Found 409 Articles for Microcontroller

In the last three clock cycles the instructions ‘MVI M, 25H’ are the example for Memory Write machine cycle. We have shown the Waveforms for MW machine cycle are shown in fig below.The address which is sent out from the register pair in a Memory Write machine cycle is completely dependent on the MW machine cycle under the consideration as it is shown in the chart below.Reg. pairExampleSPWe push the information above the top of the stack in PUSH BHLWe save register C in the memory which is pointed by HL in MOV M, CBCWe save register A register in the ... Read More

The last three clock cycles in ‘MOV C, M’ instruction are the example for Memory Read machine cycle. Waveforms for Machine Read machine cycle is shown below: InstructionOperationAddress reg.LDA 1234HLoading W with 12H (or Z with 34H)PCPOP BPopping information from stack topSPMOV C, MLoading A from memory pointed by HLHLLDAX BLoading A from memory pointed by BCBCLDAX DLoading A from memory pointed by DEDELDA 1234HLoading A from memory Location 1234HWZ The data, which is received in a register during a Memory Read machine cycle depends on the MR machine cycle within an instruction as shown below. Where ‘r’ stands for any of ... Read More

The OF machine cycle are constituted by the four clock cycles shown in the figure below. Here in these four clock cycles we execute opcode fetch, decode, and complete the execution. Moreover, in the instructions of 2- and 3-byte, and also in the instructions of 1 byte like ‘MOV B, M’, only OF and decode operations gets completed in these four cycles of the clock. Hence opcode fetch is consisted by the OF machine cycle and for performing the decode operation, and in some rare cases execution. For performing some typical instructions like DCX B, the six states are provided ... Read More

In a matrix keyboard there are keys which are arranged in the form of a matrix which consists of several rows and columns. In the figure which is stated below significantly indicates the interfacing process of a matrix keyboard which consists four rows and four columns respectively. We connect a key at the intersection of every rows and columns. Hence there is a total of 4 × 4 = 16 keys in the given matrix. The lines of the columns get connected to Gnd through pull-down resistors.Even there is a matrix size were to be 8 × 8, for a sum ... Read More

A keyboard is a very common input device. We assume that there are only eight keys for the simple keyboard. Whenever a key is pressed on this keyboard by the user, the microprocessor immediately identifies which key is pressed. The action which is to be performed by the processor depends on that particular key that gets pressed. An example to be cited as on a particular keyboard for calculator the addition operation gets performed when we press the ‘+’ key. Moreover, a microprocessor does not get directly communicated by the input device it is done via the input port. The ... Read More

Intel 8279 is a specially designed Input Output port chip which performs two major functions. It scans a matrix keyboard, as well as it displays a multiplexed display such that the processor gets relieved from the extreme tasks and let it performs systematically. We had given a brief description about the working of 8279 as we have indicated in the following paragraphs.We continuously scan an 8279 matrix keyboard. During the scanning process, if a key gets pressed on the keyboard a scanning is performed again about 10 μs, resulting bouncing of the key to die down. If it is found ... Read More

In this module we have explained the complete interface of four numbers segmented into seven parts having the Light Emitting Diode which uses a serial data transfer scheme. The portion which is displayed of the interface has 4 LEDS comprises of 7-segments LEDs as we can see from the physical layout of the interface. The connection to the interface is done by the ALS-8085 kit which uses a flat table of 26 crores. We connect the connector C1 to the interface to the Input Output connector P3 on the ALS kit. There is a power supply of of +5 V ... Read More

In mode 0 or mode 1, a port works as an input port or an output port. It is dependent if an input device or an output device gets connected to the port. Moreover, this, mode 2 is often called as bi-directional handshake Input Output. It is beneficial for us when the microprocessor receives information, and sometimes sends information to the Input Output device which is connected to 8255. An example to be cited as for the communication process with a floppy disk controller card. Since mode 2 is bi-directional handshake Input Output, it needs more number of handshake lines ... Read More

 An output device which is very common is, especially in the kit of 8085 microprocessor and it is the Light Emitting Diode consisting of seven segments. Moreover, we have eight segments in a LED display consisting of 7 segments which includes ‘.’, consisting of character 8 and having a decimal point just next to it. We denote the segments as ‘a, b, c, d, e, f, g, and dp’ where dp signifies ‘.’ which is the decimal point. Moreover, these are LEDs or together a series of Light Emitting Diodes. We have shown the internal circuit comprising of a display ... Read More

We call mode 1 as the strobed Input Output or handshake Input Output. We use this mode when the data is supplied by the input device to the microprocessor at irregular interval of time. A port which is functioned to program in mode uses three handshake signals. These handshake signals are provided by Port C. Only port A and B works in mode 1. The pins PC2, PC1, and PC0 provides handshake signals for port B when we configure it for Input port or Output port. Moreover, the pins PC7, PC6, and PC3 provides handshake signals for port A. The ... Read More