USB to serial converter is a vital tool for every embedded system engineer and most probably you should be having a couple of them in your lab from many years. I have also been using USB to serial converter for years, I bought them ready made from the market. But this year I planned to make one my self, I was already familiar with the chips used on such converters. One chip which I like the most is FT232RL it works very well under modern OS like Windows 10 and driver installation is very easy. So I downloaded the datasheet and studied about its working details. Then I created a schematic for a basic breakout board that has a USB connector and a simple output connector for serial data. Serial data has only RX and TX lines that I can connect to micro-controller or other serial device. I am sharing the schematic of my board in this article. Fig. Schematic for FT232RL based USB to USART bridge module As you can see on the extreme left hand side I have a USB connector which allows us to easily connect this module to USB port of our PC. The FT232 chip has a feature to select i/o voltage level. I mean MCUs such as AVR PIC or 8051 usually needs 5v […]
Resistors are one of the most basic electronic component. They opposes(or resists) the flow of electric current through them, that is why they are named resistors. This article introduce you to resistors describing how they look, how to measure their value, how to solder them and how to identify them in a schematic. Read more about resistors.
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 […]
One of the most common place where small MCUs are used is to drive big seven segment displays in public area. For example the bank token number, flight or train schedule, train coach number, production volume (in factories), current forex(in banks) or gold rates etc. Since these are public display they should be big (and bright) enough to be seen from a distance of few meters. And due to their bigger size(and high brightness) they require 12V supply for each segments. Current requirement is also high. All these call for a sophisticated circuit, since these type of circuit is very common we have developed a compact board with integrated high voltage driver circuit coupled with an AVR 8 bit CPU. High Voltage Seven Segment Display Driver Board Further information, datasheet and user manual will be available as soon as the product is offered for sale. More Images
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 […]
This mini article provides a small circuit idea to interface a 12V or 24V DC Solenoid (or relay) with a 3.3 or 5V microcontroller’s i/o pins. Datasheets BD139 Power Transistor (For PINOUT refer this document)
This pictorial step by step guide you show you how you can connect a serial RFID Reader to your PC using USB Port. Before you begin please read the following tutorial on RFID Technology and its application to make yourself familiar with it. Interfacing RFID Reader with AVR Also you will need the following modules, they can be purchased from our online store. Fig.: Serial RFID Reader. Fig.: USB to TTL Converter. Fig.: RFID Tags (Comes with the Reader). The RFID Reader is used to read the tags. The tags can be used to identify peoples. For example in a electronic door lock, the user just need to bring a tag (which can be a card or keychain) near the antenna. The system identify the user and present a welcome message (like "Welcome Mr. Steve"), then it prompts for password. Its like your ATM card but the advantage is that you don’t need to bring it out from your wallet. Just touch the wallet to the antenna, and that’s it! The USB to TTL Module is used to connect the RFID reader to PC. Connect the RFID reader to USB/TTL Converter as show in in the image below. Fig.: Connections. The connection is simple. All the PIN names are written on the PCBs itself so no confusion while […]