Monthly Archives: October 2010


Real-time clock and Temperature display on 16×8 LED Matrix

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Digital clocks and temperature meters are very popular projects. There are tons of such projects available on internet. This one is little bit different. This displays time and temperature both scrolling on a 16×8 LED matrix. PIC18F2550 is the brain of this project that controls the columns of the display through A6276 (a 16-bit serial input, constant current latched LED driver). The rows are controlled with a 74ACT164N (8-bit serial-in parallel-out shift register). The required current to drive the rows are provided by BC337 transistors. A DS1320 serves as the external real time clock, whereas the temperature measurement is performed

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USB Development Board for PIC18F4550

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This article shows how to make a low cost USB development board for PIC18F4550 similar to Microchip’s PICDEM USB FS board. The Microchip’s USB stack examples can be compiled and loaded directly without altering the code. Access to each of the 40 pins is provided through female headers so that the connections could be extended to a breadboard easily during prototyping. The board has got a LM7805 voltage regulator with a polarity protection. This board will be very helpful in prototyping PIC based USB projects.

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50 MHz range frequency counter using AT90S2313

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A wide range frequency meter is an useful tool for an electronics lab. This projects describes a frequency meter based on AT90S231 microcontroller that can measure input frequencies up to 50 MHz. The measured frequency is displayed on 6 digit multiplexed seven segment displays. It uses two external high-speed 8-bit counters (74HC590) in cascade to count the incoming pulses. Depending upon the input frequency, the counting interval for the external counter circuit is changed by the microcontroller for getting better accuracy. The firmware for AT90S231 is provided in C.

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PIC based shaking LED dice

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Electronics dice projects using push buttons are available all over the internet. This one is a little bit different. It is meant to provide the real feeling of shaking a dice by using a spring with weight and a wire. The two make and break contacts when shaken. The PIC16F688 microcontroller detects the contacts between the spring and the wire, and rolls the dice. After the spring motion stopped completely, the dice output number is displayed with glowing LEDs.

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Easy Data Logger with Virtual USB

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“V-USB is a software-only implementation of a low-speed USB device for Atmel’s AVR® microcontrollers, making it possible to build USB hardware with almost any AVR® microcontroller, not requiring any additional chip.” For further details on V-USB and licensing, visit http://www.obdev.at/products/vusb/index.html This is a data logger project that reads an analog signal, converts into digital number, and sends it to a host computer using Virtual USB. This is a good example application of V-USB. An 8-pin ATtiny45 microcontroller without an external crystal oscillator is used for this demonstration. The beauty of this project is the ATtiny45 presents itself as a USB

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