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    What is the direction of power management technology for portable applications?

    Power management technologies for portable applications are moving towards higher efficiency, smaller size, and greater flexibility.
    New control schemes, fast control of power rails, and communication between digital processors and their analog power management components will all be enhanced as interface capabilities evolve.

    What are the two methods for clearing interrupt requests?

    1. Prefetching of interrupt vector: The interrupt vector is an address information. The retrieval of the address operand will generate an interrupt acknowledge signal to clear the interrupt request.
    2. Software clear: The software can generate an interrupt confirmation signal by writing a logic 1 to the ACKK bit of the keyboard status and control register INTKBSCR, and clear the interrupt request. Before exiting the interrupt service routine, write 1 to the ACKK bit to prevent spurious interrupts due to noise interference. And setting ACKK will not affect the subsequent transmission of other keyboard interrupt pin signals. A falling edge after the ACKK bit is set will generate another interrupt request. If the keyboard interrupt mask bit IMASKK has been cleared, the CPU will load the program counter with the interrupt vector addresses of $FFE0 and $FFEl. The software clear makes all the pins that cause the interrupt return to high level, that is, the keyboard interrupt request will be cleared after all the pins that cause the interrupt return to the high level. The keyboard interrupt remains set as long as any of the interrupt-enable pins is low. It should be noted that if MODEK=0, the falling edge is triggered, the prefetching of the interrupt vector or the software clearing can immediately clear the keyboard interrupt request. But if MODEK=1, the falling edge and low level are triggered, the prefetching or software clearing of the interrupt vector and all the pins that allow the keyboard interrupt function return to high level, can clear the keyboard interrupt. In order to determine the logic level on the keyboard interrupt pin, the data direction register can be used to set the pin as input and read the data register. The keyboard flag bit KEYF in the keyboard status and control registers is used to determine whether there is a pending interrupt. The KEYF bit does not affect the keyboard interrupt mask bit IMASKK.

    What are the main components of the server-side main menu interface design?

    The server-side main menu interface design involves three components, namely dialog, list and menuedit.
    The list class mainly implements the menu list in the main menu management interface.
    The dialog class mainly implements the addition of dishes.
    menuedit contains two graphical interface construction classes, dialog and list.
    It constitutes the server-side operation interface, as well as some other operations (database modification, data transmission).
    These three classes contain the static global variable allusers in ThAccept and the function that sends database operation instructions to the client.

    What is the command designed in SC()S?

    1. File processing commands: create files, select files and delete files.
    2. Security management commands: take password (take random number), internal authentication, external authentication and verification password (PIN and ISC).
    3. Application commands: read binary, write binary, read record and write record. Among them, the create file command can only be executed before the card is personalized.

    What are the main indicators of the static characteristics of the sensor?

    • Linearity (non-linear error)
    • Sensitivity
    • Accuracy (precision)
    • Minimum detection amount and resolution
    • Hysteresis
    • Repeatability
    • Zero drift
    • Temperature drift

    What is the difference between nominal power and power consumption?

    Nominal power and power consumption are two different concepts. For example, connect a 10Q, 15W resistor to both ends of a 100V DC power supply.
    It can be calculated that the current flowing through will reach 10A, and it can also be calculated that the power consumption generated when the current of 10A is turned on will be as high as 1000W. This is much more than the 15W thermal power (nominal power) that the resistor itself can handle and will surely burn out quickly.  
    The power consumption is the power consumption that is allowed to generate thermal power when the resistor is operating. For example, add 10V DC voltage to a 10Q, 15W resistor, the current flowing through it is 1A, and the generated thermal power is 10W.
    The thermal power is within the 15W (nominal power) that the resistor can withstand, and the resistor will not be burned, and the generated l0W thermal power can be said to be its actual power consumption. If the current flowing through the resistor is 0.5A, it will generate 5W of thermal power, which is also its actual power consumption.
    Therefore, within the nominal power of the resistor, the greater the current flowing, the greater the power consumption. The smaller the current flowing, the smaller the power consumption. If the thermal power generated by the current flowing through the resistor is greater than its nominal power, the resistor is bound to burn out.

    What is the resonance type magnetostrictive detonation sensor?

    The resonant magnetostrictive detonation sensor is mainly composed of an induction coil, a telescopic rod, a permanent magnet and a shell.

    Two cells that do not interfere with each other can use the same frequency.What kind of co-frequency cells can interfere with each other?

    1. Wireless system that supports co-frequency networking: WCDMA is a broadband wireless system, which can bury useful signals in interference, and at the same time, can extract useful signals from interference. These interferences can be interference from other users in the cell, or interference from other adjacent cells. The interference caused by the use of the same frequency in the adjacent cell and this cell can be completely overcome by the WCDMA standard.
    2. Cells separated by a certain distance: The path loss of radio waves increases with the increase of the path. When two cells are far enough apart, the mutual influence between cells using the same frequency can be ignored. This sufficiently far distance is called the co-frequency multiplexing distance.
    3. Cells with sufficient isolation: when the blocking loss between the two cells is large enough, or the wall penetration loss is large enough. When there is no overlapping area or very little overlapping area between two cells, the two cells can be set to the same frequency. Frequency planning is to allocate corresponding frequency resources according to coverage and traffic distribution in cells that cannot use the same frequency. Frequency allocation process to avoid co-channel interference and improve network performance.

    What are the photoelectric effects usually divided into several categories?

    The photoelectric effect is usually divided into two categories: external photoelectric effect and internal photoelectric effect.

    What is a parallel interface?

    Parallel port for short, that is, LPT interface, is an extended interface using a parallel communication protocol.
    The data transfer rate of the parallel port is 8 times faster than that of the serial port, and the data transfer rate of the standard parallel port is 1Mbps, which is generally used to connect printers, scanners, etc. So the parallel port is also called the print port.
    In addition, both the serial port and the parallel port can realize dual-machine interconnection through direct cable connection, in which data can only be transmitted at low speed. The function and structure of serial port and parallel port of PC have not changed much over the years.
    When using serial and parallel ports, in principle, each peripheral must be plugged into one port. If all the interfaces are used, the interface can only be added by adding plug-in cards. The serial and parallel ports are not only limited in speed, but also very inconvenient to use, for example, they do not support hot swapping.
    With the popularity of the USB interface, it is rarely used at present, and with the promotion of the BTX specification, it will inevitably be eliminated. The parallel port uses a 25-pin double-row socket. In addition to the most common use in printers, it can also be used to connect scanners, ZIP drives, and even external network cards, tape drives, and some extended hard drives.
    Let’s take a brief look at the development history of the parallel port: the initial design of the parallel port is to transmit data in one direction, that is to say, the data can only be input or output at a certain time. Later, IBM developed a bidirectional parallel port technology called SPP (StandardParallelPort), which can realize the simultaneous input and output of data. This turns the original semi-interactive parallel port into a real two-way interactive parallel port.
    Intel, Xircom and Zenith jointly launched EPP (EnhancedParallelPort, enhanced parallel port) in 1991, which allows the transmission of larger-capacity data (500- 1000byte/s). It is mainly aimed at non-printer devices that require higher data transmission speed, such as storage devices.
    Following the introduction of EPP, in 1992 Microsoft and Hewlett-Packard jointly launched a new parallel port standard called ECP (ExtendedCapabilitiesPort,). Unlike EPP, ECP is a standard developed specifically for printers. IEEE1284, released in 1994, covers both EPP and ECP standards. But the operating system and hardware are required to support the standard, which is no longer a problem for today’s hardware. At present, the parallel ports we use all support the two standards of EPP and ECP, and we can set the working mode of the parallel port by ourselves in the CMOS.


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