SMART ARM-based Microcontrollers
SAM L21 Xplained Pro
USER GUIDE
Preface
The Atmel® SAM L21 Xplained Pro evaluation kit is a hardware platform to
evaluate the ATSAML21J18B microcontroller.
Supported by the Atmel Studio integrated development platform, the kit
provides easy access to the features of the Atmel ATSAML21J18B and
explains how to integrate the device in a custom design.
The Xplained Pro MCU series evaluation kits include an on-board
Embedded Debugger, and no external tools are necessary to program or
debug the ATSAML21J18B.
The Xplained Pro extension kits offers additional peripherals to extend the
features of the board and ease the development of custom designs.
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
Table of Contents
Preface............................................................................................................................ 1
1. Introduction................................................................................................................3
1.1. Features....................................................................................................................................... 3
1.2. Kit Overview................................................................................................................................. 3
2. Getting Started...........................................................................................................5
2.1. Xplained Pro Quick Start.............................................................................................................. 5
2.2. Design Documentation and Relevant Links................................................................................. 5
3. Xplained Pro.............................................................................................................. 7
3.1. Embedded Debugger................................................................................................................... 7
3.2. Xplained Pro Analog Module (XAM).............................................................................................8
3.3. Hardware Identification System....................................................................................................9
3.4. Power Sources........................................................................................................................... 10
3.5. Xplained Pro Headers and Connectors...................................................................................... 11
4. Hardware User Guide..............................................................................................13
4.1. Connectors................................................................................................................................. 13
4.2. Peripherals................................................................................................................................. 17
4.3. Embedded Debugger Implementation........................................................................................19
4.4. SAM L21 Xplained Pro XAM Configuration................................................................................20
5. Appendix..................................................................................................................22
5.1. Getting Started with IAR.............................................................................................................22
5.2. Connecting a SAM-ICE to an Xplained Pro Board..................................................................... 25
6. Hardware Revision History and Known Issues........................................................27
6.1. Identifying Product ID and Revision........................................................................................... 27
6.2. Revision 5...................................................................................................................................27
6.3. Revision 4...................................................................................................................................27
6.4. Revision 3...................................................................................................................................27
7. Document Revision History..................................................................................... 29
8. Evaluation Board/Kit Important Notice.....................................................................30
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
2
1. Introduction
1.1. Features
• ATSAML21J18B microcontroller
• One mechanical reset button
• One mechanical programmable button
• One QTouch® button
• One yellow user LED
• Backup battery
• 32.768kHz crystal
• USB interface, device and reduced host mode
• Three Xplained Pro extension headers
• Embedded Debugger
– Auto-ID for board identification in Atmel Studio
– One yellow status LED
– One green board power LED
– Symbolic debug of complex data types icluding scope information
– Programming and debugging, including power measurements
– Data Gateway Interface: SPI, I2C, four GPIOs
– Virtual COM port (CDC)
• Embedded current measurement circuitry, with Atmel Data Visualizer support for data visualization
• USB powered
• Supported with application examples in Atmel Software Framework
1.2. Kit Overview
The Atmel SAM L21 Xplained Pro evaluation kit is a hardware platform to evaluate the Atmel
ATSAML21J18B.
The kit offers a set of features that enables the ATSAML21J18B user to get started with the SAM L
peripherals right away and to get an understanding of how to integrate the device in their own design.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
3
Figure 1-1. SAM L21 Xplained Pro Evaluation Kit Overview
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
4
2. Getting Started
2.1. Xplained Pro Quick Start
Steps to start exploring the Atmel Xplained Pro platform:
1. Download Atmel Studio.
2. Launch Atmel Studio.
3. Connect the DEBUG USB port on the kit to the PC using a USB cable (Standard-A to Micro-B or
Micro-AB).
When the Xplained Pro MCU kit is connected to the computer for the first time, operating system will
install the software driver. The driver file supports both 32- and 64-bit versions of Microsoft® Windows
XP, Windows Vista®, Windows 7, Windows 8, Windows 10, and Windows Server 2012.
When the Xplained Pro MCU board is powered, the green power LED will glow and Atmel Studio will auto
detect the specific Xplained Pro MCU- and extension board(s) that are connected. Atmel Studio will
present relevant information such as datasheets and kit documentation. The kit landing page in Atmel
Studio also has an option to launch Atmel Software Framework (ASF) example applications for the kit.
The SAM L21 device is programmed and debugged by the on-board Embedded Debugger and therefore
no external programmer or debugger tool is required.
2.2. Design Documentation and Relevant Links
The following list contains links to the most relevant documents and software for the SAM L21 Xplained
Pro.
• Xplained products - Atmel Xplained evaluation kits are a series of easy-to-use evaluation kits for
Atmel microcontrollers and other Atmel products. For low pin-count devices the Xplained Nano
series provides a minimalistic solution with access to all I/O pins of the target microcontroller.
Xplained Mini kits are for medium pin-count devices and adds Arduino Uno compatible header
footprint and a prototyping area. Xplained Pro kits are for medium to high pin-count devices, they
features advanced debugging and standardized extensions for peripheral functions. All these kits
have on board programmers/debuggers which creates a set of low-cost boards for evaluation and
demonstration of features and capabilities of different Atmel products.
• Atmel Studio - Free Atmel IDE for development of C/C++ and assembler code for Atmel
microcontrollers.
• Atmel sample store - Atmel sample store where you can order samples of devices.
• EDBG User Guide - User guide containing more information about the on-board Embedded
Debugger.
• IAR Embedded Workbench® for ARM® - This is a commercial C/C++ compiler that is available for
ARM®. There is a 30 day evaluation version as well as a code size limited kick-start version
available from their website. The code size limit is 16KB for devices with M0, M0+, and M1 cores
and 32KB for devices with other cores.
• Atmel QTouch® Library PTC - QTouch Library for Atmel AVR® and ARM®-based microcontrollers.
• Atmel QTouch® Composer - Tool for developing capacitive buttons, sliders, and wheels
applications.
• Atmel Data Visualizer - Atmel Data Visualizer is a program used for processing and visualizing
data. Data Visualizer can receive data from various sources such as the Embedded Debugger Data
Gateway Interface found on Xplained Pro boards and COM ports.
®
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
5
• Design Documentation - Package containing CAD source, schematics, BOM, assembly drawings,
3D plots, layer plots etc.
• Hardware Users Guide in PDF format - PDF version of this User Guide.
• SAM L21 Xplained Pro on the Atmel website - Atmel website link.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
6
3. Xplained Pro
Xplained Pro is an evaluation platform that provides the full Atmel microcontroller experience. The
platform consists of a series of Microcontroller (MCU) boards and extension boards, which are integrated
with Atmel Studio, have Atmel Software Framework (ASF) drivers and demo code, support data
streaming, and more. Xplained Pro MCU boards support a wide range of Xplained Pro extension boards,
which are connected through a set of standardized headers and connectors. Each extension board has
an identification (ID) chip to uniquely identify which boards are connected to an Xplained Pro MCU board.
This information is used to present relevant user guides, application notes, datasheets, and example
code through Atmel Studio.
3.1. Embedded Debugger
The SAM L21 Xplained Pro contains the Atmel Embedded Debugger (EDBG) for on-board debugging.
The EDBG is a composite USB device of three interfaces; a debugger, Virtual COM Port, and a Data
Gateway Interface (DGI).
Together with Atmel Studio, the EDBG debugger interface can program and debug the ATSAML21J18B.
On SAM L21 Xplained Pro, the SWD interface is connected between the EDBG and the ATSAML21J18B.
The Virtual COM Port is connected to a UART on the ATSAML21J18B and provides an easy way to
communicate with the target application through terminal software. It offers variable baud rate, parity, and
stop bit settings. Note that the settings on the ATSAML21J18B must match the settings given in the
terminal software.
Info: The virtual COM port in the EDBG requires the terminal software to set the data terminal
ready (DTR) signal to enable the UART pins connected to the ATSAML21J18B. If the DTR
signal is not enabled the UART pins on the EDBG is kept in high-z (tristate) rendering the COM
port unusable. The DTR signal is set automatically by some terminal software, but it may have
to be manually enabled in your terminal.
The DGI consists of several physical interfaces for communication with the host computer.
Communication over the interfaces is bidirectional. It can be used to send events and values from the
ATSAML21J18B or as a generic printf-style data channel. Traffic over the interfaces can be timestamped
on the EDBG for more accurate tracing of events. Note that timestamping imposes an overhead that
reduces maximal throughput. Atmel Data Visualizer is used to send and receive data through DGI.
The EDBG controls two LEDs on SAM L21 Xplained Pro; a power LED and a status LED. The table
below shows how the LEDs are controlled in different operation modes.
Table 3-1. EDBG LED Control
Operation mode Power LED Status LED
Normal operation Power LED is lit when power is
applied to the board.
Bootloader mode (idle) The power LED and the status LED blinks simultaneously.
Activity indicator, LED flashes
when any communication
happens to the EDBG.
Bootloader mode (firmware
upgrade)
The power LED and the status LED blinks in an alternating pattern.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
7
For further documentation on the EDBG, see the EDBG User Guide.
3.2. Xplained Pro Analog Module (XAM)
3.2.1. Overview
The Xplained Pro Analog Module (XAM) extends the embedded debugger with high dynamic range
current measurement. This enables power profiling of the target system.
Current output
Range selection
Current input
Calibration ON/OFF
100 mOhm
100 Ohm
Xplained Pro Analog Module (XAM)
The XAM consists of:
• Calibration circuitry
• Voltage reference
• Analog frontend
– Shunt resistors with a range selection switch
– Pre-amplifier
– Two active filters with gain
• Control MCU
– Analog to digital converter
– Signal processing
– Control/communication interface to the EDBG
Calibration
circuitry
Pre-amplifier
20x
20x
voltage
reference
2.7V
2x
16x
Active filter with
gain
GPIO(s)
GPIO
AREF
ADC0
ADC1
GND
GPIO
Control MCU
S&H
ADC
Sync GPIO
I2C
SPI
Clock sync
SWD
EDBG
The current measurement frontend is a high side shunt measurement with a pre-amplifier and a second
active filter stage with gain. The wide dynamic range is achieved by four measurement ranges which are
defined by two shunts and the two parallel second stage active filters with gain.
3.2.2. EDBG Interface
The Xplained Pro Analog Module (XAM) is connected to the EDBG with the following interfaces:
• I2C: This is used to control and configure the XAM
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
8
• SPI: Current measurement data is streamed to the EDBG via this interface. This is a one-way data
transfer channel from the XAM to the EDBG.
• SWD: The MCU in the XAM is programmed via SWD from the EDBG
• GPIO: At least one GPIO that is connected to the EDBG from the target MCU is also connected to
the current measurement unit to enable the user to sync current measurements with his application
• Clock sync: Synchronization signal to synchronize ADC measurements with EDBG
• Reference clock: Reference clock for the XAM
3.2.3. Sample Rate
The raw sampling rate of the Xplained Pro analog module (XAM) is up to 250kHz and with the default
averaging configuration (average of 16 samples) the actual output of the XAM is 16.67kSPS (note that
the XAM output sample rate is not an integer fraction of the raw sampling).
3.2.4. Measurement Ranges and Accuracy
The Xplained Pro analog module has four measurement ranges. These are defined by two shunt resistors
and two gain stages.
Measurement
Hardware Resolution Accuracy Comments
range
Range 1 Low current shunt and
high gain stage
Range 2 Low current shunt and
low gain stage
Range 3 High current shunt and
high gain stage
Range 4 High current shunt and
low gain stage
The ranges are switched automatically by the XAM to achieve best measurement results and the
currently active range is visualized in the Atmel Data Visualizer frontend tool. The maximum voltage drop
over the shunt resistor is 100mV and the XAM will switch the range automatically before this limit is
reached.
3.3. Hardware Identification System
All Xplained Pro compatible extension boards have an Atmel ATSHA204 CryptoAuthentication™ chip
mounted. This chip contains information that identifies the extension with its name and some extra data.
When an Xplained Pro extension is connected to an Xplained Pro MCU board the information is read and
sent to Atmel Studio. The Atmel Kits extension, installed with Atmel Studio, will give relevant information,
code examples, and links to relevant documents. The table below shows the data fields stored in the ID
chip with example content.
20nA 1 LSB ±1% Below 1μA the error will
increase. Typical error for
300nA is 1 LSB ± 10%
150nA 1 LSB ±1%
10μA 1 LSB ±1%
100μA 1 LSB ±1% Above 100mA the error will
increase to 1 LSB ±5% at
400mA. Maximum current is
400mA
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
9
Table 3-2. Xplained Pro ID Chip Content
Data field Data type Example content
Manufacturer ASCII string Atmel'\0'
Product Name ASCII string Segment LCD1 Xplained Pro'\0'
Product Revision ASCII string 02'\0'
Product Serial Number ASCII string 1774020200000010’\0’
Minimum Voltage [mV] uint16_t 3000
Maximum Voltage [mV] uint16_t 3600
Maximum Current [mA] uint16_t 30
3.4. Power Sources
The SAM L21 Xplained Pro kit can be powered by several power sources as listed in the table below.
Table 3-3. Power Sources for SAM L21 Xplained Pro
Power input Voltage requirements Current requirements Connector marking
External power 5V ±2% (±100mV) for
USB host operation.
4.3V to 5.5V if USB host
operation is not
required.
Recommended
minimum is 1A to be
able to provide enough
current for connected
USB devices and the
PWR
board itself.
Recommended
maximum is 2A due to
the input protection
maximum current
specification.
Embedded debugger
USB
Target USB 4.4V to 5.25V (according
4.4V to 5.25V (according
to USB spec.)
to USB spec.)
500mA (according to
USB spec.)
500mA (according to
USB spec.)
DEBUG USB
TARGET USB
The kit will automatically detect which power sources are available and choose which one to use
according to the following priority:
1. External power.
2. Embedded Debugger USB.
3. Target USB.
Info: External power is required when 500mA from a USB connector is not enough to power
the board with possible extension boards. A connected USB device in a USB host application
might easily exceed this limit.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
10
3.5. Xplained Pro Headers and Connectors
3.5.1. Xplained Pro Standard Extension Header
All Xplained Pro kits have one or more dual row, 20-pin, 100mil extension header. Xplained Pro MCU
boards have male headers, while Xplained Pro extensions have their female counterparts. Note that all
pins are not always connected. All connected pins follow the defined pin-out description in the table
below.
The extension headers can be used to connect a variety of Xplained Pro extensions to Xplained Pro MCU
boards or to access the pins of the target MCU on Xplained Pro MCU boards directly.
Table 3-4. Xplained Pro Standard Extension Header
Pin number Name Description
1 ID Communication line to the ID chip on an extension board
2 GND Ground
3 ADC(+) Analog to digital converter, alternatively positive part of differential
ADC
4 ADC(-) Analog to digital converter, alternatively negative part of differential
ADC
5 GPIO1 General purpose I/O
6 GPIO2 General purpose I/O
7 PWM(+) Pulse width modulation, alternatively positive part of differential
PWM
8 PWM(-) Pulse width modulation, alternatively negative part of differential
PWM
9 IRQ/GPIO Interrupt request line and/or general purpose I/O
10 SPI_SS_B/
Slave select for SPI and/or general purpose I/O
GPIO
11 I2C_SDA Data line for I2C interface. Always implemented, bus type.
12 I2C_SCL Clock line for I2C interface. Always implemented, bus type.
13 UART_RX Receiver line of target device UART
14 UART_TX Transmitter line of target device UART
15 SPI_SS_A Slave select for SPI. Should preferably be unique.
16 SPI_MOSI Master out slave in line of serial peripheral interface. Always
implemented, bus type.
17 SPI_MISO Master in slave out line of serial peripheral interface. Always
implemented, bus type.
18 SPI_SCK Clock for serial peripheral interface. Always implemented, bus type.
19 GND Ground
20 VCC Power for extension board
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
11
3.5.2. Xplained Pro Power Header
The power header can be used to connect external power to the SAM L21 Xplained Pro kit. The kit will
automatically detect and switch to any external power if supplied. The power header can also be used as
supply for external peripherals or extension boards. Care must be taken not to exceed the total current
limitation of the on-board regulator when using the 3.3V pin.
Table 3-5. Xplained Pro Power Header
Pin number Pin name Description
1 VEXT_P5V0 External 5V input
2 GND Ground
3 VCC_P5V0 Unregulated 5V (output, derived from one of the input sources)
4 VCC_P3V3 Regulated 3.3V (output, used as main power supply for the kit)
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
12
4. Hardware User Guide
4.1. Connectors
The following sections describes the implementation of the relevant connectors and headers on SAM L21
Xplained Pro and their connection to the ATSAML21J18B. The tables of connections in the sections also
describes which signals are shared between the headers and on-board functionality. Figure 4-1 shows all
available connectors and jumpers on SAM L21 Xplained Pro.
Figure 4-1. SAM L21 Xplained Pro Connector Overview
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
13
4.1.1. Xplained Pro Extension Headers
The SAM L21 Xplained Pro headers EXT1, EXT2, and EXT3 offers access to the I/O of the
microcontroller in order to expand the board e.g., by connecting extensions to the board. These headers
are based on the standard extension header specified in Table 3-4. The headers have a pitch of 2.54mm.
Table 4-1. Extension Header EXT1
EXT1 pin SAM L21
Function Shared functionality
pin
1 [ID] - - Communication line to the ID
chip on an extension board
2 [GND] - - Ground
3 [ADC(+)] PB05 AIN[13]
4 [ADC(-)] PA03 AIN[1]
5 [GPIO1] PB06 GPIO
6 [GPIO2] PB07 GPIO
7 [PWM(+)] PA12 TCC2/WO[0]
8 [PWM(-)] PA13 TCC2/WO[1]
9 [IRQ/GPIO] PB04 IRQ4/GPIO
10 [SPI_SS_B/GPIO] PA02 GPIO SW0
11 [TWI_SDA] PA08 SERCOM2 PAD[0] I²C SDA EXT2, EXT3, and EDBG I²C
12 [TWI_SCL] PA09 SERCOM2 PAD[1] I²C SCL EXT2, EXT3, and EDBG I²C
13 [USART_RX] PB09 SERCOM4 PAD[1] UART RX
14 [USART_TX] PB08 SERCOM4 PAD[0] UART TX
15 [SPI_SS_A] PA05 SERCOM0 PAD[1] SPI SS
16 [SPI_MOSI] PA06 SERCOM0 PAD[2] SPI MOSI
17 [SPI_MISO] PA04 SERCOM0 PAD[0] SPI MISO
18 [SPI_SCK] PA07 SERCOM0 PAD[3] SPI SCK
19 [GND] - - Ground
20 [VCC] - - Power for extension board
Table 4-2. Extension Header EXT2
EXT2 pin SAM L21
Function Shared functionality
pin
1 [ID] - - Communication line to the ID
chip on an extension board
2 [GND] - - Ground
3 [ADC(+)] PA10 AIN[18] / PTC_Y8 Onboard QTouch Button 1
4 [ADC(-)] PA11 AIN[19]
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
14
EXT2 pin SAM L21
Function Shared functionality
pin
5 [GPIO1] PA20 GPIO EDBG GPIO2
6 [GPIO2] PA21 GPIO EDBG GPIO3
7 [PWM(+)] PB12 TC4/WO[0]
8 [PWM(-)] PB13 TC4/WO[1]
9 [IRQ/GPIO] PB14 IRQ14/GPIO
10 [SPI_SS_B/GPIO] PB15 GPIO
11 [TWI_SDA] PA08 SERCOM2 PAD[0] I²C SDA EXT1, EXT3, and EDBG I²C
12 [TWI_SCL] PA09 SERCOM2 PAD[1] I²C SCL EXT1, EXT3, and EDBG I²C
13 [USART_RX] PA19 SERCOM1 PAD[3] UART RX EXT3 UART
14 [USART_TX] PA18 SERCOM1 PAD[2] UART TX EXT3 UART
15 [SPI_SS_A] PA17 GPIO
16 [SPI_MOSI] PB22 SERCOM5 PAD[2] SPI MOSI EXT3 and EDBG SPI
17 [SPI_MISO] PB16 SERCOM5 PAD[0] SPI MISO EXT3 and EDBG SPI
18 [SPI_SCK] PB23 SERCOM5 PAD[3] SPI SCK EXT3 and EDBG SPI
19 [GND] - - Ground
20 [VCC] - - Power for extension board
Table 4-3. Extension Header EXT3
EXT3 pin SAM L21
Function Shared functionality
pin
1 [ID] - - Communication line to the ID
chip on an extension board
2 [GND] - - Ground
3 [ADC(+)] PB00 AIN[8]
4 [ADC(-)] PB01 AIN[9] EDBG GPIO0
5 [GPIO1] PB30 GPIO
6 [GPIO2] PA15 GPIO
7 [PWM(+)] PB10 TCC0/WO[4] LED0
8 [PWM(-)] PB11 TCC0/WO[5]
9 [IRQ/GPIO] PA16 IRQ0/GPIO EDBG GPIO1
10 [SPI_SS_B/GPIO] PA27 GPIO
11 [TWI_SDA] PA08 SERCOM2 PAD[0] I²C SDA EXT1, EXT2, and EDBG I²C
12 [TWI_SCL] PA09 SERCOM2 PAD[1] I²C SCL EXT1, EXT2, and EDBG I²C
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
15
EXT3 pin SAM L21
13 [USART_RX] PA19 SERCOM1 PAD[3] UART RX EXT2 UART
14 [USART_TX] PA18 SERCOM1 PAD[2] UART TX EXT2 UART
15 [SPI_SS_A] PB17 SERCOM5 PAD[1] SPI SS
16 [SPI_MOSI] PB22 SERCOM5 PAD[2] SPI MOSI EXT2 and EDBG SPI
17 [SPI_MISO] PB16 SERCOM5 PAD[0] SPI MISO EXT2 and EDBG SPI
18 [SPI_SCK] PB23 SERCOM5 PAD[3] SPI SCK EXT2 and EDBG SPI
19 [GND] - - Ground
20 [VCC] - - Power for extension board
4.1.2. VDDIO Header
The SAM L21 Xplained Pro has a 2-pin header connecting the power supply from the VCC_MCU net to
VCC_IO net through a jumper. This header can be used to measure the current to the I/O block of the
SAM L21 device by removing the jumper and connect an ammeter. SAM L21 has the possibility to run the
I/O block at a lower voltage level than the MCU is running and thus support interfacing devices that
require lower operating voltages. The header can then be used to power the VCC_IO pin at a different
voltage level by removing the jumper and connecting a power supply with the desired voltage. Refer to
the datasheet of the device for valid operating voltages.
Function Shared functionality
pin
Table 4-4. VDDIO Header
VDDIO header pin Function
1 VCC_MCU power supply
2 VCC_IO power input
4.1.3. USB
The SAM L21 Xplained Pro has a Micro-USB connector for use with the SAM L21 USB module labeled
as TARGET USB on the kit. To be able to detect when a target USB cable is connected in self-powered
mode, a GPIO is used to detect the VBUS voltage on the connector. In USB host mode VBUS voltage is
provided by the kit and can thus not identify a connected device, so another GPIO is used to detect the
USB ID of the device.
Table 4-5. USB Connections
SAM L21 pin USB function Shared functionality
PA14 VBUS Detection Crystal footprint
PB02 USB ID -
PA24 USB D- -
PA25 USB D+ -
4.1.4. Current Measurement Header
An angled 1x2, 100mil pin-header marked with MCU current measurement is located at the upper edge of
the SAM L21 Xplained Pro. All power to the ATSAML21J18B is routed through this header. To measure
the power consumption of the device remove the jumper and replace it with an ammeter.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
16
Caution: Removing the jumper from the pin-header while the kit is powered may cause the
ATSAML21J18B to be powered through its I/O pins. This may cause permanent damage to the
device.
4.1.5. Cortex Debug Connector
SAM L21 Xplained Pro has a 10-pin 50-mil Cortex® Debug Connector that can be used to attach external
debuggers to the ATSAML21J18B.
Table 4-6. Cortex Debug Connector
Cortex Debug
Connector pin
1 VCC_TARGET_P3V3 ATSAML21J18B voltage
2 PA31 SWD data signal EDBG SWD
3 GND Ground
4 PA30 SWD clock signal EDBG SWD
5 GND Ground
6 - -
7 - -
8 - -
9 GND Ground
10 RESETN Target reset signal
4.2. Peripherals
4.2.1. Crystals
The SAM L21 Xplained Pro kit contains one mounted 32.768kHz crystal and a footprint for higher
frequency crystals that can be used as clock sources for the SAM L21. The crystals have cut-straps next
to them that can be used to measure the oscillator safety factor. This is done by cutting the strap and
adding a resistor across the strap. Information about oscillator allowance and safety factor can be found
in application note AVR41001, information about clock calibration and compensation can be found in
application note AT03155.
Pin / Net Function Shared functionality
The footprint for the external crystal is based on the Fox FQ5032B series.
Info: Note that PA14 and PA15 are shared with USB VBUS detect and EXT3 pin 5. To
disconnect PA14 and PA15 from all functionality except XTAL cut J300 and J302.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
17
Table 4-7. External 32.768kHz Crystal
SAM L21 pin Function Shared functionality
PA00 XIN32 -
PA01 XOUT32 -
Table 4-8. External Crystal Footprint
SAM L21 pin Function Shared functionality
PA14 XIN USB VBUS
PA15 XOUT EXT3
4.2.2. Mechanical Buttons
SAM L21 Xplained Pro contains two mechanical buttons. One button is the RESET button connected to
the SAM L21 reset line and the other is a generic user configurable button. When a button is pressed it
will drive the I/O line to GND.
Note: There is no pull-up resistor connected to the generic user button. Remember to enable the
internal pull-up in the SAM L21 to use the button.
Table 4-9. Mechanical Buttons
SAM L21 pin Silkscreen text Shared functionality
RESET RESET -
PA02 SW0 EXT1
4.2.3. LED
There is one yellow LED available on the SAM L21 Xplained Pro board that can be turned on and off. The
LED can be activated by driving the connected I/O line to GND.
Table 4-10. LED Connection
SAM L21 pin Function Shared functionality
PB10 Yellow LED0 EXT3
4.2.4. QTouch Button
There is one self capacitance button available on the SAM L21 Xplained Pro board that can be used as
I/O. This QTouch button is intended to be driven by the built-in Peripheral Touch Controller (PTC) of the
device. A zero ohm resistor is added on the board to easily disconnect the onboard touch buttons from
the extension header, as the I/O lines are shared between the two.
Note: To get started with QTouch refer to Atmel QTouch® Library and Atmel QTouch® Composer.
Table 4-11. QTouch Connection
SAM L21 pin Silkscreen text Shared functionality
PA10 QT BTN1 EXT2
4.2.5. Backup Battery
The SAM L21 Xplained Pro has a backup battery for use with the SAM L21 backup module. The battery
can be connected to the device by placing a jumper over pin 1-2 on the 3-pin VBAT SELECT header.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
18
By default the jumper is placed over pin 2-3 to select the board power supply. This configuration is
selected to avoid draining the battery and can be used during development.
Table 4-12. VBAT SELECT Header
VBAT SELECT pin Function
1 Power from battery
2 PB03/VBAT pin on SAM L21
3 Power from board supply
4.3. Embedded Debugger Implementation
SAM L21 Xplained Pro contains an Embedded Debugger (EDBG) that can be used to program and
debug the ATSAML21J18B using Serial Wire Debug (SWD). The Embedded Debugger also include a
Virtual Com port interface over UART, an Atmel Data Gateway Interface over SPI, and TWI and it
includes four of the SAM L21 GPIOs. Atmel Studio can be used as a front end for the Embedded
Debugger.
4.3.1. Serial Wire Debug
The Serial Wire Debug (SWD) use two pins to communicate with the target. For further information on
how to use the programming and debugging capabilities of the EDBG, see Embedded Debugger.
Table 4-13. SWD Connections
SAM L21 pin Function Shared functionality
PA30 SWD clock Cortex debug connector
PA31 SWD data Cortex debug connector
4.3.2. Virtual COM Port
The Embedded Debugger acts as a Virtual Com Port gateway by using one of the ATSAML21J18B
UARTs. For further information on how to use the Virtual COM port, see Embedded Debugger.
Table 4-14. Virtual COM Port Connections
SAM L21 pin Function Shared functionality
PA22 SERCOM3 PAD[0] UART TXD (SAM
L21 TX line)
PA23 SERCOM3 PAD[1] UART RXD (SAM
L21 RX line)
4.3.3. Atmel Data Gateway Interface
The Embedded Debugger features an Atmel Data Gateway Interface (DGI) by using either a SPI or I²C.
The DGI can be used to send a variety of data from the ATSAML21J18B to the host PC. For further
information on how to use the DGI interface, see Atmel Data Visualizer and the EDBG User Guide.
-
-
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
19
Table 4-15. DGI Interface Connections When Using SPI
SAM L21 pin Function Shared functionality
PB31 GPIO/SPI SS (Slave select) (SAM L21
-
is Master)
PB16 SERCOM5 PAD[0] SPI MISO (Master
EXT2 and EXT3
In, Slave Out)
PB22 SERCOM5 PAD[2] SPI MOSI (Master
EXT2 and EXT3
Out, Slave in)
PB23 SERCOM5 PAD[3] SPI SCK (Clock Out) EXT2 and EXT3
Table 4-16. DGI Interface Connections When Using I²C
SAM L21 pin Function Shared functionality
PA08 SERCOM2 PAD[0] SDA (Data line) EXT1, EXT2, and EXT3
PA09 SERCOM2 PAD[1] SCL (Clock line) EXT1, EXT2, and EXT3
Four GPIO lines are connected to the Embedded Debugger. The EDBG can monitor these lines and time
stamp pin value changes. This makes it possible to accurately time stamp events in the SAM L21
application code. For further information on how to configure and use the GPIO monitoring features, see
Atmel Data Visualizer and the EDBG User Guide.
Table 4-17. GPIO Lines Connected to the EDBG
SAM L21 pin Function Shared functionality
PB01 GPIO0 EXT3
PA16 GPIO1 EXT3
PA20 GPIO2 EXT2
PA21 GPIO3 EXT2
4.4. SAM L21 Xplained Pro XAM Configuration
On the SAM L21 Xplained Pro the MCU and the MCU peripherals (e.g. extensions) are powered by its
own regulator as shown in Figure 4-2. All other parts of the board, mainly embedded debugger and
accompanying Xplained Pro Analog Module (XAM), are powered from a separate regulator. The current
to the MCU and peripherals can be measured by connecting them to the XAM output through jumper
settings.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
20
Figure 4-2. SAM L21 Xplained Pro XAM Implementation Block Diagram
Xplained Pro MCU power
measurement jumper
Target
Peripherals
Current measurement
bypass jumper selection
Xplained Pro Analog
Module (XAM)
Target
Regulator
Target MCU
On the SAM L21 Xplained Pro the XAM can be used in four configurations:
1. No current measurement or external MCU current measurement: The XAM is bypassed and
thus the MCU and peripherals are supplied directly by the regulator. Set both jumpers in the
"BYPASS" position. In this configuration it is also possible to connect external measurement tools
on the Xplained Pro MCU power measurement header to measure MCU current directly instead of
using the XAM.
2. MCU current measurement: The XAM measures only the MCU current while the peripherals are
supplied directly by the regulator. For this configurations place the jumper for "I/O" (peripherals) into
the "BYPASS" position and the "MCU" into the "MEASURE" position.
3. Peripherals measurement: The XAM measures only the peripherals current while the MCU is
directly supplied by the regulator. For this configuration place the jumper for "MCU" into the
"BYPASS" position and the "I/O" jumper into the "MEASURE" position.
4. MCU and peripherals measurement: In this configuration both MCU and peripherals are
measured by the XAM. Place both jumpers on "I/O" and "MCU" headers in the "MEASURE"
position.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
21
5. Appendix
5.1. Getting Started with IAR
IAR Embedded Workbench® for ARM® is a proprietary high efficiency compiler not based on GCC.
Programming and debugging of Xplained Pro kits are supported in IAR™ Embedded Workbench for ARM
using the common CMSIS-DAP interface. Some initial settings have to be set up in the project to get the
programming and debugging to work.
The following steps will explain how to get your project ready for programming and debugging:
1. Make sure you have opened the project you want to configure. Open the OPTIONS dialog for the
project.
2. In the category General Options, select the Target tab. Select the device for the project or, if not
listed, the core of the device.
3. In the category Debugger, select the Setup tab. Select CMSIS DAP as the driver.
4. In the category Debugger, select the Download tab. Check the check box for Use flash loader(s)
option.
5. In the category Debugger > CMSIS DAP, select the Setup tab. Select System (default) as the
reset method.
6. In the category Debugger > CMSIS DAP, select the JTAG/SWD tab. Select SWD as the interface
and optionally select the SWD speed.
Figure 5-1. Select Target Device
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
22
Figure 5-2. Select Debugger
Figure 5-3. Configure Flash Loader
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
23
Figure 5-4. Configure Reset
Figure 5-5. Configure Interface
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
24
5.2. Connecting a SAM-ICE to an Xplained Pro Board
Xplained Pro kits featuring a 10-pin 50mil debug connector can use external debug tools like SAM-ICE
or Atmel-ICE instead of the built-in EDBG. Devices using SWD interface on-board will have a connector
with the pinout compatible with the Cortex Debug Connector.
You can connect the SAM-ICE to the debug connector on an Xplained Pro using either an Atmel-ICE
adapter, SAM-ICE adapter, or a 10-pin 50-mil header to squid cable. When using a squid cable, see the
table and figures below for how to connect the SAM-ICE to the Xplained Pro board.
Table 5-1. Squid Cable Connections
Squid Cable pin SAM-ICE pin
1 (VCC) 1 (VTref)
2 (SWDIO/TMS) 7 (TMS)
3 (GND) 4 (GND)
4 (SWCLK/TCK) 9 (TCK)
5 (GND) 6 (GND)
6 (SWO/TDO) 13 (TDO)
7 (Not used)
8 (Not used)
™
(1)
9 (Not used)
10 (RESET) 15 (RESET)
Note:
1. Optional, if the device has this functionality.
Figure 5-6. SAM-ICE using a Squid Cable
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
25
Figure 5-7. SAM-ICE using an Atmel-ICE Adapter
Important:
If contention with the on-board EDBG occur, power the Xplained Pro board from another input
like the external power header or from the target USB. Physically removing the connection
between the EDBG and the debug header by removing 0Ω resistors, where available, or cutting
the tracks to the EDBG can also be done.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
26
6. Hardware Revision History and Known Issues
6.1. Identifying Product ID and Revision
The revision and product identifier of Xplained Pro boards can be found in two ways; either through Atmel
Studio or by looking at the sticker on the bottom side of the PCB.
By connecting an Xplained Pro MCU board to a computer with Atmel Studio running, an information
window will pop up. The first six digits of the serial number, which is listed under kit details, contain the
product identifier and revision. Information about connected Xplained Pro extension boards will also
appear in the Atmel Kit's window.
The same information can be found on the sticker on the bottom side of the PCB. Most kits will print the
identifier and revision in plain text as A09-nnnn\rr, where nnnn is the identifier and rr is the revision.
Boards with limited space have a sticker with only a QR-code, which contains a serial number string.
The serial number string has the following format:
"nnnnrrssssssssss"
n = product identifier
r = revision
s = serial number
The product identifier for SAM L21 Xplained Pro is A09-2241.
6.2. Revision 5
The device on revision 5 of the kit has been changed from ATSAML21J18B-AUTES to ATSAML21J18BAUT revision C or newer.
6.3. Revision 4
The device on revision 4 of the kit has been changed from ATSAML21J18A-AUTES to ATSAML21J18BAUTES.
The top level order code of the SAM L21 Xplained Pro evaluation kit changed to ATSAML21-XPRO-B for
revision 4 and newer. Revision 3 and earlier
6.4. Revision 3
Revision 3 and previous revisions use ATSAML21J18A-AUTES as the main device, revision 3 is the
initially released revision.
The top level order code of the SAM L21 Xplained Pro evaluation kit is ATSAML21-XPRO for revision 3.
The extra crystal footprint connected to PA14 and PA15 described in Crystals is not present on this
revision.
The overview picture in Figure 1-1 is not applicable for revision 3, see the figure below instead.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
27
Figure 6-1. SAM L21 Xplained Pro Evaluation Kit Overview
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
28
7. Document Revision History
Doc. rev. Date Comment
42405D 08/2016 Updated power supply chapter with target USB as an input source.
42405C 03/2016 Updated for revision 5 of the kit.
42405B 07/2015 Updated for revision 4 of the kit.
42405A 02/2015 Initial document release.
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
29
8. Evaluation Board/Kit Important Notice
This evaluation board/kit is intended for use for FURTHER ENGINEERING, DEVELOPMENT,
DEMONSTRATION, OR EVALUATION PURPOSES ONLY. It is not a finished product and may not
(yet) comply with some or any technical or legal requirements that are applicable to finished products,
including, without limitation, directives regarding electromagnetic compatibility, recycling (WEEE), FCC,
CE or UL (except as may be otherwise noted on the board/kit). Atmel supplied this board/kit "AS IS",
without any warranties, with all faults, at the buyer's and further users' sole risk. The user assumes all
responsibility and liability for proper and safe handling of the goods. Further, the user indemnifies Atmel
from all claims arising from the handling or use of the goods. Due to the open construction of the
product, it is the user's responsibility to take any and all appropriate precautions with regard to
electrostatic discharge and any other technical or legal concerns.
EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER USER NOR ATMEL
SHALL BE LIABLE TO EACH OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES.
No license is granted under any patent right or other intellectual property right of Atmel covering or
relating to any machine, process, or combination in which such Atmel products or services might be or
are used.
Mailing Address:
Atmel Corporation
1600 Technology Drive
San Jose, CA 95110
USA
Atmel SAM L21 Xplained Pro [USER GUIDE]
Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
30
Atmel Corporation 1600 Technology Drive, San Jose, CA 95110 USA T: (+1)(408) 441.0311 F: (+1)(408) 436.4200 | www.atmel.com
©
2016 Atmel Corporation. / Rev.: Atmel-42405D-SAM-L21-Xplained-Pro_User Guide-08/2016
Atmel®, Atmel logo and combinations thereof, Enabling Unlimited Possibilities®, AVR®, QTouch®, and others are registered trademarks or trademarks of Atmel
Corporation in U.S. and other countries. Microsoft®, Windows®, and Windows Vista® are registered trademarks of Microsoft Corporation in U.S. and or other
countries. ARM®, ARM Connected® logo and others are the registered trademarks or trademarks of ARM Ltd. Other terms and product names may be trademarks of
others.
DISCLAIMER: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any
intellectual property right is granted by this document or in connection with the sale of Atmel products. EXCEPT AS SET FORTH IN THE ATMEL TERMS AND
CONDITIONS OF SALES LOCATED ON THE ATMEL WEBSITE, ATMEL ASSUMES NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS, IMPLIED
OR STATUTORY WARRANTY RELATING TO ITS PRODUCTS INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
CONSEQUENTIAL, PUNITIVE, SPECIAL OR INCIDENTAL DAMAGES (INCLUDING, WITHOUT LIMITATION, DAMAGES FOR LOSS AND PROFITS, BUSINESS
INTERRUPTION, OR LOSS OF INFORMATION) ARISING OUT OF THE USE OR INABILITY TO USE THIS DOCUMENT, EVEN IF ATMEL HAS BEEN ADVISED
OF THE POSSIBILITY OF SUCH DAMAGES. Atmel makes no representations or warranties with respect to the accuracy or completeness of the contents of this
document and reserves the right to make changes to specifications and products descriptions at any time without notice. Atmel does not make any commitment to
update the information contained herein. Unless specifically provided otherwise, Atmel products are not suitable for, and shall not be used in, automotive
applications. Atmel products are not intended, authorized, or warranted for use as components in applications intended to support or sustain life.
SAFETY-CRITICAL, MILITARY, AND AUTOMOTIVE APPLICATIONS DISCLAIMER: Atmel products are not designed for and will not be used in connection with any
applications where the failure of such products would reasonably be expected to result in significant personal injury or death (“Safety-Critical Applications”) without
an Atmel officer's specific written consent. Safety-Critical Applications include, without limitation, life support devices and systems, equipment or systems for the
operation of nuclear facilities and weapons systems. Atmel products are not designed nor intended for use in military or aerospace applications or environments
unless specifically designated by Atmel as military-grade. Atmel products are not designed nor intended for use in automotive applications unless specifically
designated by Atmel as automotive-grade.
Loading...