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  • Ten Daily Electronic Common Sense-Section 137

    What are the main technical features of the MAX7316?

    1. 400kbit/s, 2-wire serial interface, 5.5V voltage tolerance;
    2. Working voltage is 2~3.6V;
    3. 8-bit PWM white LED brightness control, global 16-level brightness control, additional l6-level independent brightness control;
    4. Two Phase white LED flashes;
    5. 5.5V input over-voltage protection, input clears serial port status, restores to power-on default state;
    6. High port output current, 50mA (maximum value) per port, output rated voltage 5.5V, open-drain ;
    7. Transient detection with interrupt output;
    8. Low standby current typical value 1.2.

    What are the VHDL data objects of the combined circuit?

    1. Constant
    2. Signal
    3. Variable

    What is a CRC operation?

    CRC (Cyclic Redundancy Check) operation detects errors in data blocks.
    The single-chip microcomputer uses CRC. The CCITT polynomial (X16 X12 X5 1) generates a CRC check code. the
    The CRC code is a 16-bit code generated for a block of arbitrary data length in units of 8 bits.
    After setting the initial value to the CRCD register, whenever 1 byte of data is written to the CRCIN register, the CRC code is set to the CRCD register. For the data of l byte, the generation of CRC code needs 2 cycles.

    In the NSPW strategy, which stages are the injection phases divided into?

    First, an adaptive method is proposed to dynamically select nodes with superior performance.
    This method is not only conducive to distributing message copies as soon as possible, but also increases the possibility of message transmission to the destination node.
    Second, we calculate the number of message replicas that should be forwarded to the next-hop node. Those nodes with high activity will be assigned more copies of messages.

    What are the characteristics of the selective process program?

    • The selective process program with 3 branches has the following characteristics:
      1. Which process to choose to execute from the 3 processes is determined by the transition conditions X0, X10, and X20.
      2. Branch transfer conditions X0, X10,) (20 cannot be connected simultaneously, whichever is connected first, which branch is executed.
      3. When S20 has acted, once x0 is connected, the program transfers to S21, and then $20 is reset Therefore, even if X10 or X20 is turned on later, S31 or S41 will not act.
      4. Convergence state S50 can be driven by any one of S22, S32, and S42.

    Which two types of sensors are calibrated?

    There are two types of sensor calibration: static calibration and dynamic calibration.

    What are the characteristics of microwave RFID antennas?

    Various structures, suitable for pasting on the surface of various objects. Many are mass-produced on strips, and the size of the electronic tags composed of antennas and chips is very small, providing expandable devices.

    Compared with ordinary video coding, what is the main feature of SVC video coding with F?

    1. With scalable video streams, it can dynamically adapt to changes in network bandwidth. The reconstruction quality has an approximately linear relationship with the j pedicle width.
    2. It has strong robustness against data loss.
    3. It can meet the needs of user terminals with different processing capabilities at the same time.

    What are the three major categories of electrolytes for electric double layer capacitors?

    1. Water system;
    2. Salt soluble in organic solution system;
    3. Ionic liquids (ILs).

    Characteristics and applications of infrared light-emitting diodes

    Infrared remote controllers have been widely used in color TVs, audio systems and various household appliances.
    The control distance of the remote control can generally reach 6-8 meters, which is very convenient to use. Because of the large amount of infrared remote control, its infrared transmitting and receiving circuits have complete supporting devices. These devices are not only low in price but also reliable, and the circuit is extremely simple.
    Electronic enthusiasts can use these devices to assemble remote controls for various purposes, which is not only practical but also can increase the interest of making.
    The characteristics of infrared light-emitting diodes Infrared is invisible light, which is imperceptible to the human eye. In electronic technology, infrared light-emitting diodes (also known as infrared emitting diodes) are used to generate infrared rays.
    Commonly used infrared light-emitting diodes (such as SE303•PH303) are similar in appearance to light-emitting diodes (LEDs). The transistor BG is used as a switch, and when a drive signal is applied to the base, the BG transistor is saturated and turned on. The infrared light-emitting tube D is also conducting forward work and emitting infrared light (near infrared rays are about 0.93 μm). The tube voltage drop of D is about 1.4V, and the working current is generally less than 20mA. In order to adapt to different working voltages, R2 is often connected in series in the circuit of D as the current limiting resistor of D. In order to increase the control distance of infrared rays, the infrared light-emitting diode D should work in a pulsed state, that is, the working current is pulsating.
    Because the effective transmission distance of pulsating light (modulated light) is directly proportional to the peak current of the pulse, it is only necessary to increase the peak current Ip as much as possible to increase the transmission distance of infrared light.
    The way to improve Ip is to reduce the pulse duty cycle, that is, to compress the pulse width τ. For some color TV infrared remote controllers, the working pulse duty ratio of the infrared light-emitting tube is about 1/4 to 1/3. Some infrared remote controls for electrical products have a duty cycle of 1/10. Reducing the pulse duty cycle can also greatly increase the emission distance of low-power infrared light-emitting diodes.
    The power of common infrared light-emitting diodes is divided into three categories: low power (1mW ~ 10mW), medium power (20mW ~ 50mW) and high power (50mW ~ 100mW or more). When using infrared light-emitting diodes with different powers, corresponding power drive tubes should be configured.
    When infrared light-emitting diodes are used to emit infrared rays to control the controlled device, there are corresponding infrared light-to-electricity conversion elements in the controlled device, such as infrared receiving diodes, photoelectric transistors, etc.
    In practice, there are paired diodes for infrared emission and reception, which are cheap and easy to use, such as PH303/PH302.
    There are two ways to emit and receive infrared rays, one is direct and the other is reflective.
    The direct type means that the luminous tube and the receiving tube are relatively placed at the two ends of the transmitter and the controlled object, with a certain distance in the middle.
    The reflective type means that the luminous tube and the receiving tube are juxtaposed together, and the receiving tube is always without light. Only when the infrared light emitted by the luminous tube encounters a reflector, the receiving tube receives the reflected infrared to work.


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