The 8251 chip is Universal Synchronous Asynchronous Receiver Transmitter (USART). It acts as a mediator between the microprocessor and peripheral devices. It converts serial data to parallel form and vice versa. This chip is 28 pin DIP.The pin description of 8251A chipPinDescriptionD0 - D7parallel dataC/DControl register or Data buffer selectRDRead ControlWRWrite controlCSChip SelectCLKclock pulseRESETResetTxCTransmitter ClockTxDtransmitted dataRxCReceiver ClockRxDReceiver DataRxRDYReceiver ReadyTxRDYTransmitter ReadyDSRData Set ReadyDTRData Terminal ReadySYNDET/Synchronous Detect/BRKDETDetectBreakRTSRequest to send DataCTSClear to send DataTxEMPTYTransmitter EmptyVccVcc (5V)GNDGround(0V)Now let us see the functional block diagram of the 8251 chip.There are five different sections in this diagram. These sections are as follows −Read/ Write control logicTransmitter ReceiverData Bus ... Read More

In this section we will see how ADC (Analog to Digital Converter) works with Intel 8085 Microprocessor. The Analog to Digital Conversion is a quantizing process. Here the analog signal is represented by equivalent binary states. The A/D converters can be classified into two groups based on their conversion techniques.In the first technique it compares given analog signal with the initially generated equivalent signal. In this technique, it includes successive approximation, counter and flash type converters. In another technique it determines the changing of analog signals into time or frequency. This process includes integrator-converters and voltage-to-frequency converters. The first process ... Read More

In this section we will see how DAC (Digital to Analog Converter) using Intel 8051 Microcontroller. We will also see the sinewave generation using DAC.The Digital to Analog converter (DAC) is a device, that is widely used for converting digital pulses to analog signals. There are two methods of converting digital signals to analog signals. These two methods are binary weighted method and R/2R ladder method. In this article we will use the MC1408 (DAC0808) Digital to Analog Converter. This chip uses R/2R ladder method. This method can achieve a much higher degree of precision. DACs are judged by its ... Read More

In this section we will see how to write and execute programs for 8051 microcontroller using the Keil Software.Download KeilHere is the download link of Keil. You can download it and install it very easily. We are using C51 version for 8051 devices.https://www.keil.com/download/product/Use Keil to write programs for 8051 MicrocontrollerStart the Keil software. Go to the Project > New Project then choose a location to store your program, and give a name and Save.Now in the next window select the device from different manufacturers. We are selecting Microchip, and then by expanding we are selecting AT89C51 device and click ok.Now ... Read More

Here we will see how external RAM memories can be addressed by the Intel 8051 microcontroller. There are different methods for addressing the RAMs. Now at first we will discuss about some different types of RAM memories in short.The RAM (Random Access Memory) is volatile memory. So when the power is cutting off to the RAM chip, it losses the data. RAMs are also known as RAWM (Read and Write Memory). There are basically three kinds of RAMs. These are SRAM (Static RAM), NV-RAM (Non-Volatile RAM) and DRAM (Dynamic RAM).Static RAMThe storage cell in Static RAM are made of flip-flops. ... Read More

High level language is the next development in the evolution of computer languages. Examples of some high-level languages are given belowPROLOG (for “PROgramming LOGic”)FORTRAN (for ‘FORrmula TRANslation’)LISP (for “LISt Processing”)Pascal (named after the French scientist Blaise Pascal).High-level languages are like English-like language, with less words also known as keywords and fewer ambiguities. Each high level language will have its own syntax and keywords. The meaning of the word syntax is grammar.Now let us discuss about the disadvantages of high-level languagesA high level language program can’t get executed directly. It requires some translator to get it translated to machine language. There ... Read More

After machine level language, the next level of development in the evolution of computer languages was the Assembly Language. Machine level language uses only the binary language. But on the other hand, assembly language uses mnemonics or symbolic instructions in place of a sequence of 0s and 1s. As example, we can consider that, to add register A and B in a particular computer, assembly language uses the mnemonic ‘ADD B’ in place of 10001111. In assembly language, we use symbolic names to denote addresses and data. A number of such examples are dealt with in the successive chapters. Thus ... Read More

Computer can understand only the language of Digital Electronics. Digital Electronics deals with presence and absence of voltages. Within the computer there are two logics can play their role. These logics are −Positive Logic − Here presence of voltage will be denoted by 1 and absence of voltage will be denoted by 0Negative Logic −Here presence of voltage will be denoted by 0 and absence of voltage will be denoted by 1But obviously computer can follow anyone of the logics at a time, not both the logics simultaneously. To make the computer understand, a program can be written using only ... Read More

There are mainly three different languages with the help of which we can develop computer programs. And they areMachine Level languageAssembly Level Language andHigh-Level LanguageMachine Level LanguageThe computer can understand only the language of Digital Electronics. Digital Electronics deals with the presence and absence of voltages. Within the computer there are two logics can play their role. These logics are −Positive Logic − Here presence of voltage will be denoted by 1 and absence of voltage will be denoted by 0Negative Logic − Here presence of voltage will be denoted by 0 and absence of voltage will be denoted by ... Read More

Let us discuss Microcomputer, Microprocessor, and Microcontroller in this article and also to highlight their respective differences in between. MicrocomputerA microcomputer can be defined as a small sized, inexpensive, and limited capability computer. It has the same architectural block structure that is present on a computer. Present-day microcomputers are having smaller sizes. Nowadays, they are of the size of a notebook. But in the coming days also their sizes will get more reduced as well. Due to their lower costs, individuals can possess them as their personal computers. Because of mass production, they are becoming still cheaper. Initially, in the earlier ... Read More