Briefly describe the basic use of VIC?
- Determine whether the interrupt is assigned as a FIQ or an IRQ interrupt.
- If the allocation is FIQ, perform the relevant initialization; if the allocation is IRQ, continue to allocate whether it is a vector IRQ or a non-vector IRQ interrupt, and then perform the relevant settings respectively.
- Clear the corresponding interrupt flag and enable the corresponding interrupt.
- Write an interrupt service routine.
What is the working principle of the digital accelerometer ADXL345?
The ADXL345 is a complete three-axis acceleration measurement system with selectable measurement ranges of ±2 g, ±4 g, ±8 g or ±16 g. Both dynamic acceleration due to motion or shock can be measured, as well as static acceleration. Gravitational acceleration, for example, allows the device to be used as a tilt sensor. The sensor is a polysilicon surface micro-machined structure placed on top of the wafer. Due to the applied acceleration, multi-product silicon springs are suspended above the structures on the wafer surface, providing force resistance. The differential capacitor consists of a separate stationary plate and a moving mass connecting plate, which enables the measurement of the deflection of the structure. The acceleration deflects the inertial mass and unbalances the differential capacitance, so that the magnitude of the sensor output is proportional to the acceleration. Phase sensitive demodulation is used to determine the magnitude and polarity of the acceleration.
What is the charging process of the TWL2213 lithium-ion battery charger for a single-cell lithium-ion battery?
- Wake-up of Li-ion battery pack
- Pre-charge
- Fast charge and termination
- Temperature monitoring
What are the two interfaces?
- Serial interface: The transmission of one bit of data at a time is called serial, and the interface used for serial communication is called serial interface. The serial interface consists of three parts: receiver, transmitter and controller. The receiver converts the serial data sent by the external device into parallel data and sends it to the data bus. The transmitter converts the parallel data on the data bus into serial data and sends it to the external device. The controller is a circuit that controls the above two transformation processes. The main purpose of the serial interface is to perform serial/parallel and parallel/serial conversion.
- Parallel interface: The simultaneous transmission of two or more data is called parallel. It transmits various data, such as 8-bit data, at the same time. Almost all of the microcontrollers use parallel transmission. Due to the different speeds of the CPU and peripherals, the data lines of the peripherals cannot be directly connected to the bus. In order to match the actions of the CPU and peripherals, buffers and latches are needed in the middle to temporarily hold data. A circuit with these functions is called a parallel interface. Parallel and serial interfaces are collectively referred to as input/output ports.
What is a spontaneous chemical reaction?
A chemical reaction moves toward a kinetic equilibrium state. In equilibrium, both reactants and products are present and there is no further tendency to produce a net change.
The WirelessHART standard uses multiple multiplexing techniques to ensure that its communications have high reliability？
- Time division multiplexing: All non-broadcast messages require the receiver to acknowledge them in the same time slot. When the transmission fails, the retransmission mechanism will be activated.
- Space (path) multiplexing: The topology of the WirelessHART network is meshed. Each pair of end-to-end communications must have more than two paths available.
- Frequency reuse: The WirelessHART standard provides a channel hopping technology based on 16 channels.
- Coding and polarity: The WirelessHART standard adopts the IEEE 802.15.4 standard, and the coding and modulation mode of the IEEE802.15.4 standard is reasonable and reliable. We expect it to be further enhanced in future releases.
What is the composition of the RFID antenna?
Electric fundamental oscillators and magnetic fundamental oscillators.
What are the advantages and disadvantages of Hall sensor?
Although the Hall sensor has the disadvantages of low conversion efficiency and large temperature influence. However, it has the advantages of simple structure, small size, firmness, wide frequency response, large dynamic range, no contact, long service life, high reliability, easy miniaturization and integrated circuitization. Therefore, it has been widely used in measurement technology, automation technology and information processing.
How is the conversion accuracy of the A/D converter defined?
The conversion accuracy of A/D converter is defined as the difference between an actual A/D converter and an ideal A/D converter on the quantized value. It can be expressed as absolute error or relative error.
What is the pyroeletric effect?
Certain crystals undergo electrical polarization when temperature changes. When the crystal is heated uniformly, equal and opposite charges are generated in certain directions of the crystal. When cooling a crystal, the change in charge is opposite to when heating it. This phenomenon is called the pyroeletric effect.
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