The **MK-R** (commonly referring to the **Arduino MKR** family of boards) is a series of compact, professional-grade development boards designed by Arduino. These boards are specifically engineered for IoT (Internet of Things) applications, balancing a small form factor with powerful processing and connectivity options. --- ## 1. Core Architecture All boards in the MKR family share a standardized hardware architecture to ensure compatibility across different connectivity modules. | Component | Specification | |:---|:---| | **Microcontroller** | SAMD21 Cortex-M0+ 32bit Low Power ARM MCU | | **Operating Voltage** | 3.3V | | **Clock Speed** | 48 MHz | | **Flash Memory** | 256 KB | | **SRAM** | 32 KB | | **Digital I/O Pins** | 8 | | **PWM Pins** | 12 | --- ## 2. Key Electronic Features ### Power Management One of the standout features of the MKR series is the integrated power management system. * **Li-Po Battery Connector:** Most MKR boards feature a dedicated port for 3.7V Lithium-Polymer batteries. * **Charging Circuit:** The board includes an onboard charger that allows the battery to charge automatically when connected to 5V (USB or Vin). * **Low Power Consumption:** The SAMD21 chip is designed to stay in "Deep Sleep" mode, consuming microamps of current, making it ideal for battery-operated remote sensors. ### Connectivity Modules The "R" in the series often highlights the **Radio** or **RF** capabilities. Different MKR boards include specific modules for various protocols: * **MKR WiFi 1010:** Features an ESP32-based module for WiFi and Bluetooth. * **MKR FOX 1200:** Includes a Sigfox module for long-range, low-bandwidth communication. * **MKR WAN 1300/1310:** Equipped with LoRa connectivity for ultra-long-range applications. * **MKR NB 1500:** Uses Narrowband IoT (LTE Cat NB1) for cellular data. ### Security (ECC508 CryptoChip) To ensure secure IoT communication, the boards include a **Microchip ECC508/ECC608 crypto-authentication** chip. This part handles: * Hardware-based key storage. * Encryption for TLS (Transport Layer Security). * Secure connection to cloud services like AWS IoT, Google Cloud, and Azure. --- ## 3. Pinout and Expansion The MKR series follows a specific 28-pin layout, which is smaller than the traditional Arduino Uno. ```text [ USB PORT ] [ Reset Button ] [ LiPo Conn ] 1 [VCC] [Vin] 28 2 [RST] [5V] 27 3 [GND] [GND] 26 4 [A0] [D14] 25 5 [A1] [D13] 24 ... ... ``` ### The MKR Bus Because the pins are standardized, you can use **MKR Shields** (expansion boards) that stack directly on top. Common shields include: * **MKR Relay Shield:** For controlling high-voltage devices. * **MKR SD Proto Shield:** For data logging and prototyping. * **MKR ENV Shield:** With sensors for temperature, humidity, and UV light. --- ## 4. Summary Table | Feature | Benefit | |:---|:---| | **Cortex M0+** | 32-bit processing power in a tiny footprint. | | **3.3V Logic** | Modern standard for interfacing with digital sensors. | | **Battery Port** | Built-in mobile power and charging capability. | | **Crypto Chip** | Industrial-grade security for internet communication. |