Dilshan R Jayakody’s Web Log

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 a high current 5V bench power supply for digital (and analog) electronic experiments. This power supply is based around National Semiconductor's LM338K positive voltage regulator. Virtually this is an indestructible power supply unit with short-circuit protection and thermal overload protection. 5V 5A Power Supply in ATX Power Supply Casing In our prototype we assemble entire power supply (including step-down transformer) in an ATX power supply casing. When assembling this power supply take extra care about wirings and mountings. LM338K need proper heat-sink and make sure to mount it closer to the main PCB. While assembling makes sure that all the wirings are in correct order. Improper wiring and/or shot-circuits may leads to critical component failures (including voltage regulator IC and step-down transformer ).  Schematic diagram of this power supply unit is available to download at google drive

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 an AT89S2051 base 8bit bus monitoring utility. This module indicates bus values using hexadecimal numbering format and notify value changes by the beep. This utility is design to work with any 5V compatible TTL/CMOS - data/address buses. This 8bit bus monitor requires 5V external power supply. In the idle mode this unit draws 15mA of current and in working mode (when inputs get change) this may raise up to 20mA – 30mA. Due to this low power profile, this system can also attach into the PSU of the "testing system". This module is release as an open hardware project and it is covered with Creative Commons Attribution-ShareAlike 3.0 license . All the project related resources are available at Open Hardware Hub .

Kidogo is 8 channel USB self powered digital signal injector. Kidogo system consists with Signal Editor and USB interface module. Kidogo Player is the Signal Editor of the Kidogo system and it can support up to 512 time slots (each range between 1ms to 1s) with 8 channels. USB interface of the Kidogo system is based around Microchip’s PIC18F2550 microcontroller and generate 5V CMOS and TTL compatible outputs. Dimensions of current version of Kidogo USB interface is 53mm x 40mm (using standard through-hole components) and this can be reduce into more by using PCB layout based on SMD components. Kidogo Player is design to work under the Microsoft Windows operating systems and it has following general features: Save waveforms and settings as binary file (KDF file) or export waveform as a text file Playback controls such as “Play to segment”, “Play from segment”, “Step back”, “Step next” and “Clear” Shifting and rotating waveforms Invert, Reset, Clocking and Binary Generator functions Cop...

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.