1. Description
Atmel® | SMART SAM L21 is a series of Ultra low-power microcontrollers using the 32-bit ARM® Cortex®-
M0+ processor, and ranging from 32- to 64-pins with up to 256KB Flash and 40KB of SRAM. The SAM
L21 devices operate at a maximum frequency of 48MHz and reach 2.46 CoreMark®/MHz. They are
designed for simple and intuitive migration with identical peripheral modules, hex compatible code,
identical linear address map and pin compatible migration paths between all devices in the product
series. 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.
The Atmel SAM L21 devices provide the following features: In-system programmable Flash, 16-channel
direct memory access (DMA) controller, 12-channel Event System, programmable interrupt controller, up
to 51 programmable I/O pins, 32-bit real-time clock and calendar, up to five 16-bit Timer/Counters (TC)
and three Timer/Counters for Control (TCC) where each TC/TCC can be configured to perform frequency
and waveform generation, accurate program execution timing or input capture with time and frequency
measurement of digital signals. The TCs can operate in 8- or 16-bit mode, selected TCs can be cascaded
to form a 32-bit TC, and three timer/counters have extended functions optimized for motor, lighting and
other control applications. Two TCC can operate in 24-bit mode, the third TCC can operate in 16-bit
mode. The series provide one full-speed USB 2.0 embedded host and device interface; up to six Serial
Communication Modules (SERCOM) that each can be configured to act as an USART, UART, SPI, I2C up
to 3.4MHz, SMBus, PMBus, and LIN slave; up to twenty channel 1MSPS 12-bit ADC with programmable
gain and optional oversampling and decimation supporting up to 16-bit resolution, two 12-bit 1MSPS
DACs, two analog comparators with window mode, three independent cascadable OPAMPs supporting
internal connection with others analog features, Peripheral Touch Controller supporting up to 192 buttons,
sliders, wheels and proximity sensing; programmable Watchdog Timer, brown-out detector and power-on
reset and two-pin Serial Wire Debug (SWD) program and debug interface.
All devices have accurate and low-power external and internal oscillators. All oscillators can be used as a
source for the system clock. Different clock domains can be independently configured to run at different
frequencies, enabling power saving by running each peripheral at its optimal clock frequency, and thus
maintaining a high CPU frequency while reducing power consumption.
The SAM L21 devices have four software-selectable sleep modes, idle, standby, backup and off. In idle
mode the CPU is stopped while all other functions can be kept running. In standby all clocks and
functions are stopped except those selected to continue running. In this mode all RAMs and logic
contents are retained. The device supports SleepWalking. This feature allows the peripheral to wake up
from sleep based on predefined conditions, and thus allows some internal operation like DMA transfer
and/or the CPU to wake up only when needed, e.g. when a threshold is crossed or a result is ready. The
Event System supports synchronous and asynchronous events, allowing peripherals to receive, react to
and send events even in standby mode.
The SAM L21 devices have two software-selectable performance levels (PL0 and PL2) allowing the user
to scale the lowest core voltage level that will support the operating frequency. To further minimize
consumption, specifically leakage dissipation, the SAM L21 devices utilizes power domain gating
technique with retention to turn off some logic area while keeping its logic state. This technique is fully
handled by hardware.
The Flash program memory can be reprogrammed in-system through the SWD interface. The same
interface can be used for nonintrusive on-chip debugging of application code. A boot loader running in the
device can use any communication interface to download and upgrade the application program in the
Flash memory.
Atmel SAM L21E / SAM L21G / SAM L21J [DATASHEET]
Atmel-42385J-SAM L21_Datasheet_Complete-06/2016
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