Microcontroller peripherals are functional blocks integrated into the chip that enable it to interact with the outside world or carry out specific tasks — often without involving the processor core.

🟠 When selecting a microcontroller, your choice should depend on the required peripherals, not the other way around.

The peripherals of a microcontroller act like its senses, enabling it to interact with the outside world, process analog signals, manage time, communicate with other devices, and perform various application-specific tasks.

Each microcontroller includes a different set of peripheral modules, depends on its architecture, manufacturer, specific model etc, and which determine its capabilities and cost.
Typical peripherals include:

  • ADC (Analog-to-Digital Converter)
  • Timers and PWM Generators
  • Analog Comparators
  • Communication interfaces such as UART (serial port), SPI, I2C, USB, and CAN

Most microcontrollers, regardless of brand or architecture, include a core set of these essential peripherals.

Category How it can be different MCU examples
GPIO Number of pins, alt-functions, open-drain/push-pull, switching speed, pull-up resistors. STM32F103 – basic set, alt-functions via AFIO
ESP32S3 – up to 45 pins, flexible routing via GPIO matrix
RP2040 – 30 GPIO, PIO support
TIMER / PWM Bit depth (8/16/32 bit), number of timers, modes (OneShot, PWM, Capture), channels, dead-time. STM32H7 – advanced timers with dead-time, synchronization
RP2040 – 8 PWM blocks with independent channels
ATmega328P – 3 timers (2×8 bit, 1×16 bit)
UART / USART Number of ports, DMA support, auto-detection of speed, support for IrDA, LIN, RS-485. STM32F4 – up to 6 USARTs, IrDA and SmartCard support
ESP32 – 3 UARTs, all with DMA
RP2040 – 2 UARTs, software implementation via PIO
SPI / I2C Number of modules, speed (up to 80+ MHz), master/slave modes, DMA support, multi-master. STM32L4 – SPI with CRC and NSS support
ESP32S3 – up to 4 SPI/I2C, with DMA and master/slave modes
AVR ATmega328P – I2C (TWI) and SPI with basic functionality
ADC / DAC Bit depth (8-16 bit), number of channels, speed, built-in buffers, calibration. STM32G4 – 16-bit ADC, 2 MSPS
ESP32 – 12-bit ADC (low quality), 2 DAC
RP2040 – 12-bit ADC, no DAC
DMA Number of channels, peripheral support, linked list, circular mode, prio levels. STM32F4 – up to 16 DMA channels, peripherals + memory
RP2040 – 12 channels, programmable transfers
ESP32 – built-in DMA controller with SPI/UART
USB Support for host/device/OTG mode, protocols (CDC, HID, MSC), built-in or external PHY. STM32F103 – USB FS device
STM32H7 – HS + FS, OTG
ESP32S3 – USB OTG (host + device)
Wi-Fi / BLE Version support (BLE 4.2/5.0), co-existence, built-in stack or external module. ESP32S3 – Wi-Fi 2.4 GHz, BLE 5.0
nRF52840 – BLE 5.3, Thread/Zigbee
STM32WB – STM32 + BLE on a single chip
RTC / WDT / Power External quartz support, wakeup from sleep, low power, independence from system clock. STM32L4 – RTC + deep sleep
ESP32 – ULP core, wake-on-touch
AVR – the simplest WDT, deep sleep with interrupts
Specialized PIO, machine vision, crypto modules, LED drivers, graphic accelerators, LCD controllers. RP2040 – 2 PIO blocks
ESP32S3 – AI acceleration + LCD controller
STM32H7 – ChromART GPU, JPEG decoder

💡 Usage examples

DevicePeripherals involved
Smart lampGPIO, PWM, UART (for BLE), ADC (for light sensor)
Weather stationI2C (sensors), ADC (analog sensors), UART (screen), RTC
Robot on wheelsPWM (motors), UART (Bluetooth), SPI (IMU), GPIO
Oscilloscope on MCUADC, DMA, SPI display, USB

🚀 Tips for working with peripherals

  • Use HAL libraries or register access depending on the task.
  • Always initialize peripherals correctly: setting up pins, frequencies, interrupts.
  • Handle errors: buffer overflows, loss of synchronization, etc.
  • Use the datasheet of the microcontroller - everything is described there in detail.