micro controllers & applications

8/2/2019 Micro Controllers & Applications

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TRR ENGINEERING COLLEGE [email protected]

MICROCONTROLLERS

ANDAPPLICATIONS

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1. What are 8051 microcontrollers Internal and External memories?

Ans. The 8051 has three very general types of memory. To effectively program the 8051 it isnecessary to have a basic understanding of these memory types.

The memory types are illustrated in the following graphic. They are: On-Chip Memory, ExternalCode Memory, and External RAM.

On-Chip Memory refers to any memory (Code, RAM, or other) that physically exists on the

microcontroller itself. On-chip memory can be of several types, but we'll get into that shortly.

External Code Memory is code (or program) memory that resides off-chip. This is often in theform of an external EPROM.

External RAM is RAM memory that resides off-chip. This is often in the form of standard static

RAM or flash RAM.

2. Write the signal description for TXD?

A. The pin 11 (p3.1) of 8051 microcontroller can be used as TXD. This pin is used to transfer

output from microcontroller for serial data transmission.

Initially the serial data in SBUF register then the contents of this register are transmitted to

output device serially (bit by bit).

At the end of the transmission T1 (Timer Interrupt) flag will be set.

4. 8051 microcontroller interrupts?

Ans. 8051 provides 5 vectored interrupts. They are -

1.2. TF03.4. TF1

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5. RI/TIOut of these, and are external interrupts whereas Timer and Serial port interrupts aregenerated internally. The external interrupts could be negative edge triggered or low level

triggered. All these interrupt, when activated, set the corresponding interrupt flags. Except for

serial interrupt, the interrupt flags are cleared when the processor branches to the InterruptService Routine (ISR). The external interrupt flags are cleared on branching to Interrupt ServiceRoutine (ISR), provided the interrupt is negative edge triggered. For low level triggered external

interrupt as well as for serial interrupt, the corresponding flags have to be cleared by software bythe programmer.

4. What is Free running counter in 8051?

Ans. The Counter Free-Running block counts up until reaching the maximum value, 2Nbits

1,where Nbits is the number of bits. Then the counter overflows to zero and begins counting up

again.

After overflow, the counter always initializes to zero. However, if you select the global doublesoverride, the Counter Free-Running block does not wrap back to zero.

5. How printer inter faces to 8051MCU?

Ans. Printer has 8 data lines, and we use two control signals, busy and strobe. Busy pin is madeinput and strobe as output. First strobe pin is kept high, data to be printed is obtained at particular

port then, low to high transition is given to the strobe. then we keep checking the busy pin, ifprinter is busy then wait, after it becomes free then send next data. for printer interfacing we

used DB25 connector.

6. What is Real-Time Operating Systems in Microcontrollers?

Ans. Real-time embedded systems serve various purposes, such as to control or process data. A

real-time operating system is a piece of software with a set of APIs that developers can use tobuild applications. RTOSs support the need of some embedded systems to meet deadlines.

However, using an RTOS doesn't guarantee that a system will always meet the deadlines,because these systems also depend on the overall system's design. Although RTOSs for

embedded systems are predominantly used in high-end microprocessors or microcontrollers with32-bit CPUs, there is a growing trend to provide these features in mid-range (16-bit and 8-bit)

processor systems

7. What is RTX51 Tiny Real-Time Kernel?

Ans. RTX51 Tiny is a small real-time kernel designed for single-chip applications where code size is the

most important factor. The RTX51 Tiny kernel requires only 900 bytes of code space and is well-suited

for applications that don't need RTOS features like messaging, semaphores, and memory pool

management.

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RTX51 Tiny was designed for single-chip applications where no XDATA is available. However,

RTX51 Tiny may be used with any 8051 target system.

8. What is ARM microcontroller?

Ans. The microcontroller is a general purpose 32-bit microprocessor, which offers highperformance and very low power consumption. The ARM architecture is based on RISC

principles, and the instruction set and related decode mechanism are much simpler than those ofmicroprogrammed CISCs. This simplicity results in a high instruction throughput and impressive

real-time interrupt response from a small and cost-effective processor core.

A 5-stage pipeline is employed so that all parts of the processing and memory systems canoperate continuously. At any one point in time, several operations are typically in progress:

subsequent instruction fetch, next instruction decode, instruction execution, memory access, andwrite-back.

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