Ten Daily Electronic Common Sense-Section 5

How to configure and modify the network of TQ2440 development board?

1. Modify the network configuration file /etc/net.Conf, which contains information such as IP address, mask, gateway, and mac value.
2. Modify /etc/nettype. conf file, which contains the type of network used. When CDMAUSE is 1, it means using GPRS or CDMA dial-up to access the Internet; when CDMAUSE is 0, and NETTYYPE is 1, it means using wired network, and DM9000 can access the Internet; when CDMAUSE is 0, and NETTYPE is 2, it means using wireless network and wireless network card to access the Internet .
3. Modify /etc/resolv. conf file, which contains DNS information. When using the TQ2440 to log in to the Internet, be sure to set the DNS value, which is provided by the local network provider.

What kind of external reset and which five internal resets does the Motorola MC68HC08 series microcontroller have?

• External Reset：The external reset of the MC68HC08 family is implemented by an external circuit inputting an active low level on the external reset pin RST.When the reset button switch is pressed, a reset can be implemented to cause the microcontroller to resume operation.
• Internal Reset：The five internal resets of the MC68HC08 series are Power-OnReset (POR), Watchdog (Computer Operating Properly, COP) counter overflow reset, Low-Voltage Inhibit (LVI) reset, illegal opcode ( Illegal Opcode, ILOP) reset, illegal address (Illegal Address, ILAD) reset. All of them will have the following effect: pull the RST pin low and hold it for 32 crystal oscillator cycles (CGMXCLK) so that the external device can get reset synchronously; release the RST pin after 32 crystal oscillator cycles, making it back high level, and then continue to maintain its internal reset state after delaying 32 crystal oscillation cycles, and then start executing the program from the reset vector.
  1. Power-on reset (POR) The microcontroller should be able to restart the program after it is powered on, so the power-on reset is the most commonly used reset method.
  2. Watchdog (COP) reset The watchdog module of the MC68HC08 series is an independent running counter that resets the system when the counter overflows. Because it plays the role of a real-time monitoring system, people give this module a more popular and more vivid name “watchdog”. The clock source of the watchdog counter is the output clock CGMXCLK of the crystal oscillator. In order to prevent the watchdog counter from overflowing and resetting, it must be considered to periodically clear the watchdog counter in advance by software during normal program execution to avoid it from overflowing. When the program cannot be executed normally, the watchdog counter cannot be cleared periodically, so the overflow will inevitably lead to reset, so that the program will resume normal operation. The system configures a control register COPCTL for the watchdog, whose address is $FFFF. The watchdog counter can be cleared by writing any value to the COPTCL register. In addition, the STOP instruction and internal reset source reset can also clear the watchdog counter. Whether the watchdog module works and its counter overflow cycle is determined by the COPD bit and the COPRS bit in the configuration register CONGIG1.
  3. Low-Voltage Inhibit (LVI) Reset A reset that occurs when the supply voltage falls below the lowest limit. Whether the LVI works and the limit value of the supply voltage are also determined by the relevant bits in the configuration register CONGIG1.
  4. Illegal Opcode (ILOP) Reset An internal reset caused by the execution of an illegal opcode that is not in the instruction set. It should be noted that if the system has been set to not execute the STOP instruction, executing this instruction will also cause an illegal opcode reset.
  5. Illegal Address (ILAD) Reset Internal reset caused by an access to an illegal address outside the addressing range while reading an opcode. But when storing data, accessing an illegal address will not generate a reset.

What kinds of libraries are commonly used in VHDL programming?

1. IEEE library
2. STD library
3. STD library

What is the role of the Logical Link Control Sublayer (LLC)?

Serving remote data requests and data transfers; determining which message is received by the LLC sublayer that is actually being used; providing means for recovery management and overload notification.Here, defining object processing is more free.

What are the precautions when using a capacitor to adjust the signal transition characteristics?

• If a slowed edge rate is acceptable, three times the calculated value c.. is generally used as the new upper limit.
• Select capacitors with the correct rated voltage and suitable material according to the usage environment.
• Note that the capacitors are all accurate, 80%/-0% deviation is acceptable for power supply filtering, but unacceptable for high-frequency signals.
• Install capacitors using the shortest possible pins and leads.
• Check whether the function of the circuit is affected by the installation of capacitors. Bulk capacitors can distort the signal excessively.

What is the address resolution protocol used for?

The Address Resolution Protocol (ARP) is used to translate IP addresses into hardware addresses to send frames to the next hop device or the final destination device.The ARP request is sent over the local network and asks which network interface has a specific IP address.The NIC with this IP address sends an ARP response containing its hardware address.

What are the main components of a typical IoT system?

Applications, middleware, network architecture, gateways, remote machine equipment.

What is the function of the reference voltage resistance grading circuit?

A signal voltage (such as a reference voltage) is divided into signal voltages of several voltage levels and applied to respective circuits.

What is the constant magnetic magnetoelectric sensor commonly used to measure?

Constant magnetic general-purpose magnetoelectric sensors are commonly used to measure vibration speed.

What are the main characteristics of pattern recognition of RFID data streams?

The speed of data processing must be faster than the arrival of data. To ensure the statistical significance of event patterns during event processing, there must be enough data, and the algorithm must be able to cope with the changes in the pattern.