Arduino based MPPT solar charger shield

When you are harvesting solar or wind energy, you want to take most of it. For this you need efficient power converter which would take raw energy and convert it to proper voltage level for charging your batteries or powering electronics. Soldernerd have build an Arduino shield dedicated for charging lead acid battery. He used a solar panel with voltage output around 17V which had to be converted to 14V for lead battery. This obviously required step down (buck) DC to DC converter which takes 17V – 18V from solar panel and converts it to 12V – 14V as efficient as possible. Microcontroller takes care of generating PWM signal which automatically adjusts to maintain output voltage level. Charger is capable to protect battery from overcharging when voltage of battery reaches 14V. Charger is capable to drive 30W power to the battery. Continue reading

Nice list of Arduino shields

Rui Santos have compiled a list of useful Arduino shields. This is great source if you are looking for ideas for your next project or simply want to try something new. He describes each shield along with eBay link where to purchase. He posts only 25 shields while there are hundreds of them. If you will dig deeper, probably you’ll find a shield for any purpose you may think. Continue reading

Biomedical engineering at your home – DIY PPG sensor

Photoplethysmography (PPG) sometimes called pulse oximetry is on of the easiest ways to get heart rate information. With a little more analyze and signal processing it is possible to extract even more information related to your heart condition like arrhythmia. But first lets focus on how to acquire PPG signals with the things you might have lying around. SteveQuinn have built a PPG device around Arduino Mega2560, 128×160 TFT LCD, and several passives. The measuring of PPG lies on blood perfusion to the dermis and subcutaneous tissue of the skin. Every cardiac cycle pumps blood to peripheral organs and this flow change can be measured with simple optical method – LED and photo diode. There are two ways of measuring PPG waveform – transmissive and reflective. Transmissive method seems to give better results this is why it was selected for this project. He built a simple finger clamp out of coat hanger where he fixed LED and photo diode. There are many small things to take care of, because signals are very small and susceptible to noise. For instance LED… Continue reading

Arduino based GPS data logger to SD card

You can use GPS data for many interesting projects and experiments. By analyzing logged data you can track the movement of the object, analyze you hiking route, RC plane model, weather baloon and other crazy stuff. Building such logger isn’t very complex task as it involves only standard modules and practically no soldering needs to be done. Almost all standard GPS modules support so called NMEA0183 data format – a short message which contains all data including position and time stamps. Once connected, GPS module automatically sends this data via serial interface. Arduino simply needs to capture it and store data to memory like SD card. In this project, data is stored in FAT32 (or FAT16) formatted SD card. Arduino accesses SD card through SD card V4.0 shield. This is simple a barebones for developing project further to fit your specific needs. Continue reading

Laser engraver controlled by Arduino

Laser engraving can be a great way of adding ornaments, labels and other graphics on wooden surfaces. Nobody wants to buy industrial engraver for hobby projects, and if you follow MichielD99 instructable, you can build one by yourself. He used 1.8W 445nm laser module which is enough to burn engravings on wooden surface, but not close to laser cutting. He build his own parts out of MDF boards. Electronics part consist of Arduino UNO which drives two stepper motors by using motor driver boards. Arduino by using pen source grbl-mster software library accepts Gcodes to drive the laser position. Images can be generated with software like inkscape which supports the extensions provided by himself. He tried to keep make all system free and accessible for everyone , so he used all open source software to reach the goal. Continue reading

Improving 3D graphics for Arduino LCD shield

Arduino Uno features Atmega328 microntroller with 2KB of RAM. When you start working with graphics LCD, memory melts down immediately. One of the common GLCD shields for Arduino is Adafruit’s LCD shield which features 320×240 color graphical LCD driven by ILI9341 driver IC. There is a ready made library that allows drawing graphics with few lines of code. This is OK for simple drawings and menus, but when you start working with some motion and animation flickering and tearing occur. This is due to limited memory on Arudino. Simply speaking there is no space to render whole frame off-screen. 340X240 frame would require 500KB. M Rule starting looking for more optimal ways of displaying and updating graphics on screen that would minimize these effects and make graphics update smoother. He started tweaking Adafruit’s library with custom solutions that makes rendering stages less visible to human eye. One of the ways is to render frames on top of each other first and then remove unnecessary pixels. This works great with mesh graphics, but 3D surfaces there is also a Z buffering… Continue reading