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  • Ten Daily Electronic Common Sense-Section 26

    What is the L2CAP Resource Manager?

    The L2CAP resource manager module is responsible for managing and ordering PDU segments, supporting inter-channel scheduling functions, and ensuring that L2CAP channels with QoS guarantees will not be denied access by physical channels due to exhaustion of controller resources. This feature is necessary due to the limited cache of the controller and the limited hardware bandwidth of the HCl.

    What are the main factors causing electromagnetic interference?

    1. Electromagnetic interference generated by switching circuit
    2. Electromagnetic interference generated by diode rectifier circuit
    3. Relationship between dv/dt and load size

    What is the role of Interface Management Logic (IML)?

    The interface management logic interprets the commands from the CPU, realizes the addressing of CAN registers, and provides interrupt information and CAN controller status information to the CPU.

    What are the two basic requirements for sensor characteristics for biomedical measurements?

    • There are two basic requirements for the characteristics of the sensor:
      1. When the input is zero, the output is also required to be zero;
      2. For a certain input value, the output value is also determined according to the corresponding relationship.

    What is the role of buffering?

    The MC68HC08 series provides two output comparison functions with buffering and without buffering, and the output comparison function without buffering is the same as that of the MC68HC05 series.

    The disadvantage of this output comparison is that when the next output comparison signal needs to be changed, the new preset value must be written into the channel register in advance, which naturally takes a certain amount of time, resulting in the minimum time between two output comparisons.

    The interval is then limited by rewrite operations. It can be seen that the output comparison without buffering is only suitable for occasions where the time change requirement is not too fast, and the duty cycle of the pulse cannot be too small. This defect can be overcome by adding a level of buffering. A buffered output compare uses two channels of the same timer, one for the output compare and the other for writing the new compare value, switching alternately. MC68HC908GP32 uses TCHl as buffer, realizes comparison output by TCH0 pin, and TCHl pin can also be used as ordinary I/ 0 pin.

    When using the buffered output compare function, you must set the MSOB bit of the timer channel 0 status and control registers during initialization, and also write the comparison setting value to the 1 channel register.

    When a timer overflow occurs, channel 1 obtains the output control right of the TCH0 pin, and a new comparison value can be written to channel 0 at this time, so the two channels jointly control the output of TCH0.

    Figure 4.4 depicts this alternate-master-auxiliary output comparison structure. There is also a special case that if the pulse period is exactly equal to the overflow period of the timer counter, and the overflow flip control flag TOVx is set, then the output comparison module flips the output level once when a comparison occurs, and the count value overflows.

    It will automatically flip the output level once again. This cycle realizes the continuous output of the periodic waveform. The following is an example to deepen the understanding of the use of this output comparison function.

    What are the commonly used antennas for RFID systems?

    Symmetrical resonator antennas, microstrip antennas, antenna arrays and some other types of antennas.

    What is the inverse piezoelectric effect?

    This phenomenon, which is converted into mechanical effect or from electrical energy into mechanical energy due to electrical effect, is the inverse piezoelectric effect.

    What are the factors that determine the battery pack configuration?

    Factors that determine battery pack configuration are: minimum, maximum, and nominal voltage values, charge current, discharge current, and charge capacity to meet operating requirements.

    Where is the control law accelerator library installed by default?


    What are the main features of the IC card attendance management system?

    1. Accurately record the time and date of each employee’s get off work and work.
    2. The number of employees allowed to be recorded should meet the requirements of the attendance unit.
    3. Allow 24 hours of continuous work.
    4. It can continue to work after the power is cut off.
    5. There is a query function.
    6. Set a password for the management system to ensure security.


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