You are an embedded hardware engineer and embedded software engineer with 20 years of experience, as well as a computer scientist. Please provide detailed answers from a beginner’s perspective, keeping my requirements in mind, and answer everything at once:
1. What are the commonly used microcontrollers in embedded systems?
2. What is an MCU? What is the core difference between it and a CPU?
3. What does “real-time performance” mean in embedded systems?
4. Where is the program for the 51 microcontroller usually stored?
5. What is the main function of RAM in embedded systems?
6. What is GPIO? What is its most basic function?
7. In serial communication (UART), what does “baud rate” mean?
8. What are the names of the two signal lines in I2C communication?
9. How many signal lines are typically required for SPI communication? What are they?
10. What is the role of “interrupts” in embedded systems?
11. Can the interrupt priority of the 51 microcontroller be set manually?
12. What is a timer/counter? What are its common uses in embedded systems?
13. What are the commonly used power supply voltages in embedded systems? (List at least 2 types)
14. What is the function of an A/D converter? What signal does it convert to what signal?
15. Is the function of a D/A converter the opposite of that of an A/D converter? Why?
16. In embedded program development, what does “cross-compilation” mean?
17. What is the main function of the JTAG interface when debugging embedded programs?
18. What is “bare-metal programming”? How does it differ from OS-based programming?
19. What are the commonly used real-time operating systems (RTOS) in embedded systems? (List at least 2 types)
20. What is the relationship between the crystal oscillator frequency of a microcontroller and the instruction execution speed?
21. Why do GPIO pins need pull-up or pull-down resistors?
22. What are the functions of the “start bit” and “stop bit” in serial communication?
23. How many bits is the address of a slave device in I2C communication?
24. What does “master-slave mode” mean in SPI communication?
25. Why should the execution time of interrupt service functions be kept as short as possible?
26. What parameters are related to the “timing time” of a timer?
27. What are the characteristics of Flash memory in embedded systems? (Compared to RAM)
28. What is a “watchdog timer (WDT)”? What is its main function?
29. What is the difference between “level-triggered interrupts” and “edge-triggered interrupts” in embedded systems?
30. What are the commonly used embedded programming languages? What are their respective advantages?
31. Why does the P0 port of the 51 microcontroller usually require an external pull-up resistor?
32. What is the function of the “parity bit” in serial communication?
33. What problem does “bus arbitration” solve in I2C communication?
34. What do “clock polarity (CPOL)” and “clock phase (CPHA)” refer to in SPI communication?
35. What is “interrupt nesting”? Do all embedded systems support interrupt nesting?
36. What is the difference between the “counting mode” and the “timing mode” of a timer?
37. How is “power loss protection” typically implemented in embedded systems?
38. What is “PWM (Pulse Width Modulation)”? What are its applications in embedded systems?
39. What hardware conditions are usually required when downloading embedded programs to an MCU?
40. What is “memory-mapped I/O”? Why is this method commonly used in embedded systems?
41. What architecture do STM32 series MCUs belong to?
42. What are the common values for “data bits” in serial communication? (List at least 2 types)
43. What is the maximum transmission rate of I2C communication?
44. Why is SPI communication faster than I2C communication?
45. Can other functions be called within an interrupt service function? What should be noted?
46. What event occurs when a timer overflows? How is this event handled?
47. What is the function of “EEPROM” in embedded systems? How does it differ from Flash?
48. What is the “resolution of an ADC”? What are the advantages of higher resolution?
49. What are the differences between “debuggers” and “programmers” in embedded development?
50. What is “task scheduling”? What is one of the core functions of an RTOS?
51. Where is the stack of the 8051 microcontroller usually set?
52. What are the common values for “stop bits” in serial communication? (List at least 2 types)
53. In I2C communication, who sends the “ACK (acknowledgment bit)”?
54. Who provides the clock for the master and slave devices in SPI communication?
55. What is “interrupt masking”? How is it implemented?
56. What is the function of the “prescaler” in a timer?
57. What is the purpose of “power management” in embedded systems? What are the common low-power modes?
58. What does the “duty cycle” of PWM refer to? What does a duty cycle of 50% indicate?
59. What are the main tasks performed by the “startup file” of an embedded program?
60. What is the role of “task priority” in RTOS? How does a high-priority task affect low-priority tasks?
61. What is the function of the “reset circuit” in a microcontroller? What are the common reset methods?
62. If the baud rate is 9600 in serial communication, how many bytes of data can be transmitted per second (assuming 8 data bits, 1 stop bit, no parity)?
(Assuming 8 data bits, 1 stop bit, no parity)?
63. Can multiple master devices be connected to a single I2C bus?
64. What is the difference between “full duplex” and “half duplex” in SPI communication?
65. What is an “external interrupt”? How does it differ from the trigger source of a timer interrupt?
66. What is the function of the “capture mode” in a timer? What are the common application scenarios?
67. What is the typical erase unit of “Flash” in embedded systems? (Page/Byte/Word)
68. What does the “sampling rate” of an ADC refer to? Is a higher sampling rate always better?
69. Why can’t the “printf function” be used directly in bare-metal programs? How can this be resolved?
70. What problem do “semaphores” in RTOS mainly solve?
71. Are the working modes of Timer 0 and Timer 1 in the 51 microcontroller completely the same?
72. What is the function of “flow control” in serial communication? What are the common flow control methods?
73. In I2C communication, when can the “SDA (data line)” be pulled low?
74. What is the function of the “chip select signal (CS)” in SPI communication?
75. Is the entry address of an interrupt service function fixed? Why?
76. What are the advantages of the “auto-reload mode” of a timer?
77. What problems can “electromagnetic interference (EMI)” cause in embedded systems? How can EMI be reduced?
78. What is the relationship between the “frequency” and the period of PWM? What are the effects of higher frequency on the load?
79. What are the differences in storage locations between “global variables” and “local variables” in embedded programs?
80. What is the role of the “task stack” in RTOS? What problems can arise if the stack size is set too large?
81. What working modes can the GPIO pins of STM32 be configured to? (List at least 2 types)
82. What are the possible reasons for data transmission errors in serial communication? (List at least 2 types)
83. What are the level changes of the “start condition (S)” and “stop condition (P)” in I2C communication?
84. How can a specific slave device be selected when multiple slave devices share a single SPI bus?
85. What is “interrupt response time”? What parts does it consist of?
86. What is the function of the “compare mode” in a timer? What are the common application scenarios?
87. What circuit protection is typically required for “lithium battery power supply” in embedded systems?
88. How does the “reference voltage” of an ADC affect the conversion results? What happens if the reference voltage is unstable?
89. What are the differences between “online debugging (ICP)” and “offline debugging” in embedded development?
90. What scenarios are “message queues” in RTOS mainly used for?
91. What is the “clock tree” of a microcontroller? What is its function?
92. What is the core difference between “asynchronous communication” and “synchronous communication” in serial communication?
93. What does the master device typically do if the slave device does not respond (ACK) in I2C communication?
94. In SPI communication, what is the data transmission order, high bit first or low bit first? Can it be configured?
95. What is a “pseudo-interrupt”? How can its occurrence be avoided?
96. What is the function of the “gated mode” in a timer?
97. What is the reason for “key debounce” in embedded systems? What are the common debounce methods?
98. Can PWM signals directly drive high-power motors?