PIC MCU Q A 80

1. After the following program segments are executed, (AA)= 9DH, W= 43H.

movlw c7h ;w=c7h

movwf aa ;aa=c7h

movlw 5ah ;w=5ah

xorwf aa，1 ;aa=9dh, w=5ahmovlw 0e3h ;w=e3h

subwf aa，0 ;aa=9dh, w=43h2, after the following program segments are executed, (count)= , (20h)= , (22h)= .

count equ 20h

org 0000h

movlw count

movwf 22h

movlw 22h

movwf count

At the beginning of the end paragraph, I don't know what is in w and can't be calculated.

3. After the following program segments are executed, w= a8h (fsr)= 72h 72h= a8h

movlw 72h ;w=72h

movwf fsr ;fsr=72h

movlw 0a8h ;w=a8h

movwf indf ;72h=a8h

The difference between the PIC microcontroller and the MCS-51 series microcontroller should be said to have three main features:

1) Bus structure: The bus structure of MCS-51 microcontroller is von Neumann type, and the computer takes instructions and data in the same storage space, and the two cannot be carried out at the same time; The bus structure of the PIC microcontroller is a Harvard structure, and the instruction and data space are completely separated, one for instructions and one for data, because the program and data can be accessed at the same time, so the data throughput rate is improved. Because of the Harvard dual-bus structure used in the PIC microcontroller, it is different from common microcontrollers

The program and data buses can be of different widths. The data buses are all 8 bits, but the number of bits on the instruction bus is different.

2) Pipeline structure: MCS-51 single-chip microcomputer adopts a single-instruction pipeline structure for finger picking and execution, that is, taking one instruction and then taking down the next instruction after execution; The PIC adopts a dual-instruction pipeline structure, and when one instruction is executed, the next instruction is allowed to be taken out at the same time, so that a single-cycle instruction is realized.

3) Register group: all registers of PIC microcontroller, including IO port, timer and program counter, etc., are in the form of RAM structure, and they only need one instruction cycle to complete access and operation; The MCS-51 microcontroller takes two or more cycles to change the contents of the register.

For more details, please refer to the relevant book.

Two different microcontrollers.

Two different types of microcontrollers; Microcontroller = microcontroller.

That's right, the higher the frequency, the faster the speed. Sometimes, however, it is not necessary to perform certain functions at such a high frequency. Because the higher the frequency, the greater the power consumption.

Take a look at the electrical characteristics at the back of the data sheet of the PIC microcontroller, and you can know that the current required by the power supply at a frequency of 1m or 32K is much smaller than that at 4m and 8m. Maybe you do the experiment and think that the extra few hundred microamps or milliamps are not worth saving. But in one industrial setting, engineers are stingy with 1ua.

The problem of power consumption is to consider a lot in the design, and now many single-chip microcomputer manufacturers tend to chip products in the direction of low power consumption.

Generally, single-chip microcomputers need a relatively high clock frequency when performing data communication and mathematical calculations, and in some ordinary standby, waiting for interruption and other states, they do not need such a high frequency, in order to save power consumption, the frequency is reduced. But at this time, the crystal oscillator has been welded next to the microcontroller, so you can let the program change the setting of the crossover and reduce the working frequency. Reduce power consumption.