Wrist-Watch for Nerds

This wristwatch, made by Elia, is a binary-based wrist watch i.e. displays time in binary digits and is small in size. The yellow-color LED’s for the digits perfectly suits the watch and also is compatible with the OSHPark PCB, which is a custom PCB-board manufacturer. Another interesting fact about the watch is the strap which is a paracord bracelet along with a buckle. The steps to make the buckle are easily available on the internet. The watch is powered by the PIC microcontroller which comes with an SSOP package. These watches are designed for So Nerdy people who enjoy tech and want to be around such gadgets. Along with the PIC, it also has an on-board ‘real-time clock’. Moreover, it also features a sleep mode in which there is no display and consumes only 150uW of power. There can be additional power saving by pulling the remaining pins to either VCC or GND. However, this functionality is not yet available in the current PCB. Overall, the watch is really good and a must-try for those people who have just started… Continue reading

Low cost home made plotter project

Probably many of you are thinking about how cool is to have CNC plotter or 3D printer. There kits and ready printers available for reasonable price. But still they are pricy for hobby use. But nothing is lost you like to build stuff. Hobbyprojects.com posted his progress in building plotter where he wanted things to be cheap and simple. He’s build all part separately by finding simplest and cheapest solution to rising problems. Some of his parts came from Epson printer. He also purchased used stepper motors from local junk store. The electronics part he built around PIC16F877 microcontroller. He built his own motor driver circuit out of discrete components, but it seems that results aren’t as good as it would be with specialized chips like Allegro A3984. Connection to PC was implemented via optocouplers. Several LEDs indicate each motor activity. Continue reading

Microcontroller driven resistor decade box

Usually resistor decade boxes are mechanical – a rotary switch comutates resistors while turning it around. But if you decide to build one, you may face problem by selecting this switch. They seems to be quite expensive and quite old fashioned. Stynus has been planing to build one of those, but mechanical switching handle didn’t look very attractive, so he decided to switch resistors electronically through microcontroller. He ended up by building three PCBs where one is a control board carrying LCD, PIC 16F648A microcontroller, rotary encoder and push button. Other two boards are resistor boards – one for high value resistors and another for low value. Each resistor board caries 16 small relays that are controlled through shift registers. Then only annoying thing with electronically controlled resistor box is that you need a power supply for it where mechanical boxes are passive. But seeing resistor value on screen probably pays off. Continue reading

Remote controller uses NEC protocol

Today almost anything has remote control ability, If few years ago mostly we could control TV, stereo, so today it is normal to turn on lights, close blinds, adjust heater and many other things using remote. But there will always be something what requires direct control. But if you like to improve things your way, why not making you life easier with another remote. Gaurav has build a remote control relay board some time ago. But it seems that it needed a remote controller itself. So he started another project where he paired this board with DIY remote. Remote controller works with NEC encoded commands. This standard is described pretty well in project page. The schematic is really simple – PIC12F615 microcontroller which drives IR LED through transistor key. Five push buttons are connected directly to microcontroller with internal pull-up resistors enabled (just one need external resistor). Remote controller is powered with 3V cell coin battery and seems to be last long enough because microcontroller most of time spends in sleep mode. Continue reading

Microcontroller Based Digital Capacitance Meter

Have you guys ever wondered how does capacitance meters work? This project walks you through the process of building your own microcontroller based capacitance meter. It uses a PIC16F628A – this was choosen because of its simplicity and it has built in analog comparators and timer modules. Theory behind the operation of this capmeter (and most capmeters) revolves around the charging time constant – the amount of time it takes for the voltage of a capacitor to reach a certain level (in this project Vin/2) from 0V (no charge at all). This capacitance meter is equipped with a 2×16 liquid crystal display (LCD) that is hooked up into the PIC16F628A’s port B. Regulated power is supplied through a 78l05 voltage regulator (this is added to avoid corrupting the result due to unstable supplies) . Measurement is initiated using a momentary switch that is hooked into RB0 – Just press START and start measuring! Continue reading

Using PIC to program AVR

PIC based AVR programmer

It is common norm that AVR programmers are based on AVR microcontroller. But practically there is no difference which MCU is forced to pump the firmware – the only thing that matters is programmer firmware. But if you don’t feel comfortable with this idea, check out jeromir’s project where he ported STK500 firmware from tuxgraphics to PIC16F1825 microcontroller. He’s not taking the credit for all the hard work as he only cleaned code a bit and wrote new hardware layer. It to only one evening to accomplish. The programmer is assembled on through hole prototyping board with MAX3232 interface chip. As jaromir says, this wasn’t intent to build a tool, rather this was a fun project to marry two most fighting MCU sides. But if you feel this is useful, no problem to add FT232RL instead of MAX3232 and make it an USB programmer which has no problem to work with older AVRstudio or AVRDude. Continue reading