Atmel / Microchip R21 SMART ARM-Based Wireless Microcontrollers

Microchip R21 SMART ARM-Based Wireless Microcontrollers are low power and feature 32-bit ARM® Cortex®-M0+ processors with an integrated 2.4GHz ISM band transceiver. The R21 devices are available in 32- and 48-pin packages with up to 256KB Flash, 32KB of SRAM and operate with a maximum frequency of 48MHz and reach 2.46 Coremark/MHz. The R21 is designed for simple and intuitive migration with identical peripheral modules, hex compatible code, identical linear address map, and pin-compatible migration paths. All devices include intelligent and flexible peripherals, Atmel Event System for inter-peripheral signaling, and support for capacitive touch button, slider, and wheel user interfaces.


  • Processor
    • ARM Cortex-M0+ CPU running at up to 48MHz
    • Single-cycle hardware multiplier
    • Micro Trace Buffer (MTB)
  • Memories
    • 768/256/128/64KB in-system self-programmable Flash
    • 32/16/8KB SRAM
  • System
    • Power-on reset (POR) and brown-out detection (BOD)
    • Internal and external clock options with 48MHz Digital Frequency Locked Loop (DFLL48M) and 48MHz to 96MHz Fractional Digital Phase
    • Locked Loop (FDPLL96M)
    • External Interrupt Controller (EIC)
    • Up to 15 external interrupts
    • One non-maskable interrupt
    • Two-pin Serial Wire Debug (SWD) programming, test, and debugging interface
  • Low Power
    • Idle and standby sleep modes
    • SleepWalking peripherals
  • I/O and Package
    • 16/28 programmable I/O pins
    • 32-pin and 48-pin QFN
  • Operating Voltage
    • 1.8V - 3.6V
  • Peripherals
    • 12-channel Direct Memory Access Controller (DMAC)
    • 12-channel Event System
    • Integrated Ultra Low Power Transceiver for 2.4GHz ISM Band
    • Three 16-bit Timer/Counters (TC), configurable as either:
    • Three 16-bit Timer/Counters for Control (TCC), with extended functions:
    • 32-bit Real Time Counter (RTC) with clock/calendar function
    • Watchdog Timer (WDT)
    • CRC-32 generator
    • One full-speed (12Mbps) Universal Serial Bus (USB) 2.0 interface
    • Up to five Serial Communication Interfaces (SERCOM), each configurable to operate as either:
    • One 12-bit, 350ksps Analog-to-Digital Converter (ADC) with up to eight external channels
    • Two Analog Comparators (AC) with window compare function
    • Peripheral Touch Controller (PTC)


Infographic - Atmel / Microchip R21 SMART ARM-Based Wireless Microcontrollers
Published: 2017-07-25 | Updated: 2022-11-01