1. How Long Will 8-bit Microcontrollers Last!
Answer: Currently, the main focus of MCU products is still in the 8-bit domain, mainly applied in six major markets: automotive applications, consumer electronics, computer and PC peripherals, telecommunications, office automation, and industrial control. The automotive market is mainly in Europe and America, while the Asia-Pacific region is dominated by consumer electronics, with high volume and low price being the mainstream products. Currently, there is still a significant price difference between 16-bit MCUs and 8-bit products, and new application fields are still being developed. The industry expects that at least until 2005, 8-bit MCUs will remain the mainstream of MCU products.
2. Is Learning ARM and Embedded Systems More Promising Than Learning Other General Microcontrollers? What Related Knowledge Should a Beginner Have?
Answer: Generally, there is a hierarchical difference between 8-bit microcontrollers and ARM-based embedded systems. ARM is suitable for more complex high-end products, such as PDAs and mobile phones. In contrast, 8-bit microcontrollers, due to their simple architecture and relatively fewer hardware resources, are suitable for general industrial control and consumer appliances. For a beginner in microcontroller programming, it is recommended to start with HOLTEK series or 8051 type 8-bit microcontrollers for practice. Additionally, beginners should have knowledge of software programming, as microcontroller software programming is primarily based on assembly language, with each manufacturer having its own syntax, but mostly based on RISC (Reduced Instruction Set Computer) architecture, where all MCU instructions are composed of simple instructions. These simple instructions allow the MCU’s circuits to be optimized, thereby improving execution speed. Furthermore, beginners should possess knowledge about the application of microcontroller I/O interfaces, which involves the use of peripheral circuits and various components, and should be integrated with their studies in electronics and circuit theory.
3. What 8-bit Microcontrollers Comply with 44PIN of the 80 Series?
Answer: The 8-bit microcontrollers that comply with the 44PIN of the 80 series include Z8674312FSC, Z86E2112FSC, and Z86E2116FSC.
4. Please Introduce the Testing Methods for MCUs.
Answer: MCUs undergo different testing methods at each stage from production to packaging and shipment, mainly categorized into two types: mid-testing and final testing.
Mid-testing refers to WAFER testing, which includes functional verification and AC/DC testing. There are many projects, with the main ones for HOLTEK products as follows:
Continuity Testing: Checks whether each I/O pin’s protective diodes are functioning correctly.
Functional Testing: Loads the test data (TEST PATTERN) provided by the product designer into the IC and checks whether the results match the simulation status at that time.
STANDBY Current Testing: Measures the leakage current when the IC is in HALT mode, ensuring that each pin (PAD) remains unchanged in state 1, 0, or Z, and meets the minimum specifications.
Power Consumption Testing: Measures the static and dynamic power consumption of the entire IC.
Input Voltage Testing: Measures the input voltage response characteristics of each input pin.
Output Voltage Testing: Measures the output voltage levels of each output pin.
Related Frequency Characteristics (AC) Testing: Also involves applying a certain frequency externally to check whether the output matches it from the I/O ports.
To ensure the long-term and stable quality of IC production, reliability testing is also conducted, including ESD testing, LATCH UP testing, temperature cycling testing, high-temperature storage testing, humidity storage testing, etc.
Final testing occurs after the product is packaged, known as PACKAGE testing. This involves testing all products that passed mid-testing after packaging, primarily through automated machine testing, but the testing items remain the same as WAFER TEST. The purpose of PACKAGE TEST is to determine whether there is any damage to the IC during the packaging process.
5. Can a Microcontroller Be Used to Detect the Charging and Discharging Time of a Mobile Phone Battery and the Voltage and Current Changes During Charging and Discharging, and Use an I/O Port to Display the Results on a Computer?
Answer: Currently, most smart chargers on the market use MCUs to control charging current and voltage. As for displaying on a computer, it seems impractical; it might only be used in specialized battery testing instruments. For general mobile phone users, who would need to use a computer to display while charging? To achieve connection between the microcontroller and the computer, the simplest way is to use serial communication, but an RS-232 chip is required.
6. How Should One Approach ARM Programming?
Answer: Taking the concept of embedded systems as an example, embedded processors can generally be divided into three categories: embedded microprocessors, embedded microcontrollers, and embedded DSP (Digital Signal Processor).
Embedded microprocessors correspond to the CPUs of general-purpose computers. In applications, microprocessors are usually assembled on specially designed circuit boards, with the motherboard retaining only the functions related to embedded systems, thus meeting the requirements of small size and low power consumption. Current embedded processors mainly include: PowerPC, Motorola 68000, ARM series, etc.
Embedded microcontrollers, also known as microcontrollers, package the CPU, memory (a small amount of RAM, ROM, or both), and other I/O interfaces in a single integrated circuit. Common examples include HOLTEK MCU series, Microchip MCU series, and 8051, among others.
Embedded DSP is specifically used for fast processing calculations on discrete time signals, improving compilation efficiency and execution speed. DSP is increasingly entering the embedded market in fields such as digital filtering, FFT (Fast Fourier Transform), spectral analysis, and image processing.
7. In RF Control, What Other Methods Can Reduce the Radiation of the MCU’s Clock (Crystal Oscillator) and Data Lines, Besides Layout and Choosing Low-Radiation MCUs?
Answer: When designing high-frequency circuits, there are many considerations, especially for GHz-level high-frequency circuits, where the lengths of the electronic components’ pads and printed patterns significantly impact circuit characteristics. In recent years, there has been an increasing trend of high-frequency circuits sharing the same circuit board with digital circuits, forming what is known as mixed-load circuit systems. Such designs often lead to instability in high-frequency circuits when digital circuits operate, one reason being that noise generated by digital circuits affects the normal operation of high-frequency circuits. To avoid the aforementioned problems, in addition to separating the two circuit blocks, thoroughly reviewing the design concept before designing the circuit board is fundamental. Essentially, designing high-frequency circuit boards must adhere to the following three principles:
High quality.
Avoid shortcuts.
Avoid rushing for time.
The following are some suggestions for designing high-frequency circuit boards:
(1) The length of printed patterns affects circuit characteristics. Especially for transmission lines in GHz-speed digital circuits, strip lines are typically used, and by adjusting the wiring length, transmission delay time can be corrected, which also implies that the positioning of electronic components has a decisive impact on circuit characteristics.
(2) Make the ground better. The copper foil surface should be set as a ground layer, and the better ground connected via is a common feature of high-frequency circuit boards and high-speed digital circuit boards. Furthermore, it is crucial to avoid using narrow printed patterns to depict ground on high-frequency circuit boards.
(3) The ground terminal of electronic components should connect to the circuit board ground with the shortest length. Specifically, this can be achieved by placing vias near the electronic component’s ground terminal pad, allowing the electronic component to connect to the circuit board ground with the shortest length.
(4) Shorten signal line designs. Do not arbitrarily increase the wiring length; try to minimize the wiring length.
(5) Reduce coupling between circuits. Particularly, circuit separation between filters and amplifiers’ inputs and outputs is crucial, similar to cross-talk countermeasures in audio circuits.
(6) MCU circuit layout considerations: The oscillator circuit should only be close to the IC oscillator pins; maintain sufficient distance between the oscillator circuit and VDD & VSS; when the oscillation frequency exceeds 1MHz, no osc1 & osc2 capacitors are needed; the power and ground should be positioned as short as possible and ideally have equal width and spacing lines, with 104/103/102 ceramic capacitors added at node positions.
8. What Considerations Are There When Developing Systems with Intel’s 96 Microcontroller 80C196KB?
Answer: The software of a real-time system consists of a real-time operating system and application programs. The interface between the application program and the operating system is achieved through system calls. An MCU using the 80C196KB operating system can only use internal RAM as TCB and all system memory (including various control tables) and the working and data units of each task. Therefore, the following points must be noted:
(1) Allocate a separate stack area for each task, which serves as both the working unit of the task and the protection unit of the task control block.
(2) The task control block of the system only stores the stack pointers of each task, while the status of the tasks is stored in the task stack. When a task exits, its state is pushed onto the stack via an interrupt, and its stack pointer is saved in the system’s TCB; then, the stack pointer of the highest priority ready task is retrieved and sent to SP; finally, the interrupt return instruction is executed to switch to the new task.
(3) Try to implement the data and working units of each task using stacks, allowing tasks to use the same subroutine. Using stacks for parameter passing and as working units, instead of using absolute addresses in RAM, can achieve reentrant subroutines that can be called by various tasks and allow for recursive calls.
9. When Sampling Voltage on a Demo Board, the Results Are Unstable and Fluctuating; How Can This Be Eliminated?
Answer: Generally, simulators operate in a stable environment (usually 5V). If using the simulator’s A/D, it is essential to note whether its A/D reference voltage is provided internally by the simulator or needs to be supplied externally. A/D conversion requires a continuous clock cycle, so during simulation, the single-step debugging method should not be used, as it may lead to inaccurate A/D sampling values. To stabilize A/D sampling, a capacitor can be added to the A/D input to act as a filter; during software processing, median filtering methods can be adopted.
10. In a Car DVD System, How to Design an Electronic Anti-Shock System?
Answer: In a car DVD system, it is best to choose a high-end DVD player, as high-end DVD players usually employ electronic anti-shock systems (ADVANCEDESP). When the reading in the memory buffer decreases, the advanced electronic anti-shock design will read at double the normal speed to reduce noise, thus avoiding skipping even with continuous vibrations. Now, let me explain what electronic anti-shock is. Simply put, electronic anti-shock is a signal storage-release process. First, the CD must read the signal in advance, which is what we see as the machine accelerating, and then store the signal in RAM. When we turn on anti-shock, the sound we hear is the sound processed through RAM. This is the process. When there is no anti-shock, the signal is read 1:1, so when impacted, skipping occurs. However, when anti-shock is activated, the sound released from RAM allows the music to continue playing, while the optical head quickly resets and retrieves the signal, thus preventing skipping. This is the general situation. However, this method does not fully meet user requirements, as the time brought by this method is short, usually only 3 seconds, so the chance of skipping is still quite high. Increasing RAM would also raise costs, as RAM is relatively expensive, especially quality RAM.
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