Category Archives: Hardwares

Door Entry Detection for MCU Based Designs

This article discuss how you can detect the entry of a person in a room and get this signal inside your MCU. This is NOT a complete project but just an idea that can be implemented in many different projects. The technique is to use use an IR transmitter and a receiver pair. One side of door will have an IR Transmitter and the other side of door will have an IR Receiver. The transmitter (Tx in short) will continuously send IR beam to the receiver, as long as the receiver(Rx in short) will receive this beam it will give a voltage output in range of 2.5v to 3.0 volts. But as this beam is obstructed, for example by someone entering the room, the receivers output will tend towards 4.5 Fig. 1 – Schematic For Door Entry Detection The IR Transmitter can be made on a small PCB as shown below. It has four mounting holes to fix it in the wall near the door. Please use 1 Watt resistor for R2 and R3 (22ohms). Fig. 2 – IR Transmitter Module Similarly the IR receiver module is made. Fig. 3 – IR Receiver Module.   Mount the IR Transmitter and Receiver as shown in the image below. Fig. 4 – Mounting the Modules on Door. As you can see the […]

DS1307 Based RTC Module

An RTC Module or a Real Time Clock Module helps a system keep track of current time (hour, minutes and seconds). It automatically increments the time without any help from the host (microcontroller). Other benefit is that it has a backup power supply from a small coin cell that help it maintain the time in absence of power. It needs very small power in backup mode so that the coin cell last for years! One such RTC IC is DS1307. It communicates with the host using I2C serial interface. We have put all the required components in one PCB to make a neat module that we can hook up to our MCUs like PIC or AVR. After the experiment you can put the module safely in your drawer, bring it out after an year and still it will give you the correct time! DS1307 Module Schematic DS1307 Based RTC Module Schematic DS1307 Module Fabricated ! DS1307 Based RTC Module   Professional DS1307 RTC module     Connection with MCU The SCL line of RTC Module will be connected to SCL line of MCU similarly the SDA line will be connected to the MCU’s SDA line. The RTC Module should be powered from the microcontroller development board. Most of our boards have extra 5v output points. Please see their documentation for […]

GSM-GPRS Module SIM300

GSM-GPRS Module SIM300 with sim card holder, RS232 interface, power supply, buzzer and audio interface. Nice for learning the SIM300 module. You can connect this to PC using a USB to Serial Adaptor and use terminal programs such as Realterm to send receive data. Buy SIM300 Module from our store.

New 28 PIN AVR Development Board

We have launched a low cost 28 PIN AVR Development board for those you want to get started with AVRs on a budget. As this board provides a clean circuit for basic AVR connection you can learn to program hello world app (a LED blinky) in just few hours! If you are tired of wiring the basic AVR connection for every project, this board can save you a lot of time. You can order it from the online store and pay using Indian Debit Cards (or ATM Cards) or Netbanking. The board will be delivered to your door steps in 3-5 days any where in India. 28 PIN AVR Development Board.   28 PIN AVR Development Board. Buy 28 PIN AVR Development Board at Rs. 249 Only Features: Compatible with 28 pin chips like ATmega8,ATmega48,ATmega168, ATmega328 etc. Atmel AVR ATmega8 28 PIN microcontroller Included. 16 MHz crystal for maximum speed. All ports available on standard 0.1inch (2.54mm) male headers. LC Filter on AVcc for clean ADC performance. Decoupling capacitors on all power pins. Standard ISP Header (Can be programmed with our USB AVR Programmer v2.0). On/Off switch. 9-18V DC input. 5v regulated output for supplying extra peripherals.(3x). Reset Button. Power Indicator LED. Free Prototyping area for customization(78 holes at 0.1 inch distance) FR4 PCB with solder mask and silkscreen. All […]

RS232 Communication – The Level Conversion

Hello and welcome back. Continuing our discussion on RS232 serial communication in this part we will make a RS232 level converter. In the last tutorial we saw that how RS232 level signals differs from normal logic signals. So to interface RS232 level signals to our MCUs we need a "Level converter". And in this tutorial we will make one. What a level converter will do is to convert RS232 level signals (HIGH=-12V LOW=+12V) from PC to TTL level signal (HIGH=+5V LOW=0V) to be fed to MCU and also the opposite. Fig – Working of RS232 level converter       As RS232 is such a common protocol there is a dedicated IC designed for this purpose of "Level Conversion". This IC is MAX232 from Maxim. By using charge pumps it generates high voltages(12V) and negative voltages(-12V). Now lets make it! Things you need S.No Item Value Qty 1 MAX232 IC 1 2 Capacitors 1uF 4 3 10uF 1 4 DB9 Female Connector 1 5 General Purpose PCB 1 6 Some Wires – -   Fig – Stuffs required for RS232 level converter.     Now having all the stuffs in our working table lets begin. The Schematic Fig – Schematic for RS232 level converter.     Assembly Assemble the circuit according to the schematic on a small piece of general […]

Home Made AVR Devboard

In this article, I will show you how to make your own AVR development board for ATmega8 microcontroller. What is a development board? In order to learn any MCU like AVR we need a AVR MCU that has all the basic connections like power supply, crystal oscillator, proper reset signal and an ISP connector for uploading a program. All these things are required for any project you will make. A development board is a circuit board that contains all these connections and it has connectors for IO pins of MCU so that they can be connected to any external circuit with ease. So as you see its is like a basic framework. Once you make a good development board and test it, you will have a solid foundation and for your project you can concentrate on the specific requirement of that project. This will also reduce the chance of making errors. Some more complicated development boards have a RS232 level converters(for serial communication) ,motor control chips etc. Now let’s do it! I have described the basic connections required by any AVR MCU in Part III of my AVR tutorial series so I am jumping right to the schematic. Fig – Development board schematic. Things you need are S.No Components Name Value 01 ATmega8 IC1   02 Voltage Regulator IC7805 IC2 […]