An Overview of Development Board

Introduction

The development board is a printed circuit board used for embedded system development. It includes a series of hardware components such as the central processing unit (CPU), memory, input devices, output devices, data paths/buses, and external resource interfaces.

Development boards are generally customized by embedded system developers according to specific needs, though developers can also research and design a board themselves. These boards are crucial for beginners to learn system hardware and software. A basic Integrated Development Environment (IDE), as well as software source code and hardware schematics, are typically available for these boards. While classic boards included the 51 series, FPGA, and DSP, the modern landscape is dominated by ARM Cortex, RISC-V, and wireless IoT boards (such as the ESP32 series).

A classic ARM9 development board (Historical reference)

In the general embedded system development process, the hardware is divided into two platforms: the development platform (host) and the target platform (target/development board). The host (usually a PC) connects to the target platform through a transmission interface, such as USB (often typically USB-C or Micro-USB in modern boards), UART/Serial, Ethernet, or wireless debugging interfaces like JTAG/SWD over Wi-Fi.

Development port

Once the hardware and specifications are selected, the next step is to establish a development environment. If the embedded operating system (RTOS or Linux) used in the project is not self-developed, most vendors provide an Integrated Development Environment (IDE) and debuggers (Emulators). This accelerates the development process. When using an operating system ported by the manufacturer with sufficient documentation, developers can immediately begin integration for their target platform.

After selecting the operating system, various tools such as compilers and linkers are configured on the host. The compilation parameters vary by environment. The goal is to compile a runnable image file (firmware) according to the hardware specifications and then program it to the target platform. Modern programming is often done via USB using tools like DAPLink, J-Link, or simple drag-and-drop bootloaders (UF2), replacing older, complex parallel port programmers.

Development board classification

Microcontroller

1) 51 series microcontroller

The 51 series remains a classic entry point. While the 8031/8051/8751 were early Intel products, the architecture lives on. ATMEL (now Microchip Technology) produced the popular AT89C51 and AT89S52. Today, modern 8051 variants from companies like Silicon Labs and STC are much faster (1-cycle instruction) than the original designs, though they are largely being replaced by 32-bit ARM Cortex-M0 chips in professional applications.

2) PIC series microcontroller

PIC microcontrollers by Microchip Technology are widely used in industrial control, automotive electronics, and appliances. The PIC family is vast:

• 8-bit: (e.g., PIC16, PIC18) for cost-sensitive, simple tasks.

• 16-bit: (e.g., PIC24, dsPIC) for digital signal control.

• 32-bit: (e.g., PIC32) for high-performance applications.

They are supported by the MPLAB X IDE.

3) AVR series microcontroller

The AVR is an enhanced RISC (Reduced Instruction Set CPU) 8-bit microcontroller architecture. Originally developed by Atmel (acquired by Microchip in 2016), AVR is famous for powering the original Arduino boards (e.g., ATmega328P). They remain popular in education and hobbyist projects due to their simplicity and robustness.

4) ARM development board

ARM-based boards dominate the embedded world. The older ARM7/ARM9/ARM11 classifications have largely been superseded by the Cortex series:

• Cortex-M (M0, M3, M4, M7, M33): Microcontrollers for real-time applications (e.g., STM32, NXP LPC).

• Cortex-A (A7, A53, A72): Application processors capable of running Linux/Android (e.g., Raspberry Pi, BeagleBone).

Major manufacturers include STMicroelectronics, NXP (formerly Freescale), Texas Instruments, and Renesas.

5) RISC-V and IoT Boards (New Addition)

Since 2020, RISC-V (an open-standard instruction set architecture) has surged in popularity. Boards utilizing ESP32-C3 or GD32V chips offer open-source alternatives to ARM. Additionally, wireless-centric SoCs like the Espressif ESP32 series (providing Wi-Fi and Bluetooth) have become the standard for IoT development due to their high performance and low cost.

CPLD/FPGA

CPLD (Complex Programmable Logic Device) and FPGA (Field-Programmable Gate Array) are digital integrated circuits that allow users to program logic functions via hardware description languages (Verilog/VHDL). Major players include AMD (formerly Xilinx) and Intel (formerly Altera). These boards are essential for parallel processing, AI acceleration, and custom logic design.

DSP

DSP (Digital Signal Processor) chips are specialized for high-speed mathematical processing (e.g., audio, video, radar). While standalone DSPs (like TI's C6000 series) exist, many modern microcontrollers (like the ARM Cortex-M4 and M7) now include "DSP instructions," allowing general-purpose chips to handle signal processing tasks, reducing the need for separate DSP boards in mid-range applications.

ARM (Architecture Note)

ARM (Advanced RISC Machines) designs the core architecture but licenses it to other manufacturers. It features low power consumption and high performance, making it the standard for mobile devices and embedded systems. The architecture has evolved from 32-bit (ARMv7) to 64-bit (ARMv8/v9), powering everything from smartwatches to supercomputers.

MIPS

MIPS was historically a significant RISC architecture used in routers and gaming consoles. However, in recent years, the industry has largely shifted toward ARM and RISC-V. While MIPS boards still exist in legacy networking equipment, new development is less common compared to other architectures.

PPC

PowerPC (Performance Optimization With Enhanced RISC – Performance Computing) is a RISC architecture created by the Apple-IBM-Motorola alliance. While it was once found in Apple computers and game consoles (like the Wii and Xbox 360), it is now primarily used in niche high-reliability sectors such as automotive engine control and aerospace (e.g., by NXP and ST). It is less common in general-purpose development boards today.

Components of a development board

Embedded microprocessor

The embedded microprocessor is the heart of the board. Unlike general-purpose PC CPUs (x86), these are optimized for low power and specific tasks. Today, the market has consolidated heavily around ARM and RISC-V architectures. A modern trend is the SoC (System on Chip), where the CPU, GPU, NPU (Neural Processing Unit), and wireless modems are integrated into a single silicon die.

Memory

Embedded systems rely on a hierarchy of memory:

• Cache: Integrated directly into the CPU core for ultra-fast access.

• Main Memory (RAM): Stores running programs and data. In MCUs, this is usually SRAM (tens of kilobytes). In Linux boards (SBCs), this is LPDDR RAM (1GB to 8GB).

• Storage (Flash): Replaces the hard drive.

• NOR Flash: Used in microcontrollers for code execution (XIP).

• NAND Flash / eMMC: Used in Linux boards for large data storage.

• NOR Flash remains critical for bootloaders and BIOS due to its reliability.

Universal interface

Interfaces allow the system to interact with the world. Modern development boards feature updated connectivity standards:

• Communication: USB (Type-C/OTG), Ethernet (Gigabit), CAN Bus (Automotive).

• Wireless: Wi-Fi 6, Bluetooth 5.0/LE, LoRa, Zigbee.

• Sensors/Control: I2C, SPI, UART, GPIO, PWM, ADC/DAC.

• Multimedia: HDMI, MIPI DSI (Display), MIPI CSI (Camera), and I2S (Audio).

These rich interfaces allow developers to prototype complex systems, from smart home devices to industrial automation robots, on a single board.