This project is for those who always wanted to make their own stopwatch. It’s built using a combination of eight seven segment displays multiplexed together and hence can be control by a fewer number of pins. It’s capable of timing minutes seconds, and even 1/10 of a second. The entire project revolves around a chipKIT Uno32 board. Along with the capability to time, it also has start and stop buttons just like a traditional stop watch. This project uses the millis() function for time keeping. The millis() is a built-in function in Arduino, and so in MPIDE, that returns the number of milliseconds elapsed.
The LedControl library is used in this project to interface the MAX7219-based seven segment LED display with the chipKIT Uno32 board. The stopwatch is started and stopped by pressing the push switch attached to INT0 (pin 38) pin. The INT0 trigger mode is defined as FALLING, which means the interrupt routine is called when the INT0 pin goes from high to low. For those interested in the project the complete schematics along with all parts number and the code with necessary library are available to download from the project website.
Just like me, there would be people who are interested in monitoring temperature every now and then. Well, then this project is just made for you. The project is all about building a temperature and humidity sensor which will log all the data to the pc from time to time basis. It uses a DHT11 sensor which is an integrated sensor for both temperature and humidity and has a calibrated-digital output. It works on SPI protocol which is hard to integrate with any 8-bit controller. Another advantage of the project is that it doesn’t require wires as all the components are ‘plug-and use’ type.
In this project, four pins of the DHT11 sensor is directly inserted into four I/O pins (7, 6, 5, and 4) of the Uno32 board. Writing firmware is easier with the use of the DHT11 library available for Arduino or chipKIT platform. The DHT11 library for Arduino was originally written by George Hadjikyriacou and was later modified by other people. On PC’s side, the open source programming language Processing is used to develop a graphical application to display the received temperature and humidity information. Processing is an open-source software development environment designed for simplifying the process of creating digital images, animations and interactive graphical applications.
ChipKIT is great development board with Arduino spirit. Just it uses 32-bit PIC microcontroller and has more flash and RAM memory. If have one here is a nice project based on ChipKIT UNO32. The only additional component to this project is DHT11 temperature and humidity sensor. It can be plugged directly in to ChipKIT header and be read.
ChipKIT simply reads data from sensor and pushes it to serial interface. Not so much of performance requirements. The fun part is on PC side. The GUI is written in processing where nice window indicates current temperature in Celsius and Fahrenheit and relative humidity %. When Start Log button is pressed it starts logging these values along with time stamps. Great project for learning and fast use.
ChipKIT UNO32 is a great substitution to Arduino boards. One advantage is that it’s 32-bit microcontroller and is much faster than AVR based Arduino. Programming experience is pretty same as it’s using same Arduino IDE environment and same programming style. SXRguyinMA developed shield for ChipKIT that is equipped with 12 ports for temperature sensors. It also has a header for standard alphanumeric LCD display.
Shield accepts standard 10k thermistor sensors. Reading can be viewed on LCD. This is perfect solution for monitoring temperatures of multiple objects. Could be house heating monitoring, beer brewery. And surely you can always use less than 12 sensors. Project is Open hardware so you can grab and build one.