Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Simple PIC based timer with LCD

Programmable timers are used in many areas. You can set timer to turn on/off light after some time, turn off oven, control water sprinkler and do other time dependent switching. You can buy such timer for cheap – some of them even plugs in directly to AC outlet. But if you like to have things in control and be able to add additional features, then you can build a simple timer with small microcontroller. Hristo has built a programmable timer on PIC16F628A microcontroller. He intended this timer to be used in hos UV light exposure box. But by adding a relay, it can be used for anything. Timer can be set and run with three switches where couple of them are for setting minutes and seconds. LCD indicates timer running state and is used to navigate menu while setting time. Timer also has a calibration jumper where timer can be adjusted to run more accurate. Once timer runs out timer turns switch off and then sounds buzzer alarm. Really simple and useful circuit. Continue reading

Microcontroller based Time/Date/ Temperature keeper

Time is gold – so they say. Well people always keeps track of time and often people keeps forgetting about the time then ending up late for work, school and sometimes a date – what a disaster! To help those geeks out there who keeps on forgetting time bogdi put together this nifty contraption that keeps date and time while also having the capability of measuring temperature. A PIC16F628 or PIC16F84 microcontroller is used to keep the date and time information while also driving four seven segment displays and a DS1631 temperature sensor is used to gather temperature data from the surroundings.  The DS1632 temperature sensor is wired out away from the main board so that it could also be used to sense temperature from a specific spot a little further from the controller. It’s the geeky way of telling time! Continue reading

555 Timer reduces number of I/O pins in Keypad Interfacing

Keypads are very common input devices in  embedded systems. The most common method of interfacing a keypad involves scanning of rows and columns to determine which key has been pressed. The multiple keys in a keypad are arranged in the form of a matrix to reduce the number of interface pins but that still requires quite a bit of I/O resources which may not be affordable by mid-range microcontrollers. This article is about a keypad interfacing technique that requires only two connections to interface with a microcontroller. It uses a 555 timer IC configured as an astable multivibrator where the frequency of oscillation is varied with the pressed key. The technique has been demonstrated with a PIC16F628A microcontroller that couts the 555 output pulses through the Timer0 module for an interval of 100 ms. The information about the pressed key is derived from the number of times the timer module overflows during the interval. Continue reading

Digital clock in power supply box

Probably everyone knows how to build a digital clock. Take a simple microcontroller like PIC16F628A and connect a bunch of LEDs to pins. The rest is up to software. Next task is what enclosure to use. If you don’t want to to build one, there are many options to use something ready. Like in this project Victor used an old enclose from broken laptop power supply. Made holes for LEDs and buttons and got pretty good looking digital clock. Continue reading