PIC18F16Q41 Curiosity Nano
PIC18F16Q41 Curiosity Nano Hardware User Guide
Preface
The PIC18F16Q41 Curiosity Nano Evaluation Kit is a hardware platform to evaluate microcontrollers in the
PIC18‑Q41 Family. This board has the PIC18F16Q41 microcontroller (MCU) mounted.
Supported by MPLAB® X IDE, the board provides easy access to the features of the PIC18F16Q41 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 PIC18F16Q41.
• MPLAB® X IDE - Software to discover, configure, develop, program, and debug Microchip microcontrollers.
• Code examples on GitHub - Get started with code examples.
• PIC18F16Q41 website - Find documentation, data sheets, sample, and purchase microcontrollers.
• PIC18F16Q41 Curiosity Nano website - Kit information, latest user guide, and design documentation.
© 2020 Microchip Technology Inc.
User Guide
DS50003048A-page 1
PIC18F16Q41 Curiosity Nano
Table of Contents
Preface........................................................................................................................................................... 1
1. Introduction............................................................................................................................................. 4
1.1. Features....................................................................................................................................... 4
1.2. Board Overview............................................................................................................................4
2. Getting Started........................................................................................................................................ 5
2.1. Quick Start....................................................................................................................................5
2.1.1. Driver Installation...........................................................................................................5
2.1.2. Kit Window.....................................................................................................................5
2.1.3. MPLAB® X IDE Device Family Packs............................................................................5
2.2. Design Documentation and Relevant Links................................................................................. 5
3. Preprogrammed Application....................................................................................................................7
4. Curiosity Nano.........................................................................................................................................8
4.1. On-Board Debugger Overview..................................................................................................... 8
4.1.1. Debugger.......................................................................................................................8
4.1.2. Virtual Serial Port (CDC)................................................................................................9
4.1.2.1. Overview..................................................................................................... 9
4.1.2.2. Operating System Support.......................................................................... 9
4.1.2.3. Limitations................................................................................................. 10
4.1.2.4. Signaling....................................................................................................10
4.1.2.5. Advanced Use........................................................................................... 11
4.1.3. Mass Storage Device...................................................................................................11
4.1.3.1. Mass Storage Device Implementation.......................................................12
4.1.3.2. Configuration Words..................................................................................12
4.1.3.3. Special Commands................................................................................... 12
4.1.4. Data Gateway Interface (DGI)..................................................................................... 13
4.1.4.1. Debug GPIO..............................................................................................13
4.1.4.2. Timestamping............................................................................................14
4.2. Curiosity Nano Standard Pinout................................................................................................. 14
4.3. Power Supply............................................................................................................................. 15
4.3.1. Target Regulator.......................................................................................................... 15
4.3.2. External Supply............................................................................................................17
4.3.3. VBUS Output Pin.........................................................................................................17
4.3.4. Power Supply Exceptions............................................................................................18
4.4. Low-Power Measurement.......................................................................................................... 19
4.5. Programming External Microcontrollers..................................................................................... 20
4.5.1. Supported Devices...................................................................................................... 20
4.5.2. Software Configuration................................................................................................ 20
4.5.3. Hardware Modifications............................................................................................... 21
4.5.4. Connecting to External Microcontrollers...................................................................... 22
4.6. Connecting External Debuggers................................................................................................ 23
5. Hardware User Guide........................................................................................................................... 25
5.1. Connectors.................................................................................................................................25
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User Guide
DS50003048A-page 2
PIC18F16Q41 Curiosity Nano
5.1.1. PIC18F16Q41 Curiosity Nano Pinout..........................................................................25
5.1.2. Using Pin Headers.......................................................................................................25
5.1.3. Operational Amplifier................................................................................................... 26
5.2. Peripherals................................................................................................................................. 26
5.2.1. LED..............................................................................................................................27
5.2.2. Mechanical Switch.......................................................................................................27
5.2.3. Crystal..........................................................................................................................27
5.2.4. On-Board Debugger Implementation...........................................................................28
5.2.4.1. On-Board Debugger Connections............................................................. 28
6. Hardware Revision History and Known Issues..................................................................................... 29
6.1. Identifying Product ID and Revision........................................................................................... 29
6.2. Revision 3...................................................................................................................................29
6.3. Revision 2...................................................................................................................................29
7. Document Revision History...................................................................................................................30
8. Appendix............................................................................................................................................... 31
8.1. Schematic...................................................................................................................................31
8.2. Assembly Drawing......................................................................................................................33
8.3. Curiosity Nano Base for Click boards™...................................................................................... 34
8.4. Disconnecting the On-Board Debugger..................................................................................... 35
The Microchip Website.................................................................................................................................37
Product Change Notification Service............................................................................................................37
Customer Support........................................................................................................................................ 37
Microchip Devices Code Protection Feature................................................................................................ 37
Legal Notice................................................................................................................................................. 38
Trademarks.................................................................................................................................................. 38
Quality Management System....................................................................................................................... 39
Worldwide Sales and Service.......................................................................................................................40
© 2020 Microchip Technology Inc.
User Guide
DS50003048A-page 3
1. Introduction
User Switch
(SW0)
User LED
(LED0)
PIC18F16Q41
MCU
32.768 kHz
Crystal Footprint
Debugger
Power/Status
LED
Micro-USB
Connector
1.1 Features
• PIC18F16Q41 Microcontroller
• One Yellow User LED
• One Mechanical User Switch
• Footprint for 32.768 kHz Crystal
• On-Board Debugger:
– Board identification in Microchip MPLAB® X IDE
– One green power and status LED
– Programming and debugging
– Virtual serial port (CDC)
– One debug GPIO channel (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)
PIC18F16Q41 Curiosity Nano
Introduction
1.2 Board Overview
The Microchip PIC18F16Q41 Curiosity Nano Evaluation Kit is a hardware platform to evaluate the PIC18F16Q41
microcontroller.
Figure 1-1. PIC18F16Q41 Curiosity Nano Board Overview
© 2020 Microchip Technology Inc.
User Guide
DS50003048A-page 4
2. Getting Started
2.1 Quick Start
Steps to start exploring the PIC18F16Q41 Curiosity Nano board:
1. Download Microchip MPLAB® X IDE.
2. Download MPLAB® XC C Compiler.
3. Launch MPLAB® X IDE.
4. Optional: Use MPLAB® Code Configurator to generate drivers and examples.
5. Write your application code.
6. Connect a USB cable (Standard-A to Micro-B or Micro-AB) between the PC and the debug USB port on the
board.
2.1.1 Driver Installation
When the board is connected to your 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® XP, Windows Vista®,
Windows 7, Windows 8, and Windows 10. The drivers for the board are included with MPLAB® X IDE.
PIC18F16Q41 Curiosity Nano
Getting Started
2.1.2 Kit Window
Once the board is powered, the green status LED will be lit, MPLAB® X IDE will auto-detect which boards are
connected. The Kit Window in MPLAB® X IDE will present relevant information like data sheets and board
documentation. The PIC18F16Q41 device on the PIC18F16Q41 Curiosity Nano board is programmed and debugged
by the on-board debugger and, therefore, no external programmer or debugger tool is required.
Tip: The Kit Window can be opened in MPLAB® X IDE through the menu bar Window > Kit Window.
2.1.3 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 PIC18F16Q41 Curiosity Nano, board MPLAB® X version 5.40 with device family pack
“PIC18F-Q_DP” version 1.8 and tool pack “nEDBG_TP” version 1.4 or newer are 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 Design Documentation and Relevant Links
The following list contains links to the most relevant documents and software for the PIC18F16Q41 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 called an Integrated
Development Environment (IDE) because it provides a single integrated “environment” to develop code for
embedded microcontrollers.
© 2020 Microchip Technology Inc.
User Guide
DS50003048A-page 5
PIC18F16Q41 Curiosity Nano
Getting Started
• 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 your project’s software development on
Windows®, macOS® or Linux®. MPLAB® XC8 supports all 8-bit PIC® and AVR® microcontrollers (MCUs).
• 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 you 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 on-board debugger’s Data
Gateway Interface, as found on Curiosity Nano and Xplained Pro boards.
• Microchip PIC® and AVR® Examples - Microchip PIC and AVR Device Examples is a collection of examples
and labs that use Microchip development boards to showcase the use of PIC and AVR device peripherals.
• Microchip PIC® and AVR® Solutions - Microchip PIC and AVR Device Solutions contains complete
applications for use with Microchip development boards, ready to be adapted and extended.
• PIC18F16Q41 Curiosity Nano website - Kit information, latest user guide, and design documentation.
• PIC18F16Q41 Curiosity Nano on Microchip Direct - Purchase this kit on Microchip Direct.
© 2020 Microchip Technology Inc.
User Guide
DS50003048A-page 6
3. Preprogrammed Application
The PIC18F16Q41 mounted on the Curiosity Nano Evaluation Kit is preprogrammed with an application ready to
utilize the integrated operational amplifier.
To get started with the application, find the user guide, code, and hex files for this application available online on
GitHub.
PIC18F16Q41 Curiosity Nano
Preprogrammed Application
© 2020 Microchip Technology Inc.
User Guide
DS50003048A-page 7
4. Curiosity Nano
Curiosity Nano is an evaluation platform of small boards with access to most of the microcontrollers I/Os. The
platform consists of a series of low pin count microcontroller (MCU) boards with on-board debuggers, which are
integrated with MPLAB® X IDE. Each board is identified in the IDE. When plugged in, a Kit Window is displayed 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).
4.1 On-Board Debugger Overview
PIC18F16Q41 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 PIC18F16Q41 in MPLAB® X IDE
• A mass storage device that allows drag-and-drop programming of the PIC18F16Q41
• A virtual serial port (CDC) that is connected to a Universal Asynchronous Receiver/Transmitter (UART) on the
PIC18F16Q41, 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 PIC18F16Q41 Curiosity Nano board.
The table below shows how the LED is controlled in different operation modes.
Table 4-1. On-Board Debugger LED Control
PIC18F16Q41 Curiosity Nano
Curiosity Nano
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
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.
4.1.1 Debugger
The on-board debugger on the PIC18F16Q41 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
PIC18F16Q41 using MPLAB® X IDE.
Success: The LED blinks slowly for 2 sec
Failure: The LED blinks rapidly for 2 sec
This can occur if the board is externally powered.
Info: Slow blinking is approximately 1 Hz, and rapid blinking is approximately 5 Hz.
© 2020 Microchip Technology Inc.
User Guide
DS50003048A-page 8
Remember: Keep the debugger’s firmware up-to-date. Firmware upgrades are automatically done when
Target MCU
UART TX
UART RX
Debugger
USB
CDC RX
CDC TX
PC
Terminal
Software
Target
Receive
Target
Send
Terminal
Receive
Terminal
Send
using MPLAB® X IDE.
4.1.2 Virtual Serial Port (CDC)
The virtual serial port (CDC) is a general purpose serial bridge between a host PC and a target device.
4.1.2.1 Overview
The on-board debugger implements a composite USB device that includes a standard Communications Device Class
(CDC) interface, which appears on the host as a virtual serial port. The CDC can be used to stream arbitrary data in
both directions between the host computer and the target: All characters sent through the virtual serial port on the
host computer will be transmitted as UART on the debugger’s CDC TX pin, and UART characters captured on the
debugger’s CDC RX pin will be returned to the host computer through the virtual serial port.
Figure 4-1. CDC Connection
PIC18F16Q41 Curiosity Nano
Curiosity Nano
Info: As shown in Figure 4-1, the debugger’s CDC TX pin is connected to a UART RX pin on the target
for receiving characters from the host computer. Similarly, the debugger’s CDC RX pin is connected to a
UART TX pin on the target for transmitting characters to the host computer.
4.1.2.2 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, a USB driver is required for CDC. This driver is included in installations
of MPLAB® X IDE.
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 permissions to access the CDC.
On MAC machines, the CDC will enumerate and appear as /dev/tty.usbmodem#. Depending on which terminal
program is used, it will appear in the available list of modems as usbmodem#.
© 2020 Microchip Technology Inc.
User Guide
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4.1.2.3 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.
4.1.2.4 Signaling
During USB enumeration, the host OS will start both 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.
When a terminal connects on the host, it must assert the DTR signal. 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 then 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, so no further data will be transferred to the host computer
• Debugger UART transmitter will continue to send data that is queued for sending, but no new data is accepted
from the host computer
• Level shifters (if available) are not disabled, so 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, so no further data will be transferred to the host computer
• Debugger UART transmitter will continue to send data that is queued for sending, but no new data is accepted
from the host computer
• Once the ongoing transmission is complete, level shifters (if available) are disabled, so the debugger CDC TX
line will become high-impedance
PIC18F16Q41 Curiosity Nano
Curiosity Nano
Info: For all operating systems: Be sure to use a terminal emulator that supports DTR signaling. See
4.1.2.4 Signaling.
Remember: Set up the terminal emulator to assert the DTR signal. Without the signal, the on-board
debugger will not send or receive any 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 during power-up, these lines are floating. To avoid any glitches resulting in
unpredictable behavior like framing errors, the target device should enable the internal pull-up resistor on
the pin connected to the debugger’s CDC TX pin.
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User Guide
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4.1.2.5 Advanced Use
CDC Override Mode
In normal 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 must 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 has been configured,
the previously used baud rate still applies
Debugger firmware version 1.21 and later has the following limitations/features:
• The maximum message length may 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 of
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=
PIC18F16Q41 Curiosity Nano
Curiosity Nano
The CDC Override Mode should not be used simultaneously with data transfer over the CDC/terminal. If a CDC
terminal session is active at the time a file is received via 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, which will be chunked into 64-byte USB
frames. Each such frame will be queued up for sending to the debugger’s CDC TX pin. Transferring a small amount
of data per frame can be inefficient, particularly at low baud rates, as the on-board debugger buffers frames and 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.
If the host (or the software running on it) fails to receive data fast enough, an overrun will occur. When this happens,
the last-filled buffer frame will be recycled instead of being sent to the USB queue, and a full data frame will be lost.
To prevent this occurrence, the user must ensure that the CDC data pipe is being read continuously, or the incoming
data rate must be reduced.
4.1.3 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
© 2020 Microchip Technology Inc.
User Guide
DS50003048A-page 11
• Write access for programming Intel® HEX formatted files into the target device’s memory
• Write access for simple text files for utility purposes
4.1.3.1 Mass Storage Device Implementation
The on-board debugger implements a highly optimized variant of the FAT12 file system that has 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
that can be found in the disk drives section of the device manager. The CURIOSITY drive appears in the file manager
and claims the next available drive letter in the system.
The CURIOSITY drive contains approximately one MB of free space. This does not reflect the size of the target
device’s Flash in any way. When programming an Intel® HEX file, the binary data are encoded in ASCII with
metadata providing a large overhead, so one MB is a trivially chosen value for disk size.
It is not possible to format the CURIOSITY drive. When programming a file to the target, the filename may appear in
the disk directory listing. This is merely the operating system’s view of the directory, which, 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 application that has been previously programmed.
To erase the target device, copy a text file starting with “CMD:ERASE” onto the disk.
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
PIC18F16Q41 Curiosity Nano
Curiosity Nano
Info: STATUS.TXT is dynamically updated by the on-board debugger. The contents may be cached by
the OS and, therefore, do not reflect the correct status.
4.1.3.2 Configuration Words
Configuration Words (PIC® MCU Targets)
Configuration Word settings included in the project being programmed after program Flash is programmed. The
debugger will not mask out any bits in the Configuration Words when writing them, but since it uses Low-Voltage
Programming mode, it is unable to clear the LVP Configuration bit. If the incorrect clock source is selected, for
example, and the board does not boot, it is always possible to perform a bulk erase (always done before
programming) and restore the device to its default settings.
4.1.3.3 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 4-2. Special File Commands
Command Content Description
CMD:ERASE
CMD:SEND_UART=
Executes a chip erase of the target
Sends a string of characters to the CDC UART. See “CDC
Override Mode.”
© 2020 Microchip Technology Inc.
User Guide
DS50003048A-page 12
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