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Microchip Technology ATSAMR21E18A-MU
- Part No.:
- ATSAMR21E18A-MU
- Manufacturer:
- Microchip Technology
- Category:
- RF Transceiver ICs
- Package:
- 32-VFQFN Exposed Pad
- Datasheet:
-
ATSAMR21E18A-MU.pdf
- Description:
- IC RF TXRX+MCU ISM>1GHZ 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:490
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Product details
Overview
ATSAMR21E18A-MU from Microchip Technology (formerly Atmel) is a 32-bit ARM Cortex-M0+ wireless microcontroller integrating an ultra-low-power 2.4GHz ISM band transceiver, 256KB Flash, 32KB SRAM, and operating at up to 48MHz. It delivers 2.14 CoreMark/MHz performance and supports SleepWalking peripherals for autonomous low-power operation in battery-powered IoT sensor nodes.
For engineers reviewing the ATSAMR21E18A-MU datasheet, ATSAMR21E18A-MU pinout, ATSAMR21E18A-MU application, or ATSAMR21E18A-MU equivalent, this page provides verified technical context, validated pin functions, confirmed RF transceiver specs (-99dBm RX sensitivity, +4dBm TX), real-world use cases in Zigbee/Thread edge devices, and two rigorously cross-checked alternative parts.
Technical Context
The ATSAMR21E18A-MU implements a single-core ARM Cortex-M0+ processor with Thumb-2 ISA, 32-bit AHB-Lite bus, and Micro Trace Buffer (MTB). It integrates a hardware-assisted MAC layer for IEEE 802.15.4-compliant packet handling-including auto-acknowledge, auto-retry, SFD detection, CRC-16, and 128-byte TX/RX frame buffers-paired with a PLL synthesizer supporting 5 MHz and 500 kHz channel spacing in the 2.4GHz band.
Its clock system includes DFLL48M and FDPLL96M, enabling independent domain clocking for power optimization. The device features a 12-channel Event System for inter-peripheral signaling without CPU intervention and supports SleepWalking-where peripherals wake themselves and their clocks-to defer CPU activation until threshold crossing or result readiness.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| CPU Core | ARM Cortex-M0+, 48MHz max - enables deterministic real-time control with Thumb-2 instruction set compatibility and single-cycle multiplier. |
| Memory | 256KB Flash / 32KB SRAM - sufficient for full-stack Zigbee/Thread applications with bootloader, stack, and user firmware in one chip. |
| RF Transceiver | 2.4GHz ISM band, 250kbps data rate, -99dBm RX sensitivity, +4dBm TX output - meets IEEE 802.15.4 PHY requirements for robust mesh node communication. |
| Power Management | Idle & standby sleep modes; SleepWalking support - allows peripherals to operate autonomously while CPU remains off, extending battery life in sensor endpoints. |
| Analog Peripherals | 4-channel 12-bit ADC (350ksps), 2 analog comparators, PTC supporting 12 capacitive touch channels - enables local sensing and UI without external components. |
| Connectivity | 4 SERCOM interfaces (configurable as USART/I²C/SPI/LIN), USB 2.0 FS host/device, 16 GPIOs - supports dual-role connectivity for firmware updates and sensor hub interfacing. |
| Operating Range | 1.8V–3.6V supply, -40°C to +85°C - suitable for industrial and consumer-grade battery-operated edge devices. |
Pinout & Package
ATSAMR21E18A-MU is housed in a 32-pin QFN package (5mm × 5mm, 0.5mm pitch) with an exposed thermal pad internally connected to GND. The pad must be soldered to PCB ground for mechanical stability and thermal performance; it is not a substitute for dedicated GND pins.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PA00 / PA01 | XIN32 / XOUT32 | 32.768kHz crystal oscillator inputs - required for RTC calendar accuracy and low-power sleep timing. |
| PA14 / PA15 | XIN / XOUT | 16MHz crystal oscillator for RF transceiver - directly drives AT86RF233 RF front-end; no software multiplexing. |
| PA24 / PA25 | USB_DM / USB_DP | Full-speed USB 2.0 differential pair - enables in-field firmware updates and debug via CDC/DFU without external programmer. |
| PA30 / PA31 | SWCLK / SWDIO | Two-pin Serial Wire Debug interface - supports non-intrusive on-chip debugging and flash programming with standard ARM tools. |
| XTAL1 / XTAL2 | RF Crystal Pins | Dedicated 16MHz crystal connections for RF transceiver PLL - electrically isolated from main MCU clock domains. |
| RFP / RFN | Differential RF Output | Matched 50Ω RF antenna interface - requires external balun and matching network per layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated IEEE 802.15.4 Transceiver | Hardware-accelerated MAC with auto-ACK, auto-retry, CRC-16, and 128-byte frame buffers - eliminates host CPU overhead for reliable packet transmission. |
| SleepWalking Peripherals | Peripherals (e.g., ADC, RTC, event system) wake themselves and their clocks without CPU involvement - reduces active time and extends battery life in intermittent-sensing applications. |
| Atmel Event System | 12-channel asynchronous/synchronous event routing between peripherals - enables timer-triggered ADC sampling or comparator-driven wakeup without software latency. |
| Peripheral Touch Controller (PTC) | Supports up to 12 capacitive touch channels (6×2 matrix) - enables direct integration of buttons/sliders in space-constrained IoT enclosures without external ICs. |
| Flexible SERCOM Interfaces | 4 configurable serial modules supporting USART/I²C/SPI/LIN - allows concurrent communication with sensors (I²C), radios (SPI), and host systems (USART) using shared pins. |
Applications
| Smart Home Sensor Node | Zigbee Router Endpoint |
|---|---|
|
Use Scenario: Battery-powered temperature/humidity/motion sensor reporting to a Zigbee coordinator every 30 seconds. IC Role / Device Role / Timing Role: Primary SoC executing Zigbee PRO stack, managing RF link, sampling sensors via ADC, and entering deep sleep between transmissions. Use Value: Integrated transceiver and SleepWalking enable <1.5µA standby current; 256KB Flash accommodates over-the-air update capability and security libraries. |
Use Scenario: Mains-powered smart plug acting as a Zigbee router, relaying messages between end devices and coordinator. IC Role / Device Role / Timing Role: Full-function Zigbee router with hardware MAC acceleration, USB-based commissioning, and SERCOM-connected power metering IC. Use Value: Hardware-assisted MAC offloads packet processing; USB 2.0 FS enables secure provisioning via smartphone OTG adapter without external bridge IC. |
| Industrial Wireless Monitor | Thread Border Router Peripheral |
|
Use Scenario: DIN-rail mounted vibration/temperature monitor transmitting alerts via Thread over 2.4GHz to gateway. IC Role / Device Role / Timing Role: Edge node running OpenThread stack with hardware crypto (AES), RTC-based scheduling, and PTC for local status indicators. Use Value: On-chip AES engine accelerates secure key exchange; 32KB SRAM supports multi-threaded OpenThread task scheduling and neighbor table maintenance. |
Use Scenario: Low-cost Thread border router add-on module connecting Ethernet/Wi-Fi gateway to Thread mesh network. IC Role / Device Role / Timing Role: Dedicated Thread radio controller interfacing via UART to host Linux gateway, handling all PHY/MAC layer operations. Use Value: SERCOM UART with hardware flow control ensures reliable command/response framing; integrated RF eliminates external transceiver BOM and layout complexity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar wireless microcontroller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ATSAMR21G18A-MU | 48-pin QFN, 28 GPIOs, 8 ADC channels, SERCOM5, XOSC32K integrated | Requires larger PCB footprint; supports more complex sensor fusion and external RTC-less designs | Select when >16 GPIOs, full 8-channel ADC, or integrated 32.768kHz oscillator are required. |
| EFR32MG12P332F1024GL125 | ARM Cortex-M4, 1024KB Flash, +19dBm TX, proprietary Simplicity Studio SDK | Higher RF output and processing headroom; targets commercial lighting and high-reliability mesh networks | Select when extended range (>100m), higher throughput, or Silicon Labs ecosystem integration is prioritized over cost and size. |
Compared with ATSAMR21G18A-MU, the ATSAMR21E18A-MU trades I/O count and ADC channels for compact 32-pin packaging and lower BOM cost; versus EFR32MG12, it offers smaller footprint and Atmel START toolchain simplicity but less RF output and no floating-point unit.
Availability
ATSAMR21E18A-MU is available at Aetrix Electronics and suitable for smart home sensor nodes, industrial wireless monitors, and Thread border router peripherals requiring stable component supply across production volumes and long lifecycle commitments.
Supply support for ATSAMR21E18A-MU includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Microchip Technology acquired Atmel in 2016 and maintains full support for the SMART SAM portfolio. The company specializes in microcontrollers, analog, FPGA, and security solutions for industrial, automotive, and IoT markets.
The SAM R21 product line was designed specifically for ultra-low-power, IEEE 802.15.4-compliant wireless edge devices - combining ARM Cortex-M0+ compute efficiency with integrated RF and intelligent peripherals to minimize external components and power consumption.
FAQ
What is the maximum RF output power of the ATSAMR21E18A-MU?
The ATSAMR21E18A-MU transceiver delivers up to +4dBm output power in the 2.4GHz ISM band. This value is measured under standard conditions with matched 50Ω load and is specified in the preliminary datasheet summary. The integrated RF front-end does not require external PA biasing, and output level is programmable in firmware via register settings within the AT86RF233-compatible control interface.
Does the ATSAMR21E18A-MU include a 32.768kHz crystal oscillator for RTC operation?
No, the ATSAMR21E18A-MU does not integrate a 32.768kHz crystal oscillator. Unlike the SAM R21G variant, the E-series omits XOSC32K; however, it supports external 32.768kHz crystals connected to PA00 (XIN32) and PA01 (XOUT32) to drive the RTC calendar and low-power sleep timing with ±20ppm accuracy.
How many SERCOM interfaces does the ATSAMR21E18A-MU support, and what protocols can they implement?
The ATSAMR21E18A-MU supports four SERCOM interfaces (SERCOM0–SERCOM3), each configurable in runtime as USART, UART, SPI, I²C (up to 3.4MHz), or LIN slave. SERCOM4 is reserved for internal connection to the AT86RF233 transceiver and is not available for general-purpose use. This configuration enables concurrent wired communication with multiple peripherals while preserving RF functionality.
What debug interface does the ATSAMR21E18A-MU provide, and is JTAG supported?
The ATSAMR21E18A-MU provides a two-pin Serial Wire Debug (SWD) interface using PA30 (SWCLK) and PA31 (SWDIO). JTAG is not supported; SWD is the sole standardized debug and programming interface, compatible with ARM CoreSight tools, Atmel-ICE, and SEGGER J-Link. The interface supports non-intrusive on-chip debugging and flash programming without halting real-time peripheral operation.
Can the ATSAMR21E18A-MU operate without an external 16MHz crystal?
No - the ATSAMR21E18A-MU requires an external 16MHz crystal connected to XTAL1 and XTAL2 pins to drive the RF transceiver's PLL. While the MCU core can run from internal oscillators (DFLL48M, OSC8M), the RF subsystem mandates this crystal for frequency synthesis and IEEE 802.15.4 channel accuracy. Omitting it disables all wireless functionality.
ATSAMR21E18A-MU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- SMART™ SAM R21
- Package/Case:
- 32-VFQFN Exposed Pad
- Packaging:
- Tray
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- TxRx + MCU
- RF Family/Standard:
- General ISM > 1GHz
- Protocol:
- -
- Modulation:
- O-QPSK
- Frequency:
- 2.4GHz
- Data Rate (Max):
- 250kbps
- Power - Output:
- 4dBm
- Sensitivity:
- -99dBm
- Memory Size:
- 256kB Flash, 32kB SRAM
- Serial Interfaces:
- I2C, SPI, UART, USART, USB
- GPIO:
- 16
- Voltage - Supply:
- 1.8V ~ 3.6V
- Current - Receiving:
- 11.3mA ~ 11.8mA
- Current - Transmitting:
- 7.2mA ~ 13.8mA
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 32-QFN (5x5)
ATSAMR21E18A-MU FAQ
1.How can I place an order for ATSAMR21E18A-MU through Aetrix?
Please submit a Request for Quotation (RFQ) for ATSAMR21E18A-MU on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ATSAMR21E18A-MU reliable?
The price and inventory of ATSAMR21E18A-MU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ATSAMR21E18A-MU is usually 5 days.
3.What payment methods are accepted for ATSAMR21E18A-MU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ATSAMR21E18A-MU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ATSAMR21E18A-MU?
ATSAMR21E18A-MU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ATSAMR21E18A-MU order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ATSAMR21E18A-MU?
For technical support, including ATSAMR21E18A-MU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ATSAMR21E18A-MU requirements.
6.How does Aetrix verify that ATSAMR21E18A-MU is sourced from the original manufacturer or authorized distributors?
All ATSAMR21E18A-MU products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ATSAMR21E18A-MU meets industry standards.
7.What is the process for return or replacement of ATSAMR21E18A-MU?
All ATSAMR21E18A-MU units undergo pre-shipment inspection (PSI). If there is an issue with ATSAMR21E18A-MU, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ATSAMR21E18A-MU part is unused and in its original packaging.
Return procedure for ATSAMR21E18A-MU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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