Dilshan R Jayakody’s Web Log

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 .

Automated Home Security system is PIC16F877 based security system with following core features, Support automatic phone dialing using DTMF tones Support inputs from three optical sensors Control external device(s) Built-in alarm with external audio output Allow total customization to the end-users (such as program phone numbers, setup device control sequence, etc) without changing the source code. Password protected system setup In this design we use PIC16F877 8bit microcontroller as main system controller, NE556 dual timer as an alarm system and 7805 as power regulator. To miniaturize the final product we use some amount of surface mounted parts with this design. Application program(s) of PIC microcontroller is developed using C programming language and release under the terms and conditions of GNU General Public License. In this design we use some special electronic components/modules which include LCD display module, 4x4 keyboard matrix, telephone isolation transforme...