Dilshan R Jayakody’s Web Log

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...

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 2 channel D.C motor controller with pulse width modulation (PWM) based speed and direction control. This module is mainly design to drive 14.4V to 18V electric D.C motors. This motor controller is design to work with 18V - 1.5A D.C power source and it can be directly interface with general microprocessor / microcontroller system (without using any voltage level shifters). While at the prototyping stages we successfully couple this module with several NIDEC D.C fans and blowers which include D1751M24B7AP, E1331K12B7AZ-00, DME37KA, CF24DM506, etc. Control interface for this module is easy to use and at the designing stages we interface it with PIC16F887 and Atmega64 MCUs. Control interface of this module is consisting with 3 inputs (please refer the J3 in the circuit diagram) and using these inputs user may be able to select the motor, apply the brakes and also change the rotational directions of the motor(s). When constructing the circuit it is recommend...