MCU Circuits
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If the piclist is an any indication the 16f877 seems to be the new favorite hobby microcontroller, a position that used to be occupied by the 16f84/16c84. Compared to is older brethren the 16f877 has much more to offer at around twice the price. As for all.... -
This document describes the HSETI PCB. This PCB is a small simple application for the Atmel AT89C2051 microprocessor - a 20 pin 8051 variant, with FLASH (reprogrammable) program memory. The board has just two chips on it, the CPU and a driver/buffer... -
In many applications, a single on/off button switches the power supply on or off. Usually, the system switches off regardless of the processing function or workload the microcontroller or DSP circuit is currently handling. The small circuit in Figure 1 is.... -
To maintain content in the event of power loss, many designs that include SRAM require a dedicated device that can automatically switch from a standard power supply to battery operation. Microcontrollers seldom find use in power-switching applications.....
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In many µC applications, a signal conditioner modifies an analog input signal from a sensor and passes it to the µC for processing. The last stage of the signal conditioner is always a device that transforms the signal level to a value acceptable for the....
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Finding out where your microcontroller`s firmware spends most of its time can be a tedious task when you use a conventional in-circuit emulator and breakpoint techniques. Other such tasks include discovering why a state machine doesn`t work as you intended....
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For designers of radar or sonar echo-ranging systems, an echo imitator can ease development and adjustment chores by generating a controllable pulse that's similar to an incoming echo signal. A decade ago, you'd probably use several 555 timers and their....
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OSU8 began as a student project in 1994 to create a simple but functional 8-bit microprocessor, starting with a definition of the architecture to implementation in a Xilinx FPGA chip, and full-custom CMOS implementation. Over a period of about six months,.... -
After reading the Mobile Robots Book, written by Joseph L. Jones and Anita M. Flynn, and get the Interactive-C file from ftp://cher.media.mit.edu, I found a very nice S19 downloader written by Randy Sargent. I started to download the pcode to my HC-11 board,.... -
A microcontroller, by default, can execute only one program at a time. What do you do if, in a given project, you need to perform more than one operation at a time? Add more microcontrollers to the design? In certain cases it`s unnecessary...
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With the proliferation of dual-voltage architectures and multiprocessor boards, even simple applications can require several processor voltage rails. With each processor having its own power-up and -down requirements, power-rail sequencing and control can....
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Figure 1 shows an efficient and cost-effective frequency counter using an Atmel 89C2051 µC (Reference 1). The design can use any µC of the 8051 family. The circuit counts frequency and sends the count to a PC via the serial port. The signal connects to pin....
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In designing µC-based systems, you often face a situation in which the µC has to respond to an external event happening at an uncertain moment in time. One example is receiving an echo from an object in a pulse-range measuring system. In these situations,....
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Some microcontroller applications usually use too many I/O pins to read keys or onboard switches; in many cases, few pins remain available for other uses. Some alternative ways to read keys yield more free pins. First, consider some ways to effect key....
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The major building blocks for a white-LED driver are an oscillator, a charge pump, and a regulated current source. National Semiconductor (www.national.com) produces a device that contains all these building blocks in the highly integrated LM2791/2 IC. You....
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The traditional frequency multiplier requires many elements: a phase comparator to detect the phase error between the input and the output signals, a lowpass filter to convert the phase error to a dc control signal, a VCO to generate the output, and a....
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RS-232 is the most common serial interface in the PC world. Most RS-232 interfaces communicate with the receiver at a fixed transmission rate, such as 9600 baud. But what happens if the transmitter operates with different transmission rates? Different....
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A project required an inexpensive oscillator whose frequency increased step by step from 200 to 400 Hz and then decreased to 200 Hz. The first step was to design a VCO with a staircase driver. However, this approach entailed at least four ICs and many....
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Driving a bare LCD does not necessarily require specialized interface circuitry or peripherals. This Design Idea describes an alternative drive scheme, which you can easily implement using the general-purpose outputs of a microcontroller. Many....
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The use of public-key-encrypted algorithms within licensed applications can prevent hackers from cracking the licensed algorithms. Moreover, you can use them to disable licensed features that a user doesn`t purchase. Licensing schemes eventually arrive at....
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There is enough of poorly constructed RS232 alike TTL level interfaces (+5volt) , this one generates it`s own +/- 10..11volts as RS232 specs. require , and is able to use very long cables like RS232 can , and protects computer as well , nice in funny.... -
A discussion recently on the mp3projects discussion board, about using DRAM memory with small 8-bit processors without DRAM controllers, got me to take up an old idea. I thought it should be possible to hook up a DRAM to a small processor (in this case an.... -
The potentiometer portion of a mixed-signal, digitally programmable potentiometer adds variability to an analog circuit, and its digital controls provide programmability. You can use a digital potentiometer in two ways in an analog circuit. You can use it as....
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This is the hardware and source code for an Atmel ATmega8 / MX-614 based UI only TNC. The intent was to provide inexpensive basic TNC functionality for APRS related packet activities. We also have the flexibility to modify the operations of the TNC by....
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This was my second Nixie clock project. I wanted something a little smaller / cheaper / simpler then my rather large B-7971 clock. I will post the design for that one of these days. I was trying to simplify everything. And basically wound up with a one chip....
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A basic circuit of the 89C2051 shown here can be made easily using point-to-point soldering with a universal PCB. Use an ordinary 20-pin socket, do not use a circle-pin socket. D1 is a small dot LED. U2 can be either 7805 or 78L05. U3 is optional for.... -
This single sided proto board provides an economical solution for developing and testing the projects around Atmel 20 pin series u-controllers (89Cx051 & AVR).. -
This is my long history the device that controls my home`s night light, air-conditioner,etc. The device is a Miniature Real-time Controller. The circuit uses only three chips, a 89C2051, DS275(or MAX232), and 74LS07 open collector driver. The scheduler for.... -
The link shows how to inteface Alphanumeric LCD to 8051 Microcontroller. Liquid Crystal Display also called as LCD is very helpful in providing user interface as well as for debugging purpose. The most common type of LCD controller is HITACHI 44780 which.... -
Relays are devices which allow low power circuits to switch a relatively high Current/Voltage ON/OFF. For a relay to operate a suitable pull-in & holding current should be passed through its coil. Generally relay coils are designed to operate from a.... -
The Tutorial shows how to interface 7-segment display to a microcontroller. Also explains how do display more than one 7-segment on same data lines using scanning method. 7 Seg displays are are basically 7 LED's. It will be much easier to understand if you.... -
This Project Automatic Room Light Controller with Visitor Counter using Microcontroller is a reliable circuit that takes over the task of controlling the room lights as well us counting number of persons/ visitors in the room very accurately. When somebody....
New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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