Arduino based high altitude balloon data logger

One of the more interesting experiments you can do above surface of earth is fly balloons in to stratosphere. Fun thing is that whole experiment isn’t very expensive and can give tons of fun. Probably most expensive thing here is balloon itself. The other parts can be used as you desire. Spaceshark have shared his experiment and build details on his instructable. He used Arduino Uno for logging various basic sensors detecting latitude, longitude, altitude, wind speed. He wanted to keep things simple and self contained, because at heights above 60000 ft some sensors start failing, e.g. GPS. Batteries are also another issue due to cold air above. He used authentic Arduino to make sure it works bellow -40 degrees Celsius. Fake ones can fail even at 0 degrees. Same applies to other modules. Better use original and tested parts. Apart Arduino, he used SD data logger to record all sensor data in portable media. The only thing is missing here – balloon tracking. It can get to heights of 100000 feet and probably will get out of sight. Wind… Continue reading

Fully featured Arduino based code lock

If you have a door lock that is activated with solenoid, then probably you would like to have a keyless access. This can be done easily with Arduino, keypad, LCD and relay which activates lock mechanism. Praveen has shared a second version of code lock he built. In previous version he simplified too many things like, no LCD, hard coded password. This time he wanted to make things better and included all missing parts. During initialization, user is prompted to enter a password which also can be changed later. Using LCD made it much easier to enter passwords navigate menu and debug program itself. Continue reading

Simple Arduino voltmeter for starters

Building a DC voltmeter with Arduino is really a matter of seconds. But for those who is learning microcontrollers and want to build something working this is a great project. Here you have to deal with several areas of electronics. First of all reading analog signal. As voltage cones in directly to analog pin, the range is limited to 5V. Next thing is driving three 7-segment Led display. It is common anode type where anodes of each digit is driven with transistor key. Program code is also easy to follow and easy to modify if needed. Even if it looks simple project, it can be useful in many areas like checking battery voltage, or probing other things where voltage ranges from 0 to 5V. Continue reading

An arduino based Wifi Bodyscale

For all ya geeky weight watchers out there! Here’s a project that will measure your body weight, connects through wifi and records each result onto google docs – neat isn’t it? The project was built out of an Arduino Uno, a Wifi shield, a Velleman scale (that was ripped open for this project) and an LCD shield to display how much you weight. The Velleman’s load cells are hooked up into the arduino uno’s analog to digital converters through a INA125  chip that is specifically build for load cell  applications like weighting scales. The INA125 sources the precision voltage that is fed into the load cell which acts like a resistor bridge, the differential result would be in a few milivolts thus the INA125  also has an amplifier that amplifies the signals 500 times so that it can be detected by the Arduino Uno’s analog to digital converter. The uno then builds up a packed data using the APP_WISERVER  library to connect with wifi and then google docs for the recording of the weight data. There are some critical steps that need to be… Continue reading

Programming trick makes it possible to reach 3MSPS on Arduino logic analyzer

You can find tons of Arduino based measurements tools including logic analyzers. Logic analyzer is pretty easy to build as it requires only to detect high and low signal levels. The other problem is to to capture fast signals. Signal sampling heavily depends on firmware optimization and clock speed. Anyway Bob Davis has managed to reach nice goal – 3 Million samples per second. He noticed that using loop in sampling process reduces sampling time more than twice. So instead of cycling through samples he typed each line that stores individual samples. Of course it takes code space and time to do this. But 3MSPS pays off. And this is not only single channel, but 6. Results are displayed on graphical LCD where all 6 channels are displayed. In his demo he uses 74LS390 decade counter to scale down 10MHz signal in to six to be tested. Continue reading

Arduino makes new turn with Uno and Mega2560

We have some good news in Arduino side. They came up with two new and different Arduino boards – Arduino Uno and Mega2560. These new Arduino boards are somewhat different from those that we are used to see. And probably biggest changes are different approach in converting USB to serial and different bootloader.  First of all USB chip… They decided to get rid of FTDI chip (FT232RL) and used Atmega8u2 chip instead that gives even more power when dealing with USB. By default chip is configured to work as USB to serial converter, but there is an option to turn Arduino into different USB device like mouse, keyboard or MIDI device. So these are good news. Bad news are that using atmega8u2 forces to have your own unique product ID and vendor ID – these cost money, while FTDi chips came with their IDs. But this is more important if you want to build your own board – many of them. Anyway there is always an option to get back to FTDI as bootloader doesn’t care how data reaches it.… Continue reading