Atmel SAM L21 Xplained Pro User Manual
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.
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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
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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.
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Figure 1-1. SAM L21 Xplained Pro Evaluation Kit Overview
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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.
®
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• 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.
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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.
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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
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• 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
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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.
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