STC32G12K128 Minimum Core Board + Expansion Board

The STC32G12K128 core board and expansion board : Compared to the earlier STC89C51/90C51 series learning boards, the STC32G12K128
core
board boasts significantly more powerful main control chips. For example, performance optimizations and the inclusion of STC32 series chips result in higher performance, making it suitable for handling complex application requirements. Rich peripheral interfaces: The core board typically provides a rich set of peripheral interfaces, such as GPIO (General Purpose Input/Output), UART (Serial Communication Interface), SPI (Serial Peripheral Interface), and I2C (Serial Bus Interface), facilitating connections to various sensors, displays, and other external devices. Low power consumption design: The STC32 series chips are known for their low power consumption, making them suitable for applications with strict power requirements, such as battery-powered devices or devices requiring long-term operation. Extensive development support: The STC series chips have a complete development toolchain and community support, allowing developers to quickly get started and obtain technical support and solutions. Cost-effectiveness: The STC32G12K128 core board typically offers high cost-effectiveness, making it suitable for cost-sensitive projects and applications. These advantages make the STC32G12K128 core board competitive in embedded system development, especially in scenarios requiring high performance, low power consumption, and cost-effectiveness.
The hardware circuit schematic design utilizes
the STC32G12K128 microcontroller
, a high-performance, low-cost 32-bit microcontroller from STC Microelectronics. It boasts powerful performance, featuring a 32-bit ARM Cortex-M3 core with a clock speed of up to 72MHz, providing strong processing and computing capabilities suitable for handling complex algorithms and tasks. It offers rich peripheral interfaces, supporting multiple general-purpose timers, multi-channel ADCs and DACs, and abundant communication interfaces such as UART, SPI, and I2C, meeting the needs of various applications. Its low-power design employs advanced low-power design and technology, demonstrating excellent energy efficiency, making it ideal for applications requiring long-term operation or battery power. The device boasts ample storage space, featuring large-capacity Flash memory and SRAM, facilitating the storage of substantial amounts of program code and data. The
power-off reset circuit
utilizes a unique button. Observing the schematic reveals that when the button is pressed, VCC and +5V are disconnected, powering down the microcontroller. When the button is not pressed, VCC and +5V are connected. This button operates on reverse logic; when the POW button is pressed, the MCU's power supply network VCC rapidly loses power, allowing for efficient USB-HID communication and code downloading.
This method is also known as cold start mode. During a cold start, the internal components of the device operate at a lower temperature than during normal operation. High temperatures accelerate component aging and damage; therefore, cold starts help extend the lifespan of electronic components. Furthermore, cold starts reduce electromagnetic interference. The circuit exhibits higher stability during cold starts, with smoother current and voltage changes, which helps reduce electromagnetic interference generated during startup and improves the device's anti-interference capabilities. To improve system reliability, cold starts allow for more precise current and voltage control of devices during the initial operation phase, reducing the risk of damage caused by voltage transients and current surges during startup, thereby improving the overall system reliability and stability. Therefore, circuit cold starts offer significant advantages in energy efficiency, component lifespan, electromagnetic compatibility, and system reliability, making them a commonly used startup method in many electronic devices and system designs.
The Type-C interface circuit
uses a 16-pin TYPE-C port, supporting the USB 3.0 protocol for easy data transfer and download. The USB-to-
TTL
circuit typically converts the USB interface voltage (usually 5V) to the TTL level (usually 3.3V or 5V) used for serial communication, enabling communication with microcontrollers, single-chip microcomputers, or other electronic devices.
Considering the small size of this core board, the CH340N is used as the USB-to-serial chip in this circuit. The IN5819WS chip in the circuit primarily protects the computer hardware, preventing backflow and damage when the USB is plugged into the computer.
Here are some key features of a USB-to-TTL circuit: Voltage Conversion: Converts the USB 5V voltage to a voltage suitable for TTL logic levels, typically 3.3V or 5V. This conversion is necessary because many microcontrollers and microcontrollers use lower operating voltages (such as 3.3V), while USB usually provides 5V. USB Interface: Typically has a USB Type-A connector for direct insertion into the port of a computer or USB-powered device. TTL Interface: Typically has a pin header connector with pin markings for connecting to the serial communication pins (such as TX, RX, and ground) of the target device (such as a microcontroller). Chip Integration: Typically uses a USB-to-serial (UART) chip, such as CH340 or CP2102, which can handle protocol conversion between USB and serial communication and support virtual COM port drivers. Driver Support: Most USB-to-TTL modules require a specific driver to be installed on the computer so that the operating system recognizes it as a virtual serial port (COM port), allowing communication with the target device via serial communication software. Speed ​​and Stability: USB-to-TTL circuits typically support common serial communication rates, such as 9600 and 115200 baud rates, and offer good stability and reliability, making them suitable for various embedded system development and debugging tasks. They usually draw power from the USB bus, eliminating the need for an external power adapter, which makes them convenient to use and reduces additional power management requirements. Overall, USB-to-TTL circuits are commonly used tools in embedded development, facilitating communication and debugging with a computer and serving as a bridge between a USB host and TTL logic level devices. The M24C02
storage circuit
is a serial I2C bus interface electronic memory chip, typically used as an EEPROM (Electrically Erasable Programmable Read-Only Memory) to store data. Here is a basic introduction to the M24C02: Capacity and Organization: The M24C02 has a 2K-bit (256-byte) storage capacity. The memory is organized into 32 pages, with 8 bytes per page. This organization allows for page-by-page writing, improving write efficiency. Interface: The M24C02 communicates via the I2C bus, a two-wire serial communication protocol including a data line (SDA) and a clock line (SCL).
Features: Electrically Erasable and Programmable: EEPROM allows stored data to be erased and programmed electronically without removing the chip or using ultraviolet light. Low Power Consumption: The M24C02 features low power consumption, effectively reducing power consumption in standby mode. Write Protection: Supports hardware write protection, allowing the memory to be protected from accidental writes by setting specific bits. Lifespan: Offers a high number of erase/write cycles, typically exceeding 10,000 cycles; the actual lifespan depends on usage and conditions. Applications: The M24C02 is commonly used to store infrequently changing data such as device configuration information, system settings, and calibration data. Due to its small capacity, it is suitable for small embedded systems or sensor nodes. Operating Conditions: The M24C02 operates from 1.8V to 5.5V, suitable for the voltage requirements of various electronic devices. In summary, the M24C02 is a common small-capacity EEPROM chip suitable for applications requiring stable and reliable storage. It communicates with the main controller via a simple I2C interface, providing a convenient data storage solution. Regarding
the interactive button circuit
, since serial port code download is used, the STC USB-HID communication protocol is not used. Therefore, the interrupt button on the P32 microcontroller in this computer design functions as a regular button; when the P32 detects a falling edge, it triggers an interrupt and executes the interrupt instruction.
Reference voltage source circuit.
The TL431 is a three-terminal adjustable voltage source that controls its output voltage by adjusting the voltage between its control terminal (Cathode) and anode. It internally contains a comparator and a switch, which together provide a stable reference voltage output.
The key operating principle of the TL431 is as follows:
Comparator: The comparator inside the TL431 compares the voltage between its control terminal (Cathode) and anode (Anode) with an internal reference voltage (typically 2.495V). Feedback Mechanism: When the control terminal voltage is higher than 2.495V, the comparator turns on, lowering the output resistance of the TL431 and thus providing a larger current output. When the control terminal voltage is lower than 2.495V, the comparator turns off, increasing the output resistance and limiting the output current. Stabilized Output: By connecting the control terminal of the TL431 to its output terminal with an external resistor, the voltage at the control terminal can be adjusted, thereby adjusting the output voltage. The TL431 achieves a stable output voltage by adjusting its output current to maintain the control voltage at approximately 2.495V.
(PCB image
, 3D image,
physical sample shown ) I also built an STC32G12K128 expansion board to verify if the core board's functions were implemented.
( Hardware circuit schematic design) The AMS117 LDO step-down circuit is a low-dropout linear regulator (LDO) with a fixed output voltage, providing a high-precision, stable output voltage. The AMS117 is based on a feedback regulation circuit using a reference voltage source and an error amplifier. It uses a differential amplifier to compare the output voltage with the reference voltage, adjusting the output voltage to maintain stability. An LDO typically consists of four main components: a voltage divider sampling circuit, a reference voltage, an error amplifier circuit, and a transistor adjustment circuit. Voltage divider sampling circuit: The output voltage is acquired through resistors R1 and R2; Reference voltage: Generated by a bandgap voltage reference to minimize the impact of temperature changes on the reference; Error amplifier circuit: The acquired voltage is input to the inverting input of the comparator and compared with the reference voltage (the desired output voltage) at the non-inverting input, and the comparison result is amplified; Transistor adjustment circuit: The amplified signal is output to the control electrode of the transistor (the gate of a PMOS transistor or the base of a PNP transistor), so that the amplified signal (current) can control the transistor's on-state voltage, which is a negative feedback adjustment loop. Power switch circuit: When the 2PIN-Type-C is plugged in, the switch is turned on, VBUS and +5V are conducted, and LED7 lights up for indication; when the switch is turned off, LED7 turns off. Buzzer circuit: 8-pin digital tube circuit PCB diagram, 3D diagram, physical diagram, software code design, button selection experiment, buzzer experiment, marquee experiment, interrupt experiment. Bilibili video link: JLCPCB & STC32G12K128 core board