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PIC based RF monitoring system

If you need to monitor distant objects you probably would go with wireless transmission. This project simply demonstrates a standard setup of RF data transmission channel using cheap 433MHz or 315MHz modules. They are connected to PIC16F877 microcontroller using HT640 encoder on transmitter side and HT648 decoder on receiver side.
With encoder you don’t have to take care of formatting data packets. Decoder in its hand automatically encodes data from received packet. Microcontroller only has to read it and perform its own actions. In this particular example there are two sensor data transmitted – LM35 temperature and potentiometer value. Set up simply monitors continuously and updates parameter change.

Apple remote controller using custom Arduino shield

You know that all apple gadgets have their price. And probably most of that price goes in to design not whats inside. If you don’t care of design then check out this Apple remote shield for Arduino. It can be assembled in no time.
All you need to do is to solder 5 push buttons and couple IR LEDs. And of course make it fir into Arduino board. After you flash the chip you’ll be able to send simple commands to your Mac, iPod and hopefully Apple TV.

Breakout board for AVR Xmega

When you feel that Atmega microcontroller runs out of juices and you don’t want to change to different type of microcontrollers like ARM then you can go with Xmega. Problem is that Xmega chip packages are less friendly for hobbyists but still usable. Having this in mind Brendan assembled Xmega breakout board which simply fits in to breadboard for fast prototyping.
The board includes ATXMega32a4u microcontroller alongwith power supply, USB port and I/Os aligned to fit nicely in to the breadboard. His intent is to make it more friendly for newbies by adding Arduino support for it. As a reference he’s using the XmegaDuino project. There is still lots of work to be done but you can start building one for yourself as you know it takes some time.

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High resolution lightweight capacitance meter on PIC

 Many capacitance meters limits their resolution to 3 or 4 digits while this one reaches 7 digits. What does it mean? This means that you can measure capacitance more precisely especially when talking about very small capacitors in pF range. Device is built around PIC16F628 microcontroller which also provides its internal comparator for oscillator.
Using PIC’s internal comparator makes cap meter very lightweight on schematic. Whole magic happens in comparator circuit where tested cap along with known resistor generates a waveform. Comparator is set to capture high and low signal values at 1/3VDD and 2/3VDD while microcontroller timer counts waveform period. Knowing period it is easy to calculate capacitance value. Cap meter also has a zeroing and calibration functions that helps reaching better precision. 

16 pin PIC module ready for breadboard

Using various breadboard modules is a popular way of fast prototyping. If you have favorite microcontroller that you usually grab to start prototyping probably it is worth to build plug-able module that would save significant time of actual breadboarding.
embedded-lab have built a small PIC16 based PCB for prototyping. It can hold any 18-pin DIP PIC microcontroller which is clocked at 16MHz with ceramic resonator. There is also a mandatory ICSP programming header and reset button. All microcontroller pins are aligned so they fit nicely in to breadboard. In many projects there are commonly buttons and LEDs used so in this module one user push button and single LED is already included that can be used for any purpose. Besides there is a dual tact switch that allows disconnecting button and LED if not needed.

Voice activated home automation 

You may think that building home automation system is a tricky task. But in reality you can do this in less than day. jjshortcut shared his bedroom automation system that can be controlled with voice commands. His starting point was purchasing a Veear Easy speech recognition module. It can be interfaced via USART so this makes it ideal module for microcontroller project. For this he used Attiny2313 microcontroller assembled on a custom board.
in order to control devices he vent with RF controlled 230 sockets. By hocking microcontroller pins to remote buttons it is possible to send remote commands activated by voice only.

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Setting up an USB communication for PIC 18F4550

PIC 18F4550 microcontroller is equipped with USB peripheral that allows to get rid of USB-to-TTL level converter circuits like FT232RL. This saves board space and money. Anyway lots of gets scared of USB complexity and avoid using native USB. Well this is true unless your starting point is a working project template.

usb communication

Gaurav have put up a working project example that utilizes PIC’s USB as HID device that is automatically recognized and installed by most operating systems like MS Windows or Linux. His project allows controlling 16 I/O pins of microcontroller by clicking buttons on PC screen. This may be a good starting point for your next USB based project.

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PIC based candle simulator

Burning candle is relaxing and gives warm feeling. No romantic moment passes without a candle. João took a challenge to simulate candle light with a LED and small microcontroller.
The task isn’t so easy as it may look. Random flickering of LEDs won’t work here. First of all candle light is warm and waves slowly that gives a feeling of oscillating air around. This work is a second version of previous where he used single LED and MCU. This time he decided to go with two LEDs to get effect more close to candle. Program is based on PWM with random bit. Circuit isn’t hard to rebuild so be first to check out if this is close enough to candle light. Can you do better? 

PIC based LC meter remake
LC meter is a handy device. Probably any hobbyist can find C meter on their multimeter while L meter is rare feature on common devices. If you feel that you need compact and reliable LC meter then check this one. This is actually slight remake of Phil Rice original LC meter that was designed quite some time ago. But this circuit seems to be time proved and can serve as good reference for new one.
Among changes there is a Li-Ion battery that replaces 9V pack. So this needs a 5V voltage booster and charger circuitry to make it work. Mini USB connector were added to make charging easy. Also there were minor changes made to firmware where recalibration were fixed. Board was placed in to nice box and now looks really pro.

PC to micro-controller wireless data transmission using photo-diodes

While driving his car to pick up his wife Scott suddenly got an idea for a fun project to build. Inspired by the flashing of another vehicle’s emergency lights he planned to do an experiment on wireless data transfer between a microcontroller and his personal computer Using a pair of photodiodes, a couple of transistors and a few resistors to serve as the sensors for his microcontroller, Scott was able to read data from a strip of black and white lines. When the photodiode passes a black strip it reads 0 while 1 for a white strip – this is following the reflection principle.
At first, he was using digital inputs however he ran into a few problems since the intensity of reflected light could either give all 1s or all 0s – to fix this he used an analog to digital converter (ADC) channel and used a range comparison – example 200-255 will be 1 while 199 below is zero.

During test, Scott was able to read the entire black and white strips and have them displayed using java script.

Attiny13 solar tracker project

If you want to harvest solar energy efficiently you need to direct solar cells directly to sun. You can’t stand near and adjust solar panels by yourself. This is where solar tracker device comes handy. Cuningan is building solar power plant and have constructed simple solar tracker circuit based on Attiny13 micro controller.
He uses two light dependent resistors connected as voltage divide to single analog input. Ideally when both resistors get same amount of sunlight this means that solar panels are oriented optimally. And if one of resistors start getting less sun in time; micro-controller moves panel with motor connected through H-Bridge. Sensitivity threshold can be adjusted with potentiometer so it would react only when significant change of light is detected.

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Vowel Recognition Using an Mega644 

For their final project, a group of students at cornell university decited to make a smart voice decoder for vowels, this basically acquires samples of your voice, do the wave math and determines which vowels are being spoken.

The input is captured using a microphone through an amplifier circuit. Voice data is analyzed in real time (ill say it again REAL TIME) using a Mega644 micro-controller. It has both hardware and soft ware interfaces that would trigger the analysis the user could use a button (yellow) or could enter a command in PuTTY.

As an application of their methods they also built a simple voice password system. Where the only way to gain access (unlock) is to correctly utter a sequence of vowels at the correct order. I really like this project specially that it touches the topics of  Fast Walsh Transform, sampling theorems and human speech analysis. We are waiting for the version 2 of this to come out, come on people add the consonants ide like to try “Open Sesame” on our house!

A Tree Climber Using an Arduino

There are several implementations of tree climbing robots out there (still climbing trees?)
Technochiken – a new Arduino fan wants to test his newly acquired skills in programming microcontrollers……..(the dots represent the time he spent searching on the net) He finally decide to build a tree climbing robot using the Arduino as the the main controller that would facilitate the climbing motion of the robot. He starter the build process with a sketch of the mechanical parts – its better to have a plan to avoid wasting materials.

The robot is mainly composed of aluminum – the frame, the claws (the legs) and it has a central shaft that it used to create the climbing displacement. The claws and the central shaft is powered by DC motors which in turn are driven through an L298 H-Bridge Motor Driver. One unique thing about this climber is the fact that it senses the gripping of the tree by determining the speed of the motors – the motor’s speed goes down when the gripping action touches the tree – talk about neatly designed robots.

Gloves with MIDI output

We’ve seen lots of MIDI devices, but usually there is a PC program of keyboard that allows synthesize sound. In this student project MIDI is generated by taping fingers. This is achieved with specially designed gloves where piezo sensors are attached to fingertips. Sensors are read by Atmega644 microcontroller.


They used a MATLAB client to map notes to different sensors. So there were two separate USART channels used – one for mapping tones and second for sending MIDI messages. Because flex piezo sensors allow sensing tap force this information is also passed allowing to represent the note intensity.

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Arduino based Bluetooth watch

Electronics hobbyists probably would love to have watch that could do lots of things regular wristwatch couldn’t handle. Probably the only way to solve this problem is to make such watch by yourself. Ahmet thought so and started open source Bluetooth watch project.

It is based on Arduino Mini Pro. He’s chosen Bluesmirf GOLD for Bluetooth communications and of course large LCD from Nokia 6610. Watch looks quite big on a wrist and still lacks of enclosure, but probably most important thing – what magic can it do. Currently it is able to talk to Nokia N900 and display missed calls, emails. Of course there is a nice graphical clock on top of this. Seems that project is still under heavy development. Ahmed is working on medial player support so he could remotely control music played.

Plotting Heartbeats with a Propeller

This is kinda a dangerous project – for one the circuit used to sense cardio activity will include a path that crosses the human heart – thus if a shock would occur (now you know what will happen) you might get hurt. Thus as a warning don’t use high voltage sources (including step down power supplies) and you may use the information in this project at your own risk!

The concept behind this project is fairly simple – when your heart beats it produces a small potential difference (Voltage) across different points in the human body. This potential difference is sensed using three electrodes each electrode will go to certain parts of the body on on each thumb and the third one could be on one of your feet. The electrodes is connected to inputs of three amplifiers the two from the thumbs is connected to an in amp while the third one is connected to two other amplifiers (one configured as an integrator while the other configured as a x100 inverter) to be used as a common mode voltage – the third one is for common mode rejection. the output of the amplifier stage is then fed into an ADC input of the propeller which samples the signals.