A hardware platform that contains a microcontroller or microprocessor along with supporting components required for prototyping embedded or IoT systems.
Includes:
- Integrated microcontroller or processor
- Built-in power regulation and clock circuitry
- I/O pins for sensors and actuators
- Communication interfaces (USB, UART, I²C, SPI, Wi-Fi, Bluetooth)
- Easy connection to a computer for programming
Advantages
- Reduced development time
- Reduced hardware complexity
- Lower prototyping cost
- Easy testing and debugging
- Large community support
Instead of designing custom electronics for each project, developers can prototype systems quickly using development boards and later move to specialized hardware for production.
Development boards simplify hardware design by providing a ready-to-use platform where developers can write, test, and debug programs without building circuits from scratch. They are widely used for rapid prototyping of IoT systems.
Components
Microcontroller or Microprocessor
The central computing unit that executes the program and controls peripherals.
Memory
Memory stores program code and runtime data.
- Flash memory – program storage
- SRAM – temporary data storage
- EEPROM – non-volatile storage
Input/Output Interfaces
Pins and ports used to connect sensors, actuators, and other electronic components.
Digital Pins
Operate at two discrete voltage levels: HIGH (logic 1) and LOW (logic 0). Voltage levels depend on the board’s logic standard (3.3 V or 5 V).
Can be configured as input or output in software. Used to read binary sensors (buttons, switches) or drive binary actuators (LEDs, relays).
Analog Pins
Read a continuously varying voltage via the on-chip ADC. Output a numeric value proportional to the input voltage. Used to read analog sensors (temperature, light intensity, potentiometers).
GPIO Pins
General Purpose Input/Output. Software-configurable as digital input, digital output, or alternate function (SPI, I²C, UART, PWM). The same physical pin may serve multiple roles depending on firmware configuration.
Most digital pins on a development board are GPIO pins.
PWM Pins
Output a digital square wave with a controllable duty cycle. The duty cycle (fraction of time the signal is HIGH) determines the effective analog output level.
Used to:
- Control motor speed
- Dim LEDs
- Generate audio tones
- Approximate analog output where no DAC is available
Communication Pins
Dedicated pins for serial communication protocols:
- UART
TX (transmit) and RX (receive). Asynchronous serial; used for serial monitor and GPS modules. - SPI
MOSI, MISO, SCK, and CS lines. Synchronous; used for displays, SD cards, ADC chips. - I²C
SDA (data) and SCL (clock). Two-wire bus; supports multiple devices on the same pair of pins.
Power Pins
Supply voltage and ground references:
- VCC / 5 V: regulated 5 V output from the onboard regulator
- 3.3 V: regulated 3.3 V output
- GND: common ground reference
- VIN: unregulated input voltage (bypasses onboard regulator)
Special Function Pins
- RESET
Pulling this pin LOW restarts the microcontroller. - Interrupt pins
Trigger an ISR on a rising, falling, or level change signal. A subset of GPIO pins support external interrupts.
Communication Interfaces
Interfaces that allow the board to communicate with other devices or networks.
Examples:
- UART (Serial communication)
- SPI (Serial Peripheral Interface)
- I²C (Inter-Integrated Circuit)
- Wi-Fi
- Bluetooth
- Ethernet
Power Management
Power circuits regulate voltage and supply power to the board and connected devices.
Development board includes voltage regulators, USB power input and battery support
Programming and Debugging Interface
Interfaces used to upload programs and debug the device.
Examples:
- USB programming interface
- In-Circuit Serial Programming (ICSP)
- Debugging ports
USB-to-Serial Converter Chip
MCUs communicate over UART: a simple two-wire asynchronous serial protocol (TX/RX). Modern computers have no native UART port; they expose USB.
A USB-to-serial converter chip bridges this mismatch. It presents as a USB device to the host and as a UART peripheral to the MCU. The host OS sees it as a virtual COM port (e.g. COM3 on Windows, /dev/ttyUSB0 on Linux).
Why it is needed:
- MCUs do not have native USB hardware (or have it disabled to save power/complexity)
- UART is the standard output channel used by bootloaders and serial monitors
- The converter handles USB enumeration, framing, and voltage-level translation transparently
Common chips:
- CH340 / CH341 (WCH): low-cost; common on budget Arduino clones and NodeMCU boards
- CP2102 / CP2104 (Silicon Labs): higher quality; used on NodeMCU v2 and many ESP boards
- FT232R / FT231X (FTDI): reliable; used on official Arduino Uno and higher-end boards
- PL2303 (Prolific): older; found on early boards
The converter chip is visible to the host only during programming and serial monitoring. It plays no role in the firmware itself once uploaded.