51 single chip microcomputer precise delay procedure (crystal oscillator 12MHz, a machine cycle 1us.)Several precise delay procedures: in the calculation of accurate delay, the most easily overlooked is the calculation of the loop outside the part of the delay,This part does not affect the program in situations where the time requirement is not high.
A. 500MS Delay subroutine program:. (Crystal oscillator 1
In general applications (not using USB, the accuracy requirements are not high) the LPC17XX series in addition to using external crystals, the internal 12MHZ crystals can also be used as the oscillator source. In fact, before running the initialization program, before entering the user program (main function), LPC17XX is using an internal crystal, which is designed to allow the bootstrap code (commonly known as bootloader) to run on a known frequency.
The last edition uses the physics thought, this time uses the mathematics thought, if you have downloaded the first edition the code can obviously feel the mathematics powerful!!!!!
Here is the spring of the JS code:
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High Simulation spring oscillator (compressed use version) after setting up the new activation element and then point me!! Run please activate & Lt;br> initial speed (in pixels per millisecond): " move interval (in milliseconds): half
Crystal oscillator and Clock
The cc2530 has an internal system clock, or a master clock. The system clock Source is a 16Mhz rc crystal oscillator or 32MHz crystal oscillator. The clock can be controlled using the Clkconcmd special function register.
In addition, the chip also has a 32KHz clock source can be RC oscillator
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acquisition can be carried out strictly at the same time. PLL is a phase feedback automatic control system. It consists of the following three basic components: Phase detector (PD), Loop Filter (LPF), and voltage controlled oscillator (VCO).How phase-locked loops work:1. The output of the voltage-controlled oscillator is collected and divided;2. And the reference signal simultaneously input phase detector;
Crystal oscillator from the material can be divided into quartz crystal oscillator and ceramic crystal two categories, and from the properties of crystal oscillator can be divided into passive crystal and active crystal oscillator. Quartz crystal and ceramic crystal vibration from the appearance of very advantageous to
from the diagonal line of the bridge. When there is no input signal, because RC1 = RC2 has the same characteristics as the two tubes, the bridge is balanced and the output is zero. Because it is connected to a bridge, zero point drift is also very small. The difference amplifier has good stability, so it is widely used.
5. Integrated Operational Amplifier
An integrated operational amplifier is a kind of device that makes a multilevel dc amplifier on an integrated chip and can complete various
I. Clock
1. Three different clock sources can be used to drive the system clock (sysclk ):
. HSI oscillator clock high speed internal
. HSE oscillator clock high speed external
. PLL Clock Phase Locked Loop
2. These devices have two secondary clock sources:
. 32 Khz low speed internal RC [1], can be used to drive independent watchdog and RTC. RTC is used to automatically wake up the system from the stopped/
example, inSampleSize == 4 returns122 * an image that is 1/4 the width/height of the original, and 1/16 the123 * number of pixels. Any value
InJustDecodeBounds can obtain the image size without allocating resources to the image.InSampleSize: Calculate the image compression ratioOpen-source projects such as xutils, Universal-Image-Loader, and Foursquare perform similar operations on big charts.The code for Foursquare to process a large image is as follows:
public class ImageU
Recently looking at the system clock, the Internet to find a few about the phase-locked loop data, a document, feel that they understand, share out
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PLL (phase locked loop) circuit principle
In the communication machine and other used oscillation circuit, it requires a wide frequency range, and frequency stability is high. No matter how good the LC oscillation circuit, its frequency stability, can not be compared with the crystal oscillation circuit. However, the frequency of the crystal
two streams (input stream, output stream);2) associated with the buffer, (this step can be omitted only to speed up the copy).3) Start copying.A MP3 Copy example is shown below:package Io.dol.sn;import Java.io.bufferedinputstream;import Java.io.bufferedoutputstream;import Java.io.FileInputStream; Import Java.io.fileoutputstream;import java.io.ioexception;//Add buffer to manipulate byte stream, copy 1.mp3 to 2.mp3public class Bufferioputstreamdemo {public static void main (string[] args) {Buffer
Temperature- compensated crystal and pressure-controlled temperature-compensated crystal oscillator is in the active crystal oscillator, is the highest precision, the lowest power consumption, jitter the smallest active crystal, precision is usually between the 0.5ppm to 2.0ppm range, therefore, in the temperature change in the big time, can be stable temperature control within the specified range. Although
From: http://bbs.cechina.cn/ShowTopic.aspx? Id = 2694
1
Basic components of the. PLL
Many electronic devices usually need to synchronize external input signals with internal oscillating signals, which can be achieved through the phase-locked loop.
The phase-locked loop (PLL) is a feedback control circuit ). The Phase-Locked Loop uses external input reference signals to control the frequency and phase of internal oscillating signals in the loop.
Because the phase-locked loop can automatically tr
This article is about the 1937 timer, just beginning to be crystal oscillator frequency, clock frequency, oscillation period, oscillation frequency, instruction period, instruction frequency and so on the noun around halo. First to solve this problem.Crystal oscillator frequency is the frequency of the oscillator, that is, the frequency of the crystal
basic operation of the time spent, generally using microseconds to measure the speed of single-chip microcomputer,
51 single-Chip machine cycle includes 12 clock oscillation cycle, that is, if the 51 microcontroller using 12MHz crystal, then the implementation
A machine cycle requires only 1μs, and if you are using a 6MHz crystal, it takes 2μs to perform a machine cycle.
2. Instruction cycle refers to the time required for a single-chip microcomputer to execute an instruction, generally using a
Collect collected information from the Internet:
How can I determine whether the crystal oscillator is working properly?
1. There are many judgment methods. It is most direct to view the waveform with an oscilloscope. You can also test the voltage with the voltage file of a digital multimeter. Because the duty cycle of the crystal oscillator waveform is 50%, therefore, the average voltage measured is about
up a so large array?! byte[] buf = new Byte[num];int len = 0;while ((Len=fis.read (BUF))! =-1) {System.out.println (new String (Buf,0,len));}} catch (IOException e) {System.out.println ("File creation Failed");} finally{try {if (FIS! = null) {Fis.close ();}} catch (IOException E2) {System.out.println ("file close Failed");}}}9, the use of byte stream to achieve the copy operation of the file Bufferinputstream, Bufferoutputstream1) Creation of two streams (input stream, output stream);2) associa
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