R-B | Embedded Lab

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Lab 13: Read and Write to internal EEPROM

Posted on May 4, 2011 by R-B 15 comments

EEPROM (Electrically Erasable Programmable Read-Only Memory) is a type of non-volatile memory which can be programmed, erased, and re-programmed electrically while it is on the circuit board. A majority of PIC microcontrollers come with some built-in EEPROM which is a great place to store data that should not be lost when the system is powered down. A good example is a digital lock system where the access code can be stored in the EEPROM of microcontroller so that the contents remain intact even after the power supply has been removed. In my ‘Beginner’s data logger‘ project, I used the internal EEPROM of PIC12F683 to store the measured temperature values. In today’s experiment, we will learn how to perform the basic Read and Write operations to the internal EEPROM of PIC16F628A.

Read/Write operation with PIC's internal EEPROM

Lab 12: Basics of LED dot matrix display

Posted on April 28, 2011 by R-B 49 comments

We covered how to interface seven segment LED displays to a PIC microcontroller in two sections: Lab 6 and Lab 11. Today, we will move on to interfacing an LED dot matrix display. LED dot matrices are very popular means of displaying information as it allows both static and animated text and images. Perhaps, you have encountered them at gas stations displaying the gas prices, or in the public places and alongside highways, displaying advertisements on large dot matrix panels. In this experiment, we will discuss about the basic structure of a monochrome (single color) LED dot matrix and its interface with a microcontroller to display static characters and symbols. We will cover the animation stuff in next tutorial. I am using the PIC18F2550 microcontroller on the StartUSB for PIC board for demonstration, but this technique is applicable to any other microcontrollers that have sufficient I/O pins to drive the LED matrix.

Interfacing a LED dot matrix display with a PIC microcontroller

How to make a contact-less digital tachometer using IR-light reflection technique

Posted on April 21, 2011 by R-B 41 comments

Tachometer is a device that measures the rotational speed of any shaft or disc. The unit of the measurement is usually revolutions per minute or RPM. The traditional method of measuring RPM of a rotating shaft was based on velocity feedback concept where a dc generator is hooked to the rotating shaft so that the voltage induced across the generator’s terminals is proportional to the speed of the shaft. Today, we are going to make a digital tachometer based on a PIC microcontroller that requires no physical contact with the rotating shaft to measure its rotational speed. The physical contact is avoided by using an optical detection technique that requires an infrared light emitting diode in conjunction with a photo detecting diode. StartUSB for PIC from mikroElektronika is the main controller board used in this project. To read more about this board, visit my article Getting started with PIC18F Microcontrollers. This tachometer can measure speeds up to 99960 RPM with the resolution of 60 RPM. The result is shown on a 16×2 character LCD display.

Contact-less digital tachometer using StartUSB for PIC and optical sensors

2 in 1 : Tetris and Snake with one AVR

Posted on April 19, 2011 by R-B 2 comments

This project describes two games – Tetris and Snake, both programmed inside an Atmega168 microcontroller. You can plug this device to a PAL TV and have fun playing the games. The circuit diagram is very simple and uses resistors to generate composite video output.

Tetris and Snake inside one AVR

Make your own motion sensor alarm with SMS feature

Posted on April 15, 2011 by R-B 3 comments

MikroEleketronika demonstrates how to build a simple home alarm system that has the capability of sending SMS to a predefined cell phone number when intrusion is detected. This project is based on StartUSB for PIC board, a small development board for PIC18F2550, which is preprogrammed with an USB bootloder so that no additional programmer is required to load the firmware. The SMS portion uses a SmartGM862 Board, which is a full-featured development tool for the Telit’s GM862 GSM/GPRS module. All the boards required for this project can be purchased as SMS Home Alarm Kit from mikroElektronika. A demonstration software for PIC is also available for free. They are offering free shipping now.

DIY home alarm kit

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