Microchip Technology AVR64EA48 User manual

© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 1
AVR64EA48
AVR64EA48 Curiosity Nano Hardware User Guide
Preface
The AVR64EA48 Curiosity Nano evaluation kit (EV66E56A) is a hardware platform to evaluate the AVR® EA Family
microcontrollers. This board has the AVR64EA48 microcontroller (MCU) mounted.
Supported by both MPLAB® X IDE and Microchip Studio, the board provides easy access to the features of the
AVR64EA48 to explore how to integrate the device into a custom design.
The Curiosity Nano series of evaluation boards include an on-board debugger. No external tools are necessary to
program and debug the AVR64EA48.
•MPLAB® X IDE and Microchip Studio - Software to discover, configure, develop, program, and debug
Microchip microcontrollers.
•Code examples on MPLAB Discover - Get started with code examples.
•AVR64EA48 website - Find documentation, data sheets, sample, and purchase microcontrollers.
•AVR64EA48 Curiosity Nano website - Kit information, latest user guide and design documentation.

AVR64EA48
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 2
Table of Contents
Preface........................................................................................................................................................... 1
1. Introduction............................................................................................................................................. 3
1.1. Features....................................................................................................................................... 3
1.2. Board Overview............................................................................................................................3
2. Getting Started........................................................................................................................................ 4
2.1. Curiosity Nano Quick Start MPLAB® Xpress............................................................................... 4
2.2. Quick Start....................................................................................................................................4
2.3. Design Documentation and Relevant Links................................................................................. 5
3. Curiosity Nano.........................................................................................................................................7
3.1. On-Board Debugger Overview..................................................................................................... 7
3.2. Curiosity Nano Standard Pinout................................................................................................. 14
3.3. Power Supply............................................................................................................................. 14
3.4. Low-Power Measurement.......................................................................................................... 18
3.5. Programming External Microcontrollers..................................................................................... 19
3.6. Connecting External Debuggers................................................................................................ 22
4. Hardware Description............................................................................................................................25
4.1. Connectors.................................................................................................................................25
4.2. Peripherals................................................................................................................................. 26
5. Hardware Revision History and Known Issues..................................................................................... 30
5.1. Identifying Product ID and Revision........................................................................................... 30
5.2. Revision 3...................................................................................................................................30
6. Document Revision History...................................................................................................................31
7. Appendix............................................................................................................................................... 32
7.1. Schematic...................................................................................................................................33
7.2. Assembly Drawing......................................................................................................................35
7.3. Curiosity Nano Base for Click boards™...................................................................................... 36
7.4. Disconnecting the On-Board Debugger..................................................................................... 37
7.5. Getting Started with IAR™...........................................................................................................38
Microchip Information................................................................................................................................... 41
The Microchip Website..........................................................................................................................41
Product Change Notification Service.................................................................................................... 41
Customer Support................................................................................................................................. 41
Microchip Devices Code Protection Feature.........................................................................................41
Legal Notice.......................................................................................................................................... 41
Trademarks........................................................................................................................................... 42
Quality Management System................................................................................................................ 43
Worldwide Sales and Service................................................................................................................44

AVR64EA48
Introduction
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 3
1. Introduction
1.1 Features
• AVR64EA48 Microcontroller
• One Yellow User LED
• One Mechanical User Switch
• One 32.768 kHz Crystal
• One 20 MHz Crystal
• On-Board Debugger:
– Board identification in Microchip MPLAB® X IDE and Microchip Studio
– One green power and status LED
– Programming and debugging
– Virtual serial port (CDC)
– Two debug GPIO channels (DGI GPIO)
• USB Powered
• Adjustable Target Voltage:
– MIC5353 LDO regulator controlled by the on-board debugger
– 1.8–5.1V output voltage (limited by USB input voltage)
– 500 mA maximum output current (limited by ambient temperature and output voltage)
1.2 Board Overview
The Microchip AVR64EA48 Curiosity Nano evaluation kit is a hardware platform to evaluate the AVR64EA48
microcontroller.
Figure 1-1. AVR64EA48 Curiosity Nano Board Overview

AVR64EA48
Getting Started
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 4
2. Getting Started
2.1 Curiosity Nano Quick Start MPLAB® Xpress
MPLAB Xpress Cloud-Based IDE is part of the MPLAB Cloud tools ecosystem, leveraging the intuitive MPLAB
Discover for finding projects and code examples and the MPLAB Code Configurator graphical configuration tool to
provide an all-in cloud experience.
Steps to start exploring the Curiosity Nano platform with MPLAB Xpress:
1. Go to www.mplab-xpresside.microchip.com/ to open MPLAB Xpress.
2. Create a new standalone project for AVR64EA48.
3. Use the MPLAB Xpress Code Configurator, or write your code.
4. Compile and download the application HEX file.
5. Connect a USB cable (Standard-A to Micro-B or Micro-AB) between the PC and the debug USB port on the
board.
6. Copy the application HEX file into the CURIOSITY mass storage drive to program the application into the
AVR64EA48.
To use the advanced debug features of the Curiosity Nano kit, package the MPLAB Xpress project for MPLAB
X IDE, and follow the quick start guide in the next section.
2.2 Quick Start
Steps to start exploring the AVR64EA48 Curiosity Nano board:
1. Download Microchip MPLAB® X IDE and MPLAB® XC C Compiler, or download Microchip Studio.
2. Launch MPLAB® X IDE or Microchip Studio.
3. Optional: Use MPLAB® Code Configurator to generate drivers and examples.
4. Write\Develop the application code.
5. Connect a USB cable (Standard-A to Micro-B or Micro-AB) between the PC and the debug USB port on the
board.
6. Program your application onto the device.
The AVR64EA48 device on the AVR64EA48 Curiosity Nano board is programmed and debugged by the
on-board debugger. Therefore, no external programmer or debugger tool is required.
Info:
• MPLAB® X IDE supports XC C compilers and the AVR® and Arm® Toolchains (GCC
Compilers)
• Microchip’s XC8 C Compiler supports all 8-bit PIC® and AVR® microcontrollers
• Included in the Microchip Studio download are the AVR® and Arm® Toolchains (GCC
Compilers)
2.2.1 Driver Installation
When the board connects to the computer for the first time, the operating system will perform a driver software
installation. The driver file supports both 32- and 64-bit versions of Microsoft® Windows®. The drivers for the board
are included with both MPLAB® X IDE and Microchip Studio.

AVR64EA48
Getting Started
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 5
2.2.2 Kit Window
When the board is connected to a computer and powered on, the green status LED will be lit, and both MPLAB®
X IDE and Microchip Studio will auto-detect which boards are connected. The Kit Window in MPLAB® X IDE and
Microchip Studio will present relevant information like data sheets and board documentation.
Tip: If closed, reopen the Kit Window in MPLAB® X IDE through the menu bar Window > Kit Window.
2.2.3 MPLAB® X IDE Device Family Packs
Microchip MPLAB® X IDE requires specific information to support devices and tools. This information is contained
in versioned packs. For the AVR64EA48 Curiosity Nano board, MPLAB® X version 6.0 with device family pack “AVR-
Ex_DFP” version 2.1.48 and tool pack “nEDBG_TP” version 1.10.488 or newer is required. For more information on
packs and how to upgrade them, refer to the MPLAB® X IDE User’s guide - Work with Device Packs.
Tip: The latest device family packs are available through Tools > Packs in MPLAB® X IDE or online at
Microchip MPLAB® X Packs Repository.
2.2.4 Microchip Studio Device Family Pack
Microchip Studio requires specific information to support devices. This information is contained in versioned packs.
For the AVR64EA48 Curiosity Nano board, the device family pack “AVR-Ex_DFP” version 2.2.56 or newer is
required. For more information on packs and how to upgrade them, refer to the Microchip Studio User Guide -
Device Pack Manager.
Tip: The latest device family packs are available through Tools > Device Pack Manager in Microchip
Studio or online at Microchip Studio Packs Repository.
2.3 Design Documentation and Relevant Links
The following list contains links to the most relevant documents and software for the AVR64EA48 Curiosity Nano
board:
•MPLAB® X IDE - MPLAB X IDE is a software program that runs on a PC (Windows®, Mac OS®, Linux®)
to develop applications for Microchip microcontrollers and digital signal controllers. It is named an Integrated
Development Environment (IDE) because it provides a single integrated “environment” to develop code for
embedded microcontrollers.
•Microchip Studio - Free IDE for the development of C/C++ and assembler code for microcontrollers.
•IAR Embedded Workbench® for AVR® - This is a commercial C/C++ compiler available for AVR
microcontrollers. There is a 30-day evaluation version and a 4 KB code-size-limited kick-start version available
from their website.
•MPLAB® XC Compilers - MPLAB® XC8 C Compiler is available as a free, unrestricted-use download.
Microchips MPLAB® XC8 C Compiler is a comprehensive solution for the project’s software development on
Windows®, macOS® or Linux®. MPLAB® XC8 supports all 8-bit PIC® and AVR® microcontrollers (MCUs).
•MPLAB® Xpress Cloud-Based IDE - MPLAB Xpress Cloud-Based IDE is an online development environment
containing the most popular features of our award-winning MPLAB X IDE. This simplified and distilled
application is a faithful reproduction of our desktop-based program, allowing users an easy transition between
the two environments.

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Getting Started
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User Guide DS50003494A-page 6
•MPLAB® Code Configurator - MPLAB Code Configurator (MCC) is a free software plug-in that provides a
graphical interface to configure peripherals and functions specific to your application.
•Microchip Sample Store - Microchip sample store where one can order samples of devices.
•MPLAB Data Visualizer - MPLAB Data Visualizer is a program used for processing and visualizing data. The
Data Visualizer can receive data from various sources, such as serial ports and the on-board debugger’s Data
Gateway Interface, as found on Curiosity Nano and Xplained Pro boards.
•Atmel Data Visualizer - Studio Data Visualizer is a program used for processing and visualizing data. The Data
Visualizer can receive data from various sources such as serial ports, the on-board debugger’s Data Gateway
Interface found on Curiosity Nano and Xplained Pro boards, and power data from the Power Debugger.
•MPLAB Discover - MPLAB Discover is a tool to help you find Microchip example projects and collateral for
Microchip devices.
•AVR64EA48 Curiosity Nano website - Kit information, latest user guide and design documentation.
•AVR64EA48 Curiosity Nano on Microchip Direct - Purchase this kit on Microchip Direct.

AVR64EA48
Curiosity Nano
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 7
3. Curiosity Nano
Curiosity Nano is an evaluation platform of small boards with low pin count microcontroller (MCU) boards with
on-board debuggers and access to most microcontrollers I/Os. The Curiosity Nano platform offers easy integration
with MPLAB® X IDE and Microchip Studio. All boards are identified in the IDE. When connected, a Kit Window
appears with links to key documentation, including relevant user guides, application notes, data sheets, and example
code. Everything is easy to find. The on-board debugger features a virtual serial port (CDC) for serial communication
to a host PC and a Data Gateway Interface (DGI) with debug GPIO pin(s).
3.1 On-Board Debugger Overview
AVR64EA48 Curiosity Nano contains an on-board debugger for programming and debugging. The on-board
debugger is a composite USB device consisting of several interfaces:
• A debugger that can program and debug the AVR64EA48 in both MPLAB® X IDE and Microchip Studio
• A mass storage device that allows drag-and-drop programming of the AVR64EA48
• A virtual serial port (CDC) that is connected to a Universal Asynchronous Receiver/Transmitter (UART) on the
AVR64EA48 and provides an easy way to communicate with the target application through terminal software
• A Data Gateway Interface (DGI) for code instrumentation with logic analyzer channels (debug GPIO) to visualize
program flow
The on-board debugger controls a Power and Status LED (marked PS) on the AVR64EA48 Curiosity Nano board.
The table below shows how the different operation modes control the LED.
Table 3-1. On-Board Debugger LED Control
Operation Mode Power and Status LED
Boot Loader mode The LED blinks slowly during power-up
Power-up The LED is ON
Normal operation The LED is ON
Programming Activity indicator: The LED blinks slowly during programming/debugging
Drag-and-drop
programming Success: The LED blinks slowly for 2 sec.
Failure: The LED blinks rapidly for 2 sec.
Fault The LED blinks rapidly if a power fault is detected
Sleep/Off The LED is OFF. The on-board debugger is either in a sleep mode or powered down.
This can occur if the board is externally powered.
Info: Slow blinking is approximately 1 Hz, and rapid blinking is about 5 Hz.
3.1.1 Debugger
The on-board debugger on the AVR64EA48 Curiosity Nano board appears as a Human Interface Device (HID)
on the host computer’s USB subsystem. The debugger supports full-featured programming and debugging of the
AVR64EA48 by using both MPLAB X IDE and Microchip Studio and some third-party IDEs.

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Remember: Keep the debugger’s firmware up-to-date. Firmware upgrades automatically when using
MPLAB X IDE or Microchip Studio.
3.1.2 Virtual Serial Port (CDC)
The virtual serial port (CDC) is a general purpose serial bridge between a host PC and a target device.
3.1.2.1 Overview
The on-board debugger implements a composite USB device with a standard Communications Device Class (CDC)
interface, which appears on the host as a virtual serial port. Use the CDC to stream arbitrary data between the host
computer and the target in both directions: All characters sent through the virtual serial port on the host computer will
be transmitted as UART on the debugger’s CDC TX pin. The UART characters captured on the debugger’s CDC RX
pin will be returned to the host computer through the virtual serial port.
Figure 3-1. CDC Connection
Target DSC
UART TX
UART RX
Debugger
USB CDC RX
CDC TX
PC
Terminal
Software
Target
Receive
Target
Send
Terminal
Receive
Terminal
Send
Info: The debugger’s CDC TX pin is connected to a UART RX pin on the target for receiving characters
from the host computer, as shown in the figure above. Similarly, the debugger’s CDC RX pin is connected
to a UART TX pin on the target for transmitting characters to the host computer.
3.1.2.2 Operating System Support
On Windows® machines, the CDC will enumerate as Curiosity Virtual COM Port and appear in the Ports section of
the Windows Device Manager. The COM port number can also be found there.
Info: On older Windows systems, the CDC requires a USB driver. Both MPLAB X IDE and Microchip
Studio installationsinclude this driver.
On Linux® machines, the CDC will enumerate and appear as /dev/ttyACM#.
Info: tty* devices belong to the “dialout” group in Linux, so it may be necessary to become a member of
that group to have permission to access the CDC.
On Mac® machines, the CDC will enumerate and appear as /dev/tty.usbmodem#. Depending on the terminal
program used, it will appear in the available list of modems as usbmodem#.

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Info: For all operating systems, use a terminal emulator that supports DTR signaling. See
3.1.2.4. Signaling.
3.1.2.3 Limitations
Not all UART features are implemented in the on-board debugger CDC. The constraints are outlined here:
•Baud rate: Must be in the range of 1200 bps to 500 kbps. Any baud rate outside this range will be set to the
closest limit without warning. Baud rate can be changed on-the-fly.
•Character format: Only 8-bit characters are supported.
•Parity: Can be odd, even, or none.
•Hardware flow control: Not supported.
•Stop bits: One or two bits are supported.
3.1.2.4 Signaling
During USB enumeration, the host OS will start both the communication and data pipes of the CDC interface. At this
point, it is possible to set and read back the baud rate and other UART parameters of the CDC, but data sending and
receiving will not be enabled.
The terminal must assert the DTR signal when it connects to the host. As this is a virtual control signal implemented
on the USB interface, it is not physically present on the board. Asserting the DTR signal from the host will indicate to
the on-board debugger that a CDC session is active. The debugger will enable its level shifters (if available) and start
the CDC data send and receive mechanisms.
Deasserting DTR in debugger firmware version 1.20 or earlier has the following behavior:
• Debugger UART receiver is disabled, and no further data will be transferred to the host computer
• Debugger UART transmitter will continue to send queued data ready for transfer, but no new data is accepted
from the host computer
• Level shifters (if available) are not disabled, and the debugger CDC TX line remains driven
Deasserting DTR in debugger firmware version 1.21 or later has the following behavior:
• Debugger UART receiver is disabled, and no further data will be transferred to the host computer
• Debugger UART transmitter will continue to send queued data ready for transfer, but no new data is accepted
from the host computer
• Once the ongoing transmission is complete, level shifters (if available) are disabled, and the debugger CDC TX
line will become high-impedance
Remember: Set up the terminal emulator to assert the DTR signal. Without the signal, the on-board
debugger will not send or receive data through its UART.
Tip: The on-board debugger’s CDC TX pin will not be driven until the CDC interface is enabled by the
host computer. Also, there are no external pull-up resistors on the CDC lines connecting the debugger
and the target, which means that the lines are floating during power-up. The target device may enable the
internal pull-up resistor on the pin connected to the debugger’s CDC TX pin to avoid glitches resulting in
unpredictable behavior like framing errors.

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Curiosity Nano
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and its subsidiaries
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3.1.2.5 Advanced Use
CDC Override Mode
In ordinary operation, the on-board debugger is a true UART bridge between the host and the device. However, in
certain use cases, the on-board debugger can override the basic Operating mode and use the CDC TX and RX pins
for other purposes.
Dropping a text file into the on-board debugger’s mass storage drive can be used to send characters out of the
debugger’s CDC TX pin. The filename and extension are trivial, but the text file will start with the characters:
CMD:SEND_UART=
Debugger firmware version 1.20 or earlier has the following limitations:
• The maximum message length is 50 characters – all remaining data in the frame are ignored
• The default baud rate used in this mode is 9600 bps, but if the CDC is already active or configured, the
previously used baud rate still applies
Debugger firmware version 1.21 and later has the following limitations/features:
• The maximum message length will vary depending on the MSC/SCSI layer timeouts on the host computer
and/or operating system. A single SCSI frame of 512 bytes (498 characters of payload) is ensured, and files up
to 4 KB will work on most systems. The transfer will complete on the first NULL character encountered in the file.
• The baud rate used is always 9600 bps for the default command:
CMD:SEND_UART=
• Do not use the CDC Override mode simultaneously with data transfer over the CDC/terminal. If a CDC terminal
session is active when receiving a file via the CDC Override mode, it will be suspended for the duration of the
operation and resumed once complete.
• Additional commands are supported with explicit baud rates:
CMD:SEND_9600=
CMD:SEND_115200=
CMD:SEND_460800=
USB-Level Framing Considerations
Sending data from the host to the CDC can be done byte-wise or in blocks, chunked into 64-byte USB frames. Each
frame will be queued for transfer to the debugger’s CDC TX pin. Sending a small amount of data per frame can
be inefficient, particularly at low baud rates, as the on-board debugger buffers frames but not bytes. A maximum of
four 64-byte frames can be active at any time. The on-board debugger will throttle the incoming frames accordingly.
Sending full 64-byte frames containing data is the most efficient method.
When receiving data on the debugger’s CDC RX pin, the on-board debugger will queue up the incoming bytes into
64-byte frames, which are sent to the USB queue for transmission to the host when they are full. Incomplete frames
are also pushed to the USB queue at approximately 100 ms intervals, triggered by USB start-of-frame tokens. Up to
eight 64-byte frames can be active at any time.
An overrun will occur if the host (or the software running on it) fails to receive data fast enough. When this happens,
the last-filled buffer frame recycles instead of being sent to the USB queue, and a complete data frame will be lost. To
prevent this occurrence, the user will ensure that the CDC data pipe is continuously read, or the incoming data rate
will be reduced.
Sending Break Characters
The host can send a UART break character to the device using the CDC, which can be useable for resetting a
receiver state-machine or signalling an exception condition from the host to the application running on the device.
A break character is defined as a sequence of at least 11 zero bits transmitted from the host to the device.
Not all UART receivers have support for detecting a break, but a correctly-formed break character usually triggers a
framing error on the receiver.

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Curiosity Nano
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Sending a break character using the debugger's CDC has the following limitations:
• Sending a break must NOT be done simultaneously as using the CDC Override mode (drag-and-drop). Both
these functions are temporary states, so they must be used independently.
• Sending a break will cause data currently being sent to be lost. Be sure to wait a sufficient amount of time to
allow all characters in the transmission buffer to be sent (see above section) before sending the break, which
is also in line with expected break character usage: For example, reset a receiver state-machine after a timeout
occurs waiting for data to be returned to the host.
• The CDC specification allows for debugger-timed breaks of up to 65534ms in duration to be requested. For
simplicity, the debugger will limit the break duration to maximum 11 bit-durations at its minimum supported baud
rate.
• The CDC specification allows for indefinite host-timed breaks. It is the responsibility of the terminal application/
user to release the break state in this case.
Note: Sending break characters is available in debugger firmware version 1.24 and later.
3.1.3 Mass Storage Device
The on-board debugger includes a simple Mass Storage Device implementation, which is accessible for read/write
operations via the host operating system to which it is connected.
It provides:
• Read access to basic text and HTML files for detailed kit information and support
• Write access for programming Intel® HEX formatted files into the target device’s memory
• Write access for simple text files for utility purposes
3.1.3.1 Mass Storage Device Implementation
The on-board debugger implements a highly optimized variant of the FAT12 file system with several limitations, partly
due to the nature of FAT12 itself and optimizations made to fulfill its purpose for its embedded application.
The Curiosity Nano USB device is USB Chapter 9-compliant as a mass storage device but does not, in any way, fulfill
the expectations of a general purpose mass storage device. This behavior is intentional.
When using the Windows operating system, the on-board debugger enumerates as a Curiosity Nano USB Device
found in the disk drives section of the device manager. The CURIOSITY drive appears in the file manager and claims
the following available drive letter in the system.
The CURIOSITY drive contains approximately one MB of free space and does not reflect the target device’s Flash
size. When programming an Intel HEX file, the binary data are encoded in ASCII with metadata providing a large
overhead, so 1 MB is a trivially chosen value for disk size.
It is not possible to format the CURIOSITY drive. The filename may appear in the disk directory listing when
programming a file to the target, which is merely the operating system’s view of the directory that, in reality, has not
been updated. It is not possible to read out the file contents. Removing and replugging the board will return the file
system to its original state, but the target will still contain the previously programmed application.
Copy a text file starting with “CMD:ERASE” onto the disk to erase the target device.
By default, the CURIOSITY drive contains several read-only files for generating icons as well as reporting status and
linking to further information:
•AUTORUN.ICO – icon file for the Microchip logo
•AUTORUN.INF – system file required for Windows Explorer to show the icon file
•KIT-INFO.HTM – redirect to the development board website
•KIT-INFO.TXT – a text file containing details about the board’s debugger firmware version, board name, USB
serial number, device, and drag-and-drop support
•STATUS.TXT – a text file containing the programming status of the board
Info: The on-board debugger dynamically updates STATUS.TXT. The contents may be cached by the OS
and, therefore, may not reflect the correct status.

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3.1.3.2 Fuse Bytes
Fuse Bytes (AVR® MCU Targets)
When doing drag-and-drop programming, the debugger masks out any fuse bits attempting to disable Unified
Program and Debug Interface (UPDI), meaning that the UPDI pin cannot be used in its Reset or GPIO modes;
selecting one of the alternative functions on the UPDI pin will render the device inaccessible without using an external
debugger capable of high-voltage UPDI activation.
3.1.3.3 Limitations of Drag-and-Drop Programming
Lock Bits
Lock bits included in the hex file will be ignored when using drag-and-drop programming. To program lock bits, use
MPLAB® X IDE or Microchip Studio.
Enabling CRC Check in Fuses
It is not advisable to enable the CRC check fuses in the target device when using drag-and-drop programming
because a subsequent chip erase (which does not affect fuse bits) will cause a CRC mismatch, and the application
will fail to boot. To recover a target from this state, a chip erase must be done using MPLAB® X IDE or Microchip
Studio, which automatically will clear the CRC fuses after erasing.
3.1.3.4 Special Commands
Several utility commands are supported by copying text files to the mass storage disk. The filename or extension is
irrelevant – the command handler reacts to content only.
Table 3-2. Special File Commands
Command Content Description
CMD:ERASE Executes a chip erase of the target
CMD:SEND_UART= Sends a string of characters to the CDC UART. See “CDC
Override Mode.”
CMD:SEND_9600=
CMD:SEND_115200=
CMD:SEND_460800=
Sends a string of characters to the CDC UART at the specified
baud rate. Note that only the baud rates explicitly specified here
are supported. See “CDC Override Mode.” (Debugger firmware
v1.25.6 or newer.)
CMD:RESET Resets the target device by entering Programming mode and
exiting Programming mode immediately afterward. The exact
timing can vary according to the programming interface of the
target device. (Debugger firmware v1.25.6 or newer.)
CMD:POWERTOGGLE Powers down the target and restores it after a 100 ms delay.
If external power is provided, this has no effect. (Debugger
firmware v1.25.6 or newer.)
CMD:0V Powers down the target device by disabling the target supply
regulator. If external power is provided, this has no effect.
(Debugger firmware v1.25.6 or newer.)
CMD:1V8 Sets the target voltage to 1.8V. If external power is provided,
this has no effect. (Debugger firmware v1.25.6 or newer.)
CMD:3V3 Sets the target voltage to 3.3V. If external power is provided,
this has no effect. (Debugger firmware v1.25.6 or newer.)

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Info: The content sent to the mass storage emulated disk triggers the commands listed here and provides
no feedback in the case of either success or failure.
3.1.4 Data Gateway Interface (DGI)
Data Gateway Interface (DGI) is a USB interface transporting raw and timestamped data between on-board
debuggers and host computer-based visualization tools. MPLAB Data Visualizer is used on the host computer to
display any debug GPIO data. It is available as a plug-in for MPLAB X IDE or a stand-alone application that can be
used in parallel with MPLAB X IDE or Microchip Studio.
Although DGI encompasses several physical data interfaces, the AVR64EA48 Curiosity Nano implementation
includes logic analyzer channels:
• Two debug GPIO channels (also known as DGI GPIO)
3.1.4.1 Debug GPIO
Debug GPIO channels are timestamped digital signal lines connecting the target application to a host computer
visualization application. They are typically used to plot low-frequency events on a time axis, such as when given
Application state transitions occur.
The figure below shows the monitoring of the Digital state of a mechanical switch connected to a debug GPIO in
MPLAB Data Visualizer.
Figure 3-2. Monitoring Debug GPIO with MPLAB Data Visualizer
Debug GPIO channels are timestamped, so the resolution of DGI GPIO events is determined by the resolution of the
DGI Timestamp module.
Important: Although signal bursts of higher frequency can be captured, the frequency range of signals for
which debug GPIO can be used is up to about 2 kHz. Attempting to capture signals above this frequency
will result in data saturation and overflow, which may cause the DGI session to be aborted.
3.1.4.2 Timestamping
When captured by the debugger, DGI sources are timestamped. The timestamp counter implemented in the Curiosity
Nano debugger increments at a 2 MHz frequency, providing a timestamp resolution of a half microsecond.

AVR64EA48
Curiosity Nano
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 14
3.2 Curiosity Nano Standard Pinout
The 12-edge connections closest to the USB connector on Curiosity Nano boards have a standardized pinout. The
program/debug pins have different functions depending on the target programming interface, as shown in the table
and figure below.
Table 3-3. Curiosity Nano Standard Pinout
Debugger Signal Target MCU Description
ID — ID line for extensions
CDC TX UART RX USB CDC TX line
CDC RX UART TX USB CDC RX line
DBG0 UPDI Debug data line
DBG1 GPIO1 Debug GPIO1
DBG2 GPIO0 Debug GPIO0
DBG3 RESET Reset line
NC — No connect
VBUS — VBUS voltage for external use
VOFF — Voltage Off input. Disables the target regulator and
target voltage when pulled low.
VTG — Target voltage
GND — Common ground
Figure 3-3. Curiosity Nano Standard Pinout
USB
DEBUGGER
PS LED
NC
ID
CDC RX
CDC TX
DBG1
DBG2
VBUS
VOFF
DBG3
DBG0
GND
VTG
CURIOSITY NANO
3.3 Power Supply
The USB port powers the board. It contains two LDO regulators, one to generate 3.3V for the on-board debugger and
an adjustable LDO regulator for the target AVR64EA48 microcontroller and its peripherals. The voltage from a USB
connector can vary between 4.4V and 5.25V (according to the USB specification) and will limit the maximum voltage
supplied to the target. The figure below shows the entire power supply system on AVR64EA48 Curiosity Nano.

AVR64EA48
Curiosity Nano
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 15
Figure 3-4. Power Supply Block Diagram
USB
Target
MCU
Power source
Cut strap
Power consumer P3V3 DEBUGGER
Power converter
DEBUGGER
Regulator
VUSB
Target
Regulator
Power
Supply
strap
Adjust
Level
shifter
VLVL
VREG
I/O I/O GPIO
straps
I/O
On/Off
Measure On/Off
ID system
#VOFF
PTC
Fuse
Power protection
VBUS
Target
Power
strap
VTG
3.3.1 Target Regulator
The target voltage regulator is a MIC5353 variable output LDO. The on-board debugger can adjust the voltage output
supplied to the board target section by manipulating the MIC5353’s feedback voltage. The hardware implementation
is limited to an approximate voltage range from 1.7V to 5.1V. Additional output voltage limits are configured in
the debugger firmware to ensure that the output voltage never exceeds the hardware limits of the AVR64EA48
microcontroller. The voltage limits configured in the on-board debugger on AVR64EA48 Curiosity Nano are 1.8–5.5V.
Info: The factory default target voltage is 3.3V. It can be changed through MPLAB® X IDE project
properties and in the Microchip Studio device programming dialog. Any change to the target voltage is
persistent, even after a power toggle. The resolution is less than 5 mV but may be limited to 10 mV by the
adjustment program.
Info: The voltage settings setup in MPLAB® X IDE is not applied immediately to the board. The new
voltage setting is applied to the board when accessing the debugger, like pushing the Refresh Debug Tool
Status button in the project dashboard tab or programming/reading program memory.
Info: There is an easy option to adjust the target voltage with a drag-and-drop command text file to the
board, which supports a set of mutual target voltages. See section 3.1.3.4. Special Commands for further
details.
MIC5353 supports a maximum current load of 500 mA. It is an LDO regulator in a small package placed on a small
printed circuit board (PCB), and the thermal shutdown condition can be reached at lower loads than 500 mA. The
maximum current load depends on the input voltage, the selected output voltage, and the ambient temperature.
The figure below shows the safe operating area for the regulator, with an input voltage of 5.1V and an ambient
temperature of 23°C.

AVR64EA48
Curiosity Nano
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 16
Figure 3-5. Target Regulator Safe Operation Area
The voltage output of the target regulator is continuously monitored (measured) by the on-board debugger. An error
condition will be flagged, and the target voltage regulator will be switched off, detecting and handling any short-circuit
conditions if it is more than 100 mV over/under the set device voltage. It will also detect and handle if an external
voltage, which causes VCC_TARGET to move outside the voltage setting monitoring window of ±100 mV, is suddenly
applied to the VTG pin without setting the VOFF pin low.
Info: The on-board debugger has a monitoring window of VCC_TARGET±100 mV, and the status LED will
blink rapidly if the external voltage is under this limit. The on-board debugger status LED will continue to
shine if the external voltage surpasses this limit. When removing the external voltage, the status LED will
start blinking rapidly until the on-board debugger detects the new situation and turns the target voltage
regulator back on.
3.3.2 External Supply
Instead of the on-board target regulator, an external voltage can power the AVR64EA48 Curiosity Nano. When
shorting the Voltage Off (VOFF) pin to the ground (GND) pin, the on-board debugger firmware disables the target
regulator, and it is safe to apply an external voltage to the VTG pin.
It is also safe to apply an external voltage to the VTG pin when no USB cable is plugged into the DEBUG connector
on the board.
The VOFF pin can be tied low/let go at any time, which will be detected by a pin-change interrupt to the on-board
debugger, which controls the target voltage regulator accordingly.
WARNING
Applying an external voltage to the VTG pin without shorting VOFF to GND may cause permanent damage
to the board.
WARNING
Do not apply any voltage to the VOFF pin. Let the pin float to enable the power supply.
WARNING
The absolute maximum external voltage is 5.5V for the on-board level shifters, and the standard operating
condition of the AVR64EA48 is 1.8–5.5V. Applying a higher voltage may cause permanent damage to the
board.

AVR64EA48
Curiosity Nano
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 17
Info: The on-board debugger status LED will blink rapidly and shut the on-board regulator off when
applying an external voltage without pulling the VOFF pin low - and an external supply pulls the voltage
lower than the monitoring window’s lower limit (target voltage setting – 100 mV). The status LED starts
blinking rapidly until the on-board debugger detects the new situation and switches the target voltage
regulator back on if suddenly removing an external voltage when the VOFF pin is not pulled low.
Programming, debugging, and data streaming are still possible with an external power supply. The USB cable will
power the debugger and signal level shifters. Both regulators, the debugger, and the level shifters are powered down
when the USB cable is removed.
Info: In addition to the power consumed by the AVR64EA48 and its peripherals, approximately 100 µA
will be drawn from any external power source to power the on-board level shifters and voltage monitor
circuitry when a USB cable is plugged into the DEBUG connector on the board. When a USB cable is
unplugged, some current is used to supply the level shifter’s voltage pins, which have a worst-case current
consumption of approximately 5 µA. Typical values may be as low as 100 nA.
3.3.3 VBUS Output Pin
AVR64EA48 Curiosity Nano has a VBUS output pin that can be used to power external components that need a 5V
supply. The VBUS output pin has a PTC fuse to protect the USB against short circuits. A side effect of the PTC fuse
is a voltage drop on the VBUS output with higher current loads. The chart below shows the voltage versus the current
load of the VBUS output.
Figure 3-6. VBUS Output Voltage vs. Current
3.3.4 Power Supply Exceptions
This section sums up most exceptions that can occur with the power supply.

AVR64EA48
Curiosity Nano
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 18
Target Voltage Shuts Down
Not reaching the target voltage setting can happen if the target section draws too much current at a given voltage and
cause the thermal shutdown safety feature of the MIC5353 regulator to kick in. To avoid this, reduce the current load
of the target section.
Target Voltage Setting is Not Reached
The USB input voltage (specified to be 4.4V-5.25V) limits the maximum output voltage of the MIC5353 regulator at a
given voltage setting and current consumption. If a higher output voltage is needed, use a USB power source with a
higher input voltage or use an external voltage supply on the VTG pin.
Target Voltage is Different From Setting
An externally applied voltage to the VTG pin without setting the VOFF pin low can cause this. If the target voltage
differs more than 100 mV over/under the voltage setting, the on-board debugger will detect it, and the internal voltage
regulator will shut down. To fix this issue, remove the applied voltage from the VTG pin, and the on-board debugger
will enable the on-board voltage regulator when the new condition is detected. Note that the PS LED will blink rapidly
if the target voltage is below 100 mV of the setting but will ordinarily turn on when higher than 100 mV above it.
No, Or Very Low Target Voltage, and PS LED is Blinking Rapidly
A full or partial short circuit can cause this and is a particular case of the issue above. Remove it, and the on-board
debugger will re-enable the on-board target voltage regulator.
No Target Voltage and PS LED is Lit 1
This situation occurs if the target voltage is set to 0.0V. Set the target voltage to a value within the specified voltage
range for the target device to fix this.
No Target Voltage and PS LED is Lit 2
This situation can be the issue if power jumper J100 and/or J101 are cut, and the target voltage regulator is set to
a value within the specified voltage range for the target device. To fix this, solder a wire/bridge between the pads for
J100/J101, or add a jumper on J101 if a pin-header is mounted.
VBUS Output Voltage is Low or Not Present
If the VBUS output voltage is low or missing, the reason is probably a high-current drain on VBUS, and the protection
fuse (PTC) will reduce the current or cut off completely. Reduce the current consumption on the VBUS pin to fix this
issue.
3.4 Low-Power Measurement
Power to the AVR64EA48 is connected from the on-board power supply and VTG pin through a 100 mil pin-header
marked with “POWER” in silkscreen (J101). To measure the power consumption of the AVR64EA48 and other
peripherals connected to the board, cut the Target Power strap and connect an ammeter over it.
To measure the lowest possible power consumption, follow these steps:
1. Cut the POWER strap with a sharp tool.
2. Solder a 1x2 100 mil pin-header in the footprint.
3. Connect an ammeter to the pin header.
4. Write firmware that:
a. Tri-states any I/O connected to the on-board debugger.
b. Sets the microcontroller in its lowest Power sleep mode.
5. Program the firmware into the AVR64EA48.

AVR64EA48
Curiosity Nano
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 19
Figure 3-7. Target Power Strap
Target Power strap (top side)
Tip: A 100-mil pin-header can be soldered into the Target Power strap (J101) footprint for a simple
connection of an ammeter. Place a jumper cap on the pin-header once the ammeter is no longer needed.
Info: The on-board level shifters will draw a small amount of current even when not used. Maximum 2
µA can be drawn from each I/O pin connected to a level shifter. Therefore, the worst-case maximum for
the five on-board level shifters is 10 μA. Keep any I/O pin connected to a level shifter in the tri-state to
prevent leakage. All I/Os connected to the on-board debugger are listed in 4.2.3.1. On-Board Debugger
Connections. The on-board level shifters can be completely disconnected to prevent leakage, as described
in 7.4. Disconnecting the On-Board Debugger.
3.5 Programming External Microcontrollers
Use the on-board debugger on AVR64EA48 Curiosity Nano to program and debug microcontrollers on external
hardware.
3.5.1 Supported Devices
All external AVR microcontrollers with the UPDI interface can be programmed and debugged with the on-board
debugger with Microchip Studio.
External SAM microcontrollers having a Curiosity Nano Board can be programmed and debugged with the on-board
debugger with Microchip Studio.
AVR64EA48 Curiosity Nano can program and debug external AVR64EA48 microcontrollers with MPLAB X IDE.
3.5.2 Software Configuration
No software configuration is required to program and debug the same device mounted on the board.

AVR64EA48
Curiosity Nano
© 2023 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003494A-page 20
To program and debug a different microcontroller than the one mounted on the board, configure Microchip Studio to
allow an independent selection of devices and programming interfaces.
1. Navigate to Tools > Options through the menu system at the application top.
2. Select the Tools > Tool settings category in the options window.
3. Set the Hide unsupported devices option to False.
Figure 3-8. Hide Unsupported Devices
Info: Microchip Studio allows any microcontroller and interface to be selected when the Hide
unsupported devices setting is set to False - also microcontrollers and interfaces not supported by
the on-board debugger.
3.5.3 Hardware Modifications
The on-board debugger is connected to the AVR64EA48 by default. Remove these connections before any external
microcontroller can be programmed or debugged. Cut the GPIO straps shown in the figure below with a sharp tool to
disconnect the AVR64EA48 from the on-board debugger.