Dilshan R Jayakody’s Web Log

This is oscillator controller for 8bit PIC microcontrollers which is specifically design to debug MCUs and related circuits by without using ICD unit. This unit consists with low speed oscillator and cycle counter with automatic hold. In current version, oscillator is capable to run in 2 frequency modes and it can count up to 4096 cycles in each run. The number of frequency modes can be extend by adding more capacitors and the upper limit of cycle counter can be increase by adding more 12bit counters (and related circuitries) to the system. Oscillator waveform in low frequency mode In current version oscillator can be run in either 66 Hz ~ 70 Hz or 666 Hz ~ 670 Hz ( aprox. ). This frequency can be adjusted by changing the value of C1 or C2 capacitors (e.g: 0.1MFD can generate 6.39 kHz output signal) OR by replacing R1 with some suitable variable resistor. In project package we include sample PIC16F84A based project to test with this system. The recommended test attachment i...

This is a simple microcontroller base implementation to drive 2 digit 8 pin seven segment display (SSD) unit. For this implementation we use Microchip’s PIC16F84A – 8bit microcontroller unit and Proton+ PICBASIC compiler. Compared with other SSD units this SSD unit needs special algorithm to drive it. Some of the logical procedures to drive this SSD unit are illustrated in below, This illustration is valid only for single digit of target SSD unit and it can easily expand to 2 digits by activating pin no 5 and 6 with appropriate inputs. In attached design we use PIC16F84A MCU with 4 × 2SC945 general purpose NPN transistors to drive this TOD-4201LR SSD unit. This proposed system is design to work with +5V DC power supply and may not need any additional data source. Supplied software for this project is for demonstration purposes only and it perform counting from 0 to 99 and then reset back to 0. To generate the output user need to assign required number to the value variable an...

After the 2 weeks of continues development we finally design suitable RC remote control system for cars. This RC system has, Battery eliminator circuit (BEC) Control System 433MHz transmitter and receiver module Motor driver and servo controller In this design both transmitter and receiver modules are based on seeed studio’s 433MHz RF link kit and control systems are based on microchip’s PIC16F84A MCU. At the design time we test this circuit with Futaba, Airtronics, JR-Radios, HiTec and "Mystery" (available in eBay) micro-servo units. This circuit may support standard electric motors (brushed DC motors) and during the testing stages we drive RC helicopter motors and RC airplane motors successfully with this system. To drive this circuit we use 7.2V 500mAh Li-Po batter pack. During the circuit assembling and testing, make sure to take necessary actions (e.g: shielding) to prevent/minimize the EM interferences which was generated by the motors. Most of the time t...

In this project we design 9 pin Microsoft Windows NT compatible dot matrix printer using two PIC16F84A microcontrollers. Printer mechanism is based on old Commodore dot matrix printer. At the moment this device support for Microsoft Windows 2000 and XP operating systems. Other most notable features of this implementation are, Drive 18V - 9pin magnetic dot matrix head unit Handle 12V paper feeder and head movement stepper motors Support A4 and compatible page formats System drives using 240V - 18V step-down transformer Audible warning system Low power consumption due to CMOS implementation Works with Standard Printer Port In this implementation we use Microsoft Windows Driver Development Kit (DDK) with Microsoft Visual C++ to create device driver for the system and use Delphi 7 to create front end application (printer maintenance – control panel applet). Both microcontrollers are programmed using MPLAB – ASM. In this system we use 2 microcontrollers with 7MHz oscillators, One PIC16F84A ...