimming and color changing or sequencing of LEDs initiated by preset commands, occupant presence, or manual commands. Most LED drivers are compatible with commercially available 0V to 10V control devices and systems like occupancy sensors, photocells, remote controls, architectural and theatrical controls, and building and lighting automation systems.

PCA9550 LED Driver With Programmable Blink Rates – [Link]

Controlling servo motor using IR remote control

by mohamed soliman @ instructables.com:

If you are looking for comfort and controlling your electronic devices remotely, you will find your need in this instructable.

In this instructable we will learn how to control a servo motor with remote control, this will give you a general concept on how to control remotely. You should know that the remote control sends Infrared(IR) signals, so we will learn how to receive and read these signals using Arduino.

Controlling servo motor using IR remote control – [Link]

The Simple Scalar Network Analyzer

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by rheslip.blogspot.com:

After playing around with the SynthNV signal generator/power detector discussed in the previous post I realized what a useful a tool it is for RF testing. While its a terrific tool for VHF/UHF/Microwave testing, the SynthNV has a couple of serious limitations for amateur use in the HF region – the signal generator has a minimum frequency of 35 MHz, the generated signal has a lot of harmonics and its a fairly expensive piece of gear. This project is a fairly simple, very low cost Scalar Network Analyzer that does the same thing in the HF bands from 1MHz to 30MHz. If you buy the parts from China or Ebay and do some scrounging it should cost you less than $20 to build.

The Simple Scalar Network Analyzer – [Link]

Teensy GPS Logger redesigned in smaller version

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The last and final design, the Teensy and GPS is directly powered from 3.7v li-on batt. Arduino code and pcb layout (ARES) available.

Teensy GPS Logger redesigned in smaller version – [Link]

EA DOGS displays – small by size, big by features

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Minimum power consumption, very good legibility and a lot of versions – these are the EA DOG displays.

When we speak about “versions” – in case of EADOG from company Electronic Assembly it means a lot of “glass” types (STM, FSTN, transflective,…) and what is unique – many s display + backlight combinations. Right thanks to this unique possibility to make your own combination display + backlight according to your needs make the EADOG series so versatile. We can find here extraordinarily thin and compact graphic and character displays:

  • 1×8 – 2×16 – 3×16 for +5V or +3.3V power supply
  • 4×10/2×10 – 4×20 for +3.3V
  • Graphic 102×32 .. 240×128 for +3.3V

Character displays are with the SPI interface, some are also with I2C, and 4/8 bit. Simple 3,3V or 5V power supply further simplifies their usage.
In the EADOG family can be found „S“, „M“, „L“ and „XL“ series (EADOGS, EADOGM,…). The smallest one – EADOGS is suitable even for miniature applications, where a place is precious, but still a display is desirable or necessary there. On stock we keep three graphic versions 102*64 px with 33,6*23,4 mm active area. The newest member in the family of these small displays is the EA DOGS104-A character display (4×10 with a small font or 2×10 with a big font), while the character height may be changed by software. EA DOGS104-A is in standard equipped with 3 character sets (EN, EU, cyrilic).

The easiest way how to start development is to use the EA 9780-3USB development board.

EA DOGS displays – small by size, big by features – [Link]

The Atmel SAM L22

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by Martin Cooke @ elektormagazine.com:

Atmel has recently announced the addition of the SAM L22 series to its family of secure, ARM® Cortex® M0+-based MCUs. These new devices offer a built-in, ultra-low power capacitive touch interface with a segment LCD controller that can deliver up to 320 segments. Typical applications for these controllers would include low-power devices such as thermostats, electric/gas/water meters, home control, medical and access systems.

Their inbuilt features make them suited to IoT applications and the SAM L22 series includes security capabilities to deliver 256-bit AES, cyclic redundancy check (CRC), true random number generator, Flash protection and tamper detection to ensure information is securely stored, delivered and accessible. The devices use Atmel’s proprietary picoPower® technologies for low power consumption and smart low-power peripherals that work independently of the CPU in sleep modes.

The Atmel SAM L22 – [Link]

Turn your lights on with clapping?

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by GreatScottLab @ instructables.com:

Wouldn’t it be nice to turn on your lights without getting off the couch? In this project I am going to show you how to build a simple Arduino clap circuit which can turn on and off all kinds of AC appliances. Let’s get started!

Turn your lights on with clapping? – [Link]

Automatic Light Switching System with Dimmer

Manual switching of outdoor lights in houses or roadways can be sometimes really inconvenient especially when we are far away or still at work. Sometimes this becomes an opportunity for thieves to infiltrate houses or a possibility of accident in roadways if night comes and our outdoor lights are still OFF. That is why the goal of this circuit is to automatically switch ON outdoor lights when it senses that it is getting dark and switch OFF lights when it’s daytime.

This type of light switching system is what we can usually see installed in streetlights or houses that are implementing automatic switching of outdoor lights. The system is not just limited to switching ON/OFF lights, it can also adjust the brightness of the lights so that it can just supply the right amount of luminance on the area required. This system is composed of a photocell, a receptacle, a ballast (with dimming control), and a lamp powered by the 220VAC mains. The photocell measures the light intensity level in an area and sends this data in a form of voltages (ranging from 0-10VDC) for the dimming control of the ballast. Based on the level of light intensity sensed by the photocell, the ballast will adjust the brightness of the lamp.

The whole system is supported by the TE Connectivity dimming receptacle 2213362-1. The photocell and ballast are connected through this receptacle. This dimming receptacle supports ANSI standard dimmable photocells with 5 positions (3 power contacts and 2 dimming signal contacts). Its power contacts can handle voltages up to 480V AC/DC provided that the maximum current passing through it will not exceed 15A. The dimming contacts of this receptacle supports 0-10VDC dimming method with a maximum current of 0.10A

Automatic Light Switching System with Dimmer – [Link]

iHome – Intelligent Thermostat Project

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by jwozniak @ jwdevs.com :

The world of IoT for “Smart Home” is growing very fast. There are various areas of interests from security to automated animal care depicted for instance on this page.

I’ve tried to look at the things from the practical point of view. What would be interesting enough to be build as a project and at the same time have a real, quantitive value? It happens that I was always interested in limiting the energy consumption at home. One evening when talking to my wife and trying to get her opinion on my adventures into electronics she said that it would be great to have a heating already on before she gets home (and a cosy, warm place ready exactly when she enters). I guess she said it as a kind of a joke. To her surprise I got attracted by the idea. Hey, why not? With the current state of technology it is actually feasible. Maybe a bit challenging at first sight but still. So this is how it has started. Let’s build a intelligent thermostat that would be off when we are not at home and turning on when we come back! Great! Let’s see, maybe it will even improve the energy consumption…

iHome – Intelligent Thermostat Project – [Link]

Capacitance Meter

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by ThomasVDD @ instructables.com:

Capacitors are vital components in electronics, but sometimes they are broken, or the value printed on the cap has become unreadable. Because my multi-meter does not have a capacitance measurement, I decided to make one!

The principle of measuring capacitance is quite simple. The voltage of a capacitor charging through a resistor increases with time T. The time it takes to reach a certain voltage, is related to the values of the resistor and capacitor. In this project, we’ll use a 555 timer circuit as a monostable multivibrator. If that sounds like some dark magic to you, don’t worry, it’s quite straightforward. I’ll refer to the the Wikipedia page for the details, as we’ll focus on the things we really need: the schematic and formula. The time in which the capacitor C charges through the resistor R is given by: T = ln(3) x R x C = 1.1 RC. If we know the value of the resistor and the time, we can calculate the capacitance: C = T / 1.1R.

Capacitance Meter – [Link]