Embedded systems: overview

I. Overview

Embedded Systems: Small computer systems embedded in electronic devices

• The structure is relatively simple, but the basic computer system components are all there
• Low power consumption

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(1) System composition

System Diagram

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1.CPU core: Different processor architectures use different CPUs

• CISC (Complex Instruction Set Architecture)
• RISC (Reduced Instruction Set Architecture)

2. Debug System: Embedded System Debug Interface

• JTAG: Joint Test Action Group
• SWD: Serial Wire Debug

Different device manufacturers have their own emulators (USB to the above protocol)

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3. Storage system: storing instructions and data

• Instruction Storage (Flash/ROM)
• Data Storage (SRAM)

4. Interrupt System: Managing Embedded System Interrupts

• NVIC: Nested Vectored Interrupt Controller, in the ARM core, interrupt management module

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5. Peripheral system: Embedded system peripherals, communicate with the kernel system through the bus

• Address bus
• Control Bus
• Address bus

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(2) Programming

1. Memory Map: Uniform Addressing

Unify addressing of any device (memory, peripherals, etc.) except the CPU, and then access each external device through the address

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2. Manual reading

(1) Overall view the characteristics of the MCU and what peripherals it has

(2) Check the overall hardware block diagram of the MCU to understand the hardware structure of the entire MCU

(3) Check the block diagram of the clock part to find out what clock sources the MCU has and how many frequency clock divisions it can provide

(4) Check the pin diagram of the MCU to know which pins can be used

(5) View peripheral related things according to the corresponding peripheral

• Peripheral functions
• Steps for peripheral configuration
• Peripheral registers

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3. Programming process

(1) Initialization

• Clock on
• Related pin configuration: multiplexing or not
• Peripheral register configuration: function mode selection, clock configuration, working mode configuration
• Enable configuration: peripheral enable, interrupt enable or not

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(2) Data read and write

• Query mode
  • Directly read and write data register buffer
• Interrupt Mode
  • Whether the interrupt flag is generated (interrupt trigger source)
  • Data transmission and reception (data register buffer)
  • Clear the interrupt flag
• DMA Mode

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