Single chip microcomputer STM32L151CCU6

SMD aluminum electrolytic capacitor

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

Photocoupler

A bus in a microcomputer system is a communication pathway that allows multiple components to exchange information. Each component can send or receive data through the bus, making it a crucial part of the system's architecture. The Address Bus (AB) is a one-way communication line used to carry address information from the CPU to memory or peripheral devices. It has a width of 16 bits, which means it can directly access up to 64KB of external memory. The lower 8 bits (A0–A7) are provided by the P0 port via an address latch, while the upper 8 bits (A8–A15) come directly from the P2 port. The Data Bus (DB) is a bidirectional line that transfers data between the CPU, memory, and peripherals. It is 8 bits wide and is typically driven by the P0 port. This bus carries both program instructions and data values during execution. The Control Bus (CB) is a collection of signals that coordinate the activities of the microcontroller. It includes control lines such as RESET, EA, ALE, and PSEN, which are managed through the P3 port. These signals help regulate the timing and flow of operations within the system. Memory in a microcontroller system is divided into two main types: Read-Only Memory (ROM) and Random Access Memory (RAM). ROM stores permanent data such as firmware and system programs, while RAM holds temporary data that is lost when power is removed. ROM can be further categorized into several types: - **Mask ROM**: Pre-programmed by the manufacturer and cannot be altered. - **PROM**: Can be programmed once by the user. - **EPROM**: Erasable and reprogrammable using ultraviolet light. - **EEPROM**: Electrically erasable and programmable, allowing for more flexibility in updates. RAM is volatile and is used for temporary storage of data and intermediate results. It comes in two forms: - **SRAM (Static RAM)**: Retains data as long as power is supplied. - **DRAM (Dynamic RAM)**: Requires periodic refreshing to maintain data integrity. There are also non-volatile memory types like Flash and FRAM. Flash memory is widely used in embedded systems due to its high density, low cost, and ability to retain data without power. FRAM combines the speed of SRAM with the non-volatility of ROM. In a microcontroller, the clock cycle refers to the time taken for a single pulse of the internal clock signal. A machine cycle consists of multiple clock cycles and represents the time required to complete a basic operation. An instruction cycle is made up of one or more machine cycles and defines the time needed to execute a specific command. Assembly language is a low-level programming language that closely mirrors the machine code of the processor. Instructions in assembly correspond directly to the operations the CPU can perform. A byte is a group of 8 bits, while a word is two bytes, and a double word is four bytes. Complements are used to represent negative numbers in binary. The two's complement is the most common method, where a negative number is represented by inverting the bits of the positive number and adding one. Segment addresses and offset addresses are used in systems like the 8086 to manage memory. The physical address is calculated by shifting the segment address left by 4 bits and adding the offset. Code segments store program instructions, data segments hold variables, and stack segments manage function calls and local variables. Interrupts allow the CPU to respond to events such as hardware requests or errors, and interrupt handlers are special routines that process these events. BIOS interrupts provide a standardized way for software to interact with hardware without needing detailed knowledge of the underlying components. They simplify programming by offering pre-written routines for common tasks. Registers, macros, and subroutines are essential tools in assembly programming. Registers act as temporary storage, macros allow repeated code blocks to be reused, and subroutines enable modular programming. Baud rate measures the speed of serial communication, while D/A and A/D conversions translate digital signals to analog and vice versa. Serial and parallel modes describe how data is transmitted across communication channels. Directives guide the assembler during the compilation process, and sleep mode helps reduce power consumption in microcontrollers. Linking connects compiled object files into a final executable. I2C is a serial communication protocol that uses two wires for data and clock signals, while SFRs (Special Function Registers) are memory-mapped registers that control various hardware functions in microcontrollers. Overall, understanding these concepts is essential for working with microcontrollers and designing efficient embedded systems.