A person’s inquisitiveness and curiosity can do wonders. It can open a realm of ideas and imaginations never thought before and create something worthwhile.  When I was a child I used to read lot of electronic articles and magazines regularly. I’ve seen a lot of interesting circuits and tried as many of them as possible at that time. Whenever a new circuit catches my attention I can’t resist myself trying it out. Every time I bought a new general purpose PCB and the required components listed with the circuit diagram and spent a lot of time soldering the components in the general purpose board. I used to implement the developed board for its practical purpose but it won’t last too long in its place and eventually end up in my small junk yard. Earlier, I couldn’t afford the cost of all these hardware and now with the passing years I have a large collection of useless circuit boards with costly components soldered into it.

SPI has earned a solid role in embedded systems whether it is system on chip processors, both with higher end 32-bit processors such as those using ARM, MIC  or Power PC and with other microcontrollers such as the AVR, PIC etc. These chips usually include SPI controllers capable of running in either master or slave mode. In-system programmable AVR controllers can be programmed using an SPI interface.Chip or FPGA based designs sometimes use SPI to communicate. So, SPI is a common technology used nowadays for communication with peripheral devices where we want to transfer data speedily and with in real time constraints. There are many serial interfaces right from Morse code telegraphy, RS232, USB, Fire wire, Ethernet and many more. Each serial interface offers advantages or disadvantages for many designs,depending on criteria such as needed data rate, space availability, and noise considerations. 

An uninterruptible power source, UPS or battery/flywheel backup, is an electrical apparatus that provides emergency power to a load when the input power  source, typically mains power, fails. A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide near-instantaneous protection from input power interruptions, by supplying energy stored in batteries or a flywheel. The on-battery runtime of most uninterruptible power sources is relatively short (only a few minutes) but sufficient to start a standby power source or properly shut down the protected equipment.

There are different types of UPS such as On line UPS, OFF line UPS and  a Line interactive UPS.This project details in creating an offline project with PIC microcontroller. Off Line UPS the load is connected directly to the mains when main supply is available and it is not too high or not to low. Continue reading to find out how PIC microcontroller is utilized and how the project is put to work.

Here is very useful application that controls the number of rotation of 12 V DC gear motor with very low RPM (1,2,3,5 or 10 etc).You may find lots of  applications of this project in robotics, CNC machines, manufacturing industries etc. Here are some of the examples In any PCB cutting or PVC pipe cutting CNC machine (or any other automatic cutting machine) first the linear dimensions are calibrated in terms of number of rotations (e.g. 5 rotations = 1 CM), then by adjusting the number of rotations as per required dimension one can easily move the cutting tool to that distance (e.g. for 1 meter 500 rotations).

 In robotic arm application, if the arm has to move to a specific position then first its movement can be calibrated in terms of number of rotations of motor. Afterwards once we program and set the number of rotations for a button, the arm will always move to that position when that button is pressed.