System Clock Problem 20, System Clock Issue

This situation is mainly caused by the large traffic of the server responsible for timing and the inability to respond in time, and we can also make XP and the server of the National Time Service Center of the Chinese Academy of Sciences to match the time, because it is a domestic server, and the traffic is relatively small, so the success rate of timing is still quite high. The method is very simple, directly enter the IP address of the national time service center server in the "Server" column in Figure 4, and then click the "OK" button to save it.

Resources.

Press the DEL or F2 key to enter the CMOS when starting, and it is best to set it from the CMOS!

What is a System Clock? What is a Clock System?

The system clock is usually referred to as a clock system, which is a circuit composed of an oscillator (signal source), a timing wake-up device, a frequency divider, etc. Commonly used signal sources are crystal oscillators and RC oscillators.

What does a clock system do?

The clock is the pulse processor core of the embedded system to complete the execution of instructions, state change and other actions under the clock drive, and the peripheral components to complete various tasks under the drive of the clock, such as the sending of serial port numbers, a d conversion, timer counting, etc. Therefore, the clock is very important for the computer system, and usually the problem of the clock system is fatal, such as the oscillator oscillation is unstable and does not vibrate.

ARM's clock system consists of four parts, which are divided into a crystal oscillator, a wake-up timer, a phase-locked loop (PLL), and a VPB divider. The crystal oscillator provides the basic clock signal for the system (the frequency is FOSC). When the reset or the processor wakes up from power-down mode, the "wake-up timer" counts the clock signal to give time to initialize the components inside the chip.

The FOSC is then boosted by the PLL to a frequency that meets the user's needs, and FCCLK is used for the CPU core. Because CPU cores typically work faster than peripheral components, the user can set up a VPB divider to reduce the FCCLK signal to a suitable value FPCLK that is used for the peripheral component.

1.There are 60 squares on the clock face. The hour hand travels 5 divisions in 1 hour and 1 12 divisions per minute.

The minute hand moves 1 block per minute.

At 2 o'clock, the hour hand exceeds 10 divisions of the minute.

Set to be x minutes, and the hour and minute hands coincide.

1*x=10+1/12*x

x=120/11=10+10/11。

That is, at 2 o'clock (10 and 10 11), Master Wang began to work.

Thus, at 5 o'clock (27 and 3 11), the hour and minute hands coincide again.

That is, Master Wang worked for 3 hours (16 and 4 11).

2.Looking at the watch from the mirror is 6:20, that is, the real time is 5:40 (you can draw a table pointing to 6:20 on a piece of paper, and then look at the back of the paper, and the 5:40 you see is the real time), so Xiao Ming ran for 40 minutes.

After 50 o'clock, the minute and hour hands were 180° in a straight line for the first time, at 9:15 a.m.

At 9 o'clock x minute, the minute hand is 180° to the hour hand.

Hour hand position: 45+1 12*x

Position of the minute hand: x

That is, 45 + 1 12 * x = 30 + x

The solution is x=16 and 4 11.

That is, after 26 and 4 11 minutes, the minute and hour hands are in a straight line for the first time.

4.The method of calculating the beginning of the minute hand and the hour hand is exactly the same as the third problem, and the method is the same as the first problem when the end coincides.

Between 11 o'clock and 11 o'clock, when the minute hand and the hour hand are at 180°, the time is a little more than 10:20 a.m., the method is the same as in question 3.

6.Except for 2 o'clock and 8 o'clock, which are only at right angles once, there are 2 right angles every hour, that is, (12-2)*2+2=22 times.

The minute hand went one block and went 360 60 = 6 degrees, and the hour hand went 1 12 squares and walked 6*1 12 = degrees.

Solution: Obviously, the second hand first bisected the angle between the minute and hour hands after 1 minute.

If the second hand divides the angle between the minute hand and the hour hand for the first time, then the angle of the hour hand is degrees, the angle of the minute hand is 6x degrees, and the angle of the second hand is 360x degrees.

So there is: [The acute angle between the second hand and the 12 o'clock position is: 360x-360, which is half the angle between the minute hand and the hour hand plus the angle at which the hour hand travels.] )

Solution: x = 1440 1427 (points).

A: After 1440 to 1427 minutes, the second hand divides the angle between the minute and hour hands for the first time.

dFour times blind.

Easy to draw: sidebar.

The second hand is equal to the hour and minute hands twice (at about 3.08 seconds and 3:040 seconds), the second hand is equal to the minute hand, the second hand is once (at about 3:030 seconds), the minute hand is equal to the minute hand, and the second hand is once (at about 3:046 seconds).

The answer is hunger

It can be seen that the second hand moves the fastest.

There are two cases when the second hand is in the middle of the hole, there is one case when the minute hand is in the middle, and there is also one case when the hour hand is trembling back in the middle.

At the beginning, the second hand is rotated for about 7-8 seconds, and the second hand is sandwiched between the minute and hour hands.

When the second hand is turned for about 30 seconds, it is the third time, and the hour hand is in the middle of the second hand and minute hand.

The second hand turns to around 45 seconds for the fourth time, and the minute hand is in the second hand and the time of the hand is the sum of the hand.

The minute hand rotates 360 60 = 6 degrees per minute.

The hour hand, 360 (12 60) = degrees per minute.

00, when the minute hand lags behind, the slow base needle 8 12 360 = 240 degrees.

It takes for the minute hand to catch up with the hour hand: 240 (min.)

Departure time is 480 11 minutes after 8 am.

00 time, which is 2 12 360 = 60 degrees behind the hour hand.

When the minute hand is at a flat angle to the hour hand, the minute hand rotates more than the hour hand: 180 + 60 = 240 degrees.

Required: 240 (minutes.)

Arrival time is 11 minutes after 2:480 p.m.

Subtract it, and the time used by this god scumbag is 6 hours.

:00:00 Heavy Qing shirt time, Liang happened to be about 8:44 minutes.

At 00:00, when the hour hand is at a flat angle to the minute hand, it is about 1:33 p.m

Subtract the honorific keys to get 4 hours and 49 minutes.

At 8 o'clock, the distance between the hour hand and the minute hand is 8 * 5 = 40 divisions, the speed of the hour hand is 1 12 divisions per minute, and the speed of the minute hand is 1 square per minute.

40 (1-1 12) = 480 11 (min) The 2 o'clock minute hand is 10 divisions behind the hour hand, and the lead is 30 divisions (half a clock face) after forming a flat angle (10+30) (1-1 12) = 480 11 (minutes) for a total of 6 hours, seepage stupidity -480 11 minutes + 480 11 minutes = 6 hours + 120 11 minutes = 6 hours.

Leisurely as spring with the right solution).

Set 8 9 to move x minutes when the bucket is at a flat angle.

x=120/11

2 3 Y minutes when moving at a flat angle.

y=480/11

So it takes 5 hours, add 360 to 11 minutes.

Hour hand 360° 12 = 30° 30° per hour 60 = per minute.

Minute hand 360° 60 = 6° per hour.

If the time is at a right angle, coming back or at a right angle, then it can be seen as walking time, the hour hand is wide, the angle of the hand should be 90°, and the hour hand and minute hand are dry at -90°, and the time x minute x is set to go for about 33 minutes.

I don't know if it's a hole, haha.

The angular velocity of the hour hand is minutes; The angular velocity of the minute hand is 6° Qiaohuai;

When going out at a right angle, it is still at a right angle when it comes back, and the liquid source indicates that the minute hand is behind and the hour hand is in front when going out.

When I came back, the minute hand was in front of the filial piety and buried in front of the friend, and the hour hand was behind.

Set the time to go out at x minutes.

then x=points).