Dilshan R Jayakody’s Web Log

This is a simple sensor kit to drive 8 active or passive sensors and log its data into a remote Android application. This system also has an option to activate an external device(s) based on the specified threshold of sensor data. This sensor controller is mainly built around the Raspberry Pi Model 3 B+ and PIC16F877A MCU. PIC16F877A MCU is used to interface/select sensors and it's built-in 10bit multi-channel ADC is used to capture the analog signals from sensors. During the prototype stage following sensors are tested with this system: LM35 precision temperature sensor MQ7 Carbon Monoxide gas sensor Electret Microphone NSL-19M51 LDR HC-SR501 PIR sensor A3144 Hall effect sensor Apart from the above list this system can use to drive and capture most of the other analog/digital sensor signals such as current sensors, pressure sensors, chemical sensors, humidity sensors, etc. In this system, Android monitoring application is designed to connect with the sen...

This article describe the LMD18245 and PIC16F877A base 16 step bipolar stepper motor driver which is design to work with 12V 18 º bipolar stepper motors. In this design we use pair of LMD18245 DMOS full bridge motor drivers to control 2 phases of the stepper motor and PIC16F877A MCU is used as controller. We test this driver with several stepper motors (including 1.8 º - 12V stepper motors) and all of them provide excellent smooth output with this driver. The supplied firmware of this driver is design for 16 micro-steps but it can be easily change to full-step, half-step, 8, 32 or 40 micro-steps. In this given design LMD18245 current sense resistor is calculated for 200mA and it can be extend to 3A by changing the value of R2 and R4 resistors. For more information refer the LMD18245 datasheet . This project is released as open hardware project. Firmware of this project is released under the terms of MIT License and schematic is released under the terms of Creative Commons ...

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 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...

In this article we implement virtual (computer simulation base) microcontroller driven programmable timer using Proteus VSM. This proposed system is design using Microchip PIC16F877A – 8bit microcontroller and its system software is developed using MikroC PRO 3.2 for PIC. Most of the components in this proposed design are based on Proteus VSM - simulation models and we assign standard component names to them to assist in actual prototyping. In this simulation we use PIC16F877A as main system controller and 4 row monochrome LCD display unit with HD44780 compliant controller (in 4bit mode). This proposed simulation model is design to work with +5V supply voltage, but it can also operate using battery power (3 × 1.5V). When implementing this system for the real-life use, it is highly recommended to integrate battery backup facility to this system. It helps to drive this system continuously with minimum amount of disturbances. According to the supplied source code, end user may be a...