Dilshan R Jayakody’s Web Log

This is a real-time clock based automatic LED lamp which we originally designed to use as a night light. This lamp can be programmed to turn on and off at the specific time of the day. For example, it can program to turn on at 6 PM on each day and to turn off at 4 AM the next day. The core component of this project is PIC16F883 MCU and its firmware is developed using MikroC Pro for PIC . We select this MCU because of its 7 KB flash memory, I 2 C, UART, E 2 PROM and built-in 8-bit and 16-bit timers. In this system, we use DS1307 RTC because of its availability in the market and lower external component count. A prototype version of RTC Lamp This lamp is designed to work with commonly available 7W LED panels. In our prototype design, we use 7W 24V warm-white LED module to test this system. To drive other LED modules change the value of the R5 resistor of the current limiter circuit. This system is designed to program using the RS232 serial port. A user can modify system time,...

This is PIC16F73 base digital data capture unit with optional EMF reader. This data capture utility is design to work with most of the analog sensor inputs and by default, it is equipped with the EMF reader module. This unit use PIC16F73's internal 8bit ADC to capture the analog signals. EMF reader unit in this schematic is useful to detect variations of EM field in the environment and it is mainly built around uA741 operational amplifier and 12mH detector coil . Normally EMF meters are used to trace electric wires, find hidden transmitters, and diagnose electric wiring problems ( and to find ghosts too ☻ ). This digital data capture unit can operate in 2 modes. In the first mode, it directly converts an analog signal into digital data and transferred to the host via a serial interface. In second mode it displays captured signal in 5 LED bar graph either slow or high-speed capture modes. This unit is designed to work with 5V 500mA power source and to get optional EMF reading...

This is demonstration project to control servo motor movement using physical marker and normal video camera. In this project video camera capture the movements of marker and calculate rotation angle based on that. This calculated rotation angle is feed to the servo through small MCU based interfacing unit. In this project video processing and tracking is performed using ARToolkit and controlling of servo is carried out using PIC16F628A microcontroller. RS232 interface is use to communicate between PC and microcontroller. Interfaces in optical servo controlling system This application detects movement of marker on Z axis (yaw) and transforms it into another numerical scale to manipulate the servo motor. Processing application is written using Visual C++ and configured to work on Windows operating system(s). The marker used for this application is needed to be a " square with some symbol " and user can train this system for any compatible marker. As per our tests, st...

This post is about simple Atmega325 development board which I was designed and build to test some large AVR systems. This development board contains ATmega325 MCU and MAX232 base RS232 driver/receiver unit. Thanks to SMD packages and components dimensions of this board get limited to 85mm × 62mm. This development board requires 5V external power supply and all its external circuitries (RS232 driver and hardware CPU reset) can be enable/disable through on-board jumpers. ATmega325 Development Board PCB design of this development board supports only for ATmega325 - TQFP64 package and MAX232 - SO16L package. This ATmega325 Development Board is release as an open hardware project and all its design files are available to download at google drive .

This is an easy to construct precision electronic event logger and using this we may be able to measure time differences in two events in range between 0.02 seconds to 6.8 seconds. This system is mainly design around PIC16F73 microcontroller and 4040 binary ripple counters. The main counter clock (reference counter) is oscillated around 2MHz. Most of the counter related components of this system are based on CMOS family of ICs. If you need more precious lower limit it is recommended to replace all these CMOS family of ICs with TTL equivalents (e.g: 4027 by 74HS73 with slight changes and 4040 by 74HC4040). The clock frequency of the existing counter can also increase up to 6.0MHz. The counter gets activate and deactivate in positive edge of the input signal. Thanks to the wider operating voltage of the CMOS ICs this counter may be able to handle +5V to +15V of input signal. At the end of the counter session system release total tick count to the RS232 interface and it can receive t...

This is an example application for our " Extend PIC Microcontroller‘s RAM by without using EMI " blog post. In this system PIC16F887 microcontroller is interface with four units of UM61512AK – 64K × 8 CMOS SRAMs. Monitoring signal is supplied to the MCU through “ PORT A ” and all the communications are performing through RS232 interface. In my previous post most of the readers ask me about pure C language routine(s) for memory access. To fulfill that request I rewrite both memory read and write operations using C programming language. Compared with the previous Assembly language routines, only performance glitch in this implementation is 16bit address decoding part (which consume some CPU cycles than assembly language implementation) With this given firmware user can operate this system by without installing any driver software in the host side. All the data capturing and reporting operating are done by MCU itself. Originally I design this data logger to do some photo...

Virtually all PIC microcontrollers have some banking mechanism to extend addressing to additional memory space. But this external data memory is not directly addressable (except in some high versions of PIC18 devices, which include PIC18F8520, PIC18F6620, etc.). In this post we describe easy to implement external memory interface for PIC microcontrollers. Theoretically most of the PIC microcontrollers can use this setup to extend its RAM space. At the prototyping stage we test this system with PIC16F877, PIC16F887, PIC18F4550 and PIC18F4620 microcontrollers. With current setup user may be able to address RAM space up to 192KB. But this can be extended up to 448KB by adding more SRAM modules to the system. In this given schematic we use W24512 – 64K x 8 CMOS SRAMs as a memory modules. 74HC373 latch is used as 8bit to 16bit address extender and 74HC138 demultiplexer is used as memory bank selector. All the files (including source codes, EAGLE schematic files, etc.) of this syste...

This is another configurable PIC microcontroller development board with E 2 PROM base storage and RS232 interface. Purpose of this development board is to emulate simple computation platform with storage, processing unit and control terminal. This development board contain LM2576-ADJ base 3A switching voltage regulator (with external power terminals), E 2 PROM base storage (AT24C04) with 512words × 8bit space and standard RS232 serial interface. All the peripherals of this development board can be isolated using onboard jumpers which include crystal oscillator, MCU reset line, E 2 PROM I 2 C interface and UART interface. This development board supports most of the 40pin 5V PIC microcontrollers which include PIC18F4550, PIC18F452, PIC18F4620, PIC16F877, PIC16F887, etc. Schematic diagram of this development board is available in Circuitbee with Creative Commons Attribution-ShareAlike 3.0 license.

In this project we develop easy to build Microchip PIC development board for widerange of PIC Microcontrollers (which include 40pin Microchip PIC16 and PIC18 devices). This development board contain only the switching regulator (to generate +5V DC from the input power source) and RS232 serial port interface. The switching regulator of this development board may support input voltage of +8V to +25V DC. RS232 Serial interface of this development board is based on Maxim's MAX232 driver/receiver IC. This given design have 6 two-way jumpers to select crytal osciliator, MCLR and RS232 Tx/Rx terminals. While at the protyping stages we test this board successfully with PIC16F887, PIC16F877/A, PIC18F452, PIC18F4550 and PIC18F4620 MCUs. Diamensions of this PIC Development Board is 110×85mm. Schematic, PCB design and some of the related documents of this project are available to download at google drive .

In this post we introduce easy to build, full featured PIC16F877A/PIC16F887 microcontroller development board. This development board contains following core features: RS232 interface PS/2 host interface Battery backup - Real Time Clock with I2C interface Highly precision 1-wire thermometer interface 4 Digit Seven Segment Display module HD44780 compliant LCD module 4×4 Keyboard 4 button onboard joystick 8×2 LED driver 8bit peripheral driver interface 8bit Digital to Analog converter module 36kHz Photo module for Infrared base inputs Wide supply voltage range from 12V – 40V To reduce the form-factor we design this system in a double sided PCB. When constructing this project make sure to use exact component values for PSU module (especially for L1, R1 and R2). When constructing the circuit do not connect R4 and R5 wires to the PCB. Both these wire links are providing to isolate the PSU from main board. After constructing the circuit power on the PSU and check the v...

In this project we design low cost high performance programmable home security system using few LDR’s as an input sensors. When above sensor(s) get triggered system may dial the user specified phone number (using build-in DTMF generator) and activate the high power audio alarm and lights. All the parameters of DTMF generator, audio alarm and light interface are programmed through the RS232 serial interface. Current firmware of this system presents interactive control system through the RS232 interface. This control system consist with the menu driven configuration options, self tests, system report generators, etc. This system also contain 5W (with 4Ω speaker) audio alarm with three selectable tone configurations, which include Police siren, Fire engine siren and Ambulance siren. This system uses a Microchip’s PIC16F877A as a main controller, LM339 as sensor interface, UM3561 as a tone generator and μPC2002 as a speaker driver (audio amplifier). LM7805, LM7812 and LM317 voltage...