Microchip Technology ATMEGA168PB-XMINI User manual

ATmega168PB Xplained Mini
ATmega168PB Xplained Mini
Preface
This user guide describes how to get started with the ATmega168PB Xplained Mini evaluation kit. The
evaluation kit is a hardware platform to evaluate the ATmega168PB microcontroller. The on-board mini
embedded debugger provides seamless integration with Atmel Studio. The kit provides access to the
features of the ATmega168PB enabling easy integration of the device in a custom design.
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 1

Table of Contents
Preface............................................................................................................................ 1
1. Introduction................................................................................................................4
1.1. Features....................................................................................................................................... 4
1.2. Board Overview............................................................................................................................4
2. Getting Started.......................................................................................................... 6
2.1. Xplained Mini Quick Start............................................................................................................. 6
2.2. Design Documentation and Related Links................................................................................... 6
2.3. Programming and Debugging...................................................................................................... 6
2.3.1. Programming the Target Using mEDBG........................................................................6
2.3.2. Debugging the Target Using mEDBG............................................................................8
2.3.3. Programming the Target Using an External Programmer..............................................9
2.3.4. Programming the ATmega32U4 Using an External Programmer..................................9
2.3.5. Programming the ATmega32U4 Using a Bootloader...................................................10
3. Xplained Mini........................................................................................................... 11
3.1. Mini Embedded Debugger..........................................................................................................11
3.1.1. Xplained Mini Clock Output..........................................................................................11
3.2. mEDBG Configuration................................................................................................................12
3.2.1. mEDBG Low Power Modes.........................................................................................12
3.2.2. mEDBG Fuse Filter......................................................................................................12
3.2.3. mEDBG Command Line Interface............................................................................... 13
3.2.4. Super User Fantastic Feature Enable Register........................................................... 13
3.3. mEDBG Firmware Upgrade and Manual Bootloader Entry........................................................14
4. Hardware User Guide..............................................................................................15
4.1. Power Sources...........................................................................................................................16
4.2. Board Assembly......................................................................................................................... 17
4.2.1. Connecting an Arduino Shield..................................................................................... 17
4.3. Target Headers and Connectors................................................................................................ 17
4.3.1. Target Digital I/O.......................................................................................................... 17
4.3.2. Board Power Header................................................................................................... 18
4.3.3. Target Analogue I/O.....................................................................................................19
4.3.4. Target Programming.................................................................................................... 19
4.3.5. Target Additional I/O.................................................................................................... 19
4.4. Target Peripherals...................................................................................................................... 20
4.4.1. Push Button................................................................................................................. 20
4.4.2. User LED..................................................................................................................... 20
4.5. mEDBG...................................................................................................................................... 21
4.5.1. mEDBG COM Port Connection................................................................................... 21
4.5.2. mEDBG JTAG Interface...............................................................................................21
4.6. Extension Header Area.............................................................................................................. 22
4.7. Factory Programmed..................................................................................................................23
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 2

5. Hardware Revision History and Known Issues........................................................24
5.1. Identifying Product ID and Revision........................................................................................... 24
5.2. Revision 5...................................................................................................................................24
6. Document Revision History..................................................................................... 25
The Microchip Web Site................................................................................................ 26
Customer Change Notification Service..........................................................................26
Customer Support......................................................................................................... 26
Microchip Devices Code Protection Feature................................................................. 26
Legal Notice...................................................................................................................27
Trademarks................................................................................................................... 27
Quality Management System Certified by DNV.............................................................28
Worldwide Sales and Service........................................................................................29
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 3

1. Introduction
1.1 Features
The ATmega168PB Xplained Mini evaluation kit provides a development platform for the ATmega168PB.
Key Features
• On-board debugger with full source-level debugging support in Atmel Studio
• Auto-ID for board identification in Atmel Studio
• Access to all signals on the target MCU
• One green mEDBG status LED
• One yellow user LED
• One mechanical user push button
• Virtual COM port (CDC)
• External target CLK 16MHz at 5V, 8MHz at 3.3V
• USB powered
• 3.3V regulator
• Arduino shield compatible footprints
• Target SPI bus header footprint
• Xplained Pro extension headers can easily be strapped in
1.2 Board Overview
A brief overview of the default kit configuration, headers, and connectors.
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 4

Figure 1-1. ATmega168PB Xplained Mini Headers and Connectors
Digital I/O Low (J201)
Digital I/O Hi gh (J200)
Power (J202)
Analog I/O (J203)
PC4
PC5
ATmega168PB
Power
Ground
Target I/O
Shared I/Os
PC3
PC2
PC1
PC0
VIN
GND
5V
GND
3V3
RESET
VCC
NC
PD0
PD1
PD2
PD3
PD4
PD5
GND
PD6
PD7
PB0
PB1
PB2
PB3
PB4
PB5
AREF
PC4
PC5
LED / ISP (J204)
CDC TX
CDC RX
External
Clock
SPI
(J204)
CDC UART
(J104)
mEDBG
(ATmega32U4)
Power source
(J300)
Micro USB
Con nector
Target power
(J301)
Status
LED
PB5PB7
User
LED
User
button
ISP (J204)
ISP (J204)
ANALOG (J203)
ANALOG (J203)
DIGITAL J200
DIGITAL J200
Table 1-1. Default Configurations
Function Default configuration Other settings
Kit power source (J300) 5.0V USB powered External input VIN (1)
Target power (J301) 5.0V USB powered 3.3V from the on-board regulator
(1)
ATmega168PB clock 16MHz mEDBG clock (2)Internal oscillator (3)
Info:
Changing the default settings require modification of the kit using a soldering iron.
1) Details on how to change the power settings are described in Power Sources.
2) Details on the mEDBG clock are described in Xplained Mini Clock Output.
3) Debugging through debugWIRE may be disabled if the internal oscillator is used.
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 5

2. Getting Started
2.1 Xplained Mini Quick Start
Steps to start exploring the Xplained Mini platform:
1. Download Atmel Studio.
2. Launch Atmel Studio.
3. Connect a USB cable (Standard-A to Micro-B or Micro-AB) between the PC and the USB port on
the kit.
When the Xplained Mini kit 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 kit are
included with the Atmel Studio.
Once the Xplained Mini board is powered the green status LED will blink and Atmel Studio will autodetect
which Xplained Mini board is connected. Atmel Studio will present relevant information like data sheets
and kit documentation. The ATmega168PB device is programmed and debugged by the on-board Mini
Embedded Debugger and therefore no external programmer or debugger tool is required.
2.2 Design Documentation and Related Links
The most relevant documents and software for the evaluation kit are available here:
ATmega168PB Xplained Mini website - Kit information, latest user guide, and design documentation.
ATmega168PB Xplained Mini on Microchip Direct - Buy this kit on microchipDIRECT.
•Atmel Studio - Free IDE for the development of C/C++ and assembler code for microcontrollers.
•Xplained products - Xplained evaluation kits are a series of easy-to-use evaluation kits for
Microchip microcontrollers and other Microchip products.
– Xplained Nano: used for low pin-count devices and provides a minimalistic solution with
access to all I/O pins of the target microcontroller.
– Xplained Mini: used for medium pin-count devices and adds Arduino Uno compatible header
footprint and a prototyping area.
– Xplained Pro: used for medium to high pin-count devices that features advanced debugging
and standardized extensions for peripheral functions.
Note: All the above kits have on-board programmers/debuggers, which creates a set of low-cost
boards for evaluation and demonstration of features and capabilities of different Microchip products.
•Atmel Spaces - Open Source projects for Xplained Mini.
•http://start.atmel.com/ - Atmel START is an online tool to help you select and configure software
components and tailor your embedded application in a usable and optimized manner.
2.3 Programming and Debugging
2.3.1 Programming the Target Using mEDBG
Using the Embedded Debugger on the ATmega168PB Xplained Mini board to program the
ATmega168PB.
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 6

1. Connect the Xplained Mini USB to the PC.
2. Go to Atmel Studio: Click the Tools tab, select Device Programming, and select the connected
mEDBG as Tool with Device as ATmega168PB and Interface to ISP, click Apply.
3. Select "Memories", locate the source .hex or .elf file, and click Program.
4. NOTE: If a previous debug session was not closed by selecting "Disable debugWIRE and Close" in
the Debug menu, the DWEN fuse will be enabled and the target will still be in debug mode, i.e. it
will not be possible to program the target using the ISP interface.
5. If the source file contains fuse settings, select "Production file" and upload the .elf file to program
the fuses.
6. Select "Fuses" to program the fuses manually. Set the fuse(s) and click "Program". Recommended
fuse settings:
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 7

2.3.2 Debugging the Target Using mEDBG
Using the Embedded Debugger on the ATmega168PB Xplained Mini board to debug the ATmega168PB
via debugWIRE.
1. Start Atmel Studio.
2. Connect the Xplained Mini USB to the PC.
3. Open your project.
4. Click the "Project" tab and select the project "properties", click the "Tools" tab, and select mEDBG
as debugger and debugWIRE as interface.
5. Click the "Debug" tab and select "Start Debugging and Break".
6. Atmel Studio will display an error message if the DWEN fuse in the ATmega168PB is not enabled,
click YES to make Studio set the fuse using the ISP interface.
7. A debug session is started with a break in main, the debugging can start.
8. To exit debug mode, select "Disable debugWIRE and Close" in the Debug tab. This will disable the
DWEN fuse.
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 8

Info:
If debug mode is not exited by selecting "Disable debugWIRE and Close" in the Debug menu,
the DWEN fuse will be enabled and the target will still be in debug mode, i.e. it will not be
possible to program the target using ISP.
If any other CPU CLK than the external CLK supplied by the mEDBG is used, the debugWIRE
is not guaranteed to work.
Applying a signal to J202/RESET (the RESET_SENSE signal) while debugging may result in
unexpected behavior. This signal is NOT available during a debugging session because the
RESET line is actively used by the debugWIRE interface.
2.3.3 Programming the Target Using an External Programmer
How to program the target ATmega168PB using the AVR® JTAGICE mkII, JTAGICE3, Atmel-ICE, or other
programmers.
1. Connect the External Programmer USB to the PC.
2. Connect the External Programmer to the ATmega168PB Xplained Mini board ISP connector.
3. Go to Atmel Studio: Click the Tools tab, select Device Programming, and select the External
Programmer connected as Tool with Device as ATmega168PB and Interface to ISP, click Apply.
4. Select "Memories", locate the source .hex or .elf file, and click Program.
2.3.4 Programming the ATmega32U4 Using an External Programmer
How to program the ATmega32U4 using the AVR JTAGICE mkII, JTAGICE3, Atmel-ICE, or other
programmers.
1. Connect the External Programmer USB to the PC.
2. Connect the External Programmer to the ATmega168PB Xplained Mini board JTAG connector.
3. Go to Atmel Studio: Click the Tools tab, select Device Programming, and select the connected
mEDBG as Tool with Device as ATmega32U4 and Interface to JTAG, click Apply.
4. Select "Memories", locate the source .hex or .elf file, and click Program.
5. Select "Fuses" to program the fuses manually. Set the fuse(s) and click "Program". Recommended
fuse settings:
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 9

Warning: Changing the firmware in the ATmega32U4 will remove the programming and
debugging capabilities of the mEDBG. If the EEPROM is altered the mEDBG may not be
recognized by Atmel Studio anymore.
2.3.5 Programming the ATmega32U4 Using a Bootloader
This section describes how to use the bootloader to program the ATmega32U4.
1. Launch Atmel Studio.
2. Short strap J102.
3. Open the programming dialog, select the bootloader in the tool menu.
4. Connect the ATmega168PB Xplained Mini board USB connector to the PC.
5. Select Device = ATmega32U4 (Device - Select).
6. Select USB communication (Ctrl+U).
7. Select the memory area to program (use the toggle memory button).
8. Select Load Hex file (Ctrl+L).
9. Select Programming Options.
10. Click "Run", observe the status in the status field.
Warning: Changing the firmware in the ATmega32U4 will remove the programming and
debugging capabilities of the mEDBG. If the EEPROM is altered the mEDBG may not be
recognized by Atmel Studio anymore.
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 10

3. Xplained Mini
Xplained Mini is an evaluation platform that provides a set of small boards with access to all
microcontroller I/Os. The platform consists of a series of low-pin-count Microcontroller (MCU) boards,
which are integrated with Atmel Studio to present relevant user guides, application notes, datasheets,
and example code. The platform also features a Virtual COM port for serial communication to a host PC.
3.1 Mini Embedded Debugger
The ATmega168PB Xplained Mini contains the Mini Embedded Debugger (mEDBG) for on-board
programming and debugging. The mEDBG is a composite USB device of two interfaces; a debugger and
a Virtual COM Port.
Together with Atmel Studio, the mEDBG debugger interface can program and debug the ATmega168PB.
On ATmega168PB Xplained Mini, the ISP/dW interface is connected between the mEDBG and the
ATmega168PB.
The Virtual COM Port is connected to a UART on the ATmega168PB and provides an easy way to
communicate with the target application through the terminal software. It offers variable baud rate, parity,
and stop bit settings.
Note: The settings on the ATmega168PB must match the settings given in the terminal software.
Info: The virtual COM port in the mEDBG requires the terminal software to set the data
terminal ready (DTR) signal to enable the UART pins connected to the ATmega168PB. If the
DTR signal is not enabled the UART pins on the mEDBG are kept in high-z (tri-state) rendering
the COM port unusable. The DTR signal is automatically set by some terminal software, but it
may have to be manually enabled in your terminal.
The mEDBG controls one status LED on the ATmega168PB Xplained Mini. The table below shows how
the LED is controlled in different operation modes.
Table 3-1. mEDBG LED Control
Operation mode Status LED
Power up LED is briefly lit
Normal operation LED is not lit
Programming Activity indicator; the LED flashes when
programming/debugging with the mEDBG
3.1.1 Xplained Mini Clock Output
The mEDBG outputs its CPU clock on a pin. This clock pin is connected to the ATmega168PB clock input
and is used to have a synchronous clock with the mEDBG to enable debugging through debugWIRE.
To disconnect the external clock to the ATmega168PB a 0Ω resistor or strap has to be removed from the
footprint, as shown in the figure below (R109).
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 11

Figure 3-1. External Clock Footprint
The mEDBG CPU clock frequency depends on the selected voltage, see the table below.
Table 3-2. CPU Clock vs. Voltage
Target voltage mEDBG CPU clock
3.3V 8MHz
5.0V 16MHz
3.2 mEDBG Configuration
The operation of the mEDBG can be configured by writing registers in the mEDBG. No configuration is
required for default operation.
3.2.1 mEDBG Low Power Modes
There are two modes that enable the mEDBG to save power when connected to an external power
source.
EOF mode, where the mEDBG is disabled. When enabled the ATmega32U4 will enter sleep mode if the
USB does not enumerate within 5 seconds of power-up. In this mode, the external clock is not available
to the target MCU.
LOWP mode, where the mEDBG is set to run at 1MHz. Saving power while maintaining the USB
connection for the COM port. The external clock will be 1MHz.
Table 3-3. Low Power Modes Operation
Mode External CLK COM port ISP/dW program ISP/dW debug
EOF disabled disabled disabled disabled
LOWP forced 1MHz enabled useless useless
Factory settings enabled enabled enabled enabled
3.2.2 mEDBG Fuse Filter
The mEDBG does not initially allow users to program all fuses of the target device through Atmel Studio,
as a filter is implemented to protect certain fuses. The protected fuses are different for every product
using the mEDBG and are typically clock related fuses that could be set to invalid configurations.
The fuse protection can be disabled by writing the FUSE bit to 0.
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 12

Info: The fuse filter prevents users from changing critical fuses using Atmel Studio; however, it
does not prevent users from setting fuses freely using the command line interface atprogram
bundled with Atmel Studio.
3.2.3 mEDBG Command Line Interface
The configuration of the mEDBG can be changed using a simple command line interface available on
Atmel Spaces Releases (mEDBG_script.zip).
The CLI is written for Python® 2.7 and may work on other Python 2.x versions. Python can be
downloaded from Python.
The CMSIS-DAP commands used by the CLI are not supported in early mEDBG firmware versions. To
upgrade the firmware, download the latest version of Atmel Studio and connect to the mEDBG with the
programming dialog.
The register definitions are available in the following sections.
Related Links
SUFFER
3.2.4 Super User Fantastic Feature Enable Register
The Super User Fantastic Feature Enable Register allows the user to modify the behavior of the mEDBG.
Name: SUFFER
Offset: 0x0120
Reset: 0xFF
Property: N/A
Bit 7 6 5 4 3 2 1 0
EOF LOWP FUSE
Access R/W R/W R/W
Reset 1 1 1
Bit 2 – EOF: Extended Off
Writing the EOF bit to 1 sets default operation. Writing the EOF bit to 0 enables the extended off power
mode. If no USB enumeration is successful within five seconds of power up, the mEDBG enters deep
sleep.
Bit 1 – LOWP: Low Power
Writing the LOWP bit to 1 sets the system clock to its default value. Writing the LOWP bit to 0 enables
low power mode. The mEDBG is set to run at 1MHz, which decreases the power usage.
Bit 0 – FUSE: FUSE Protection
Writing the FUSE bit to 1 enables fuse protection when using Atmel Studio. The fuse protection prevents
modification of specific fuses in the ATmega168PB target device that could make the mEDBG on the
ATmega168PB Xplained Mini not usable. Writing the FUSE bit to 0 removes all protection of fuses in the
ATmega168PB target device.
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 13

Warning: Writing the FUSE bit to 0 enables modification of all fuses in the ATmega168PB.
Setting wrong fuse settings may render the mEDBG not usable on the ATmega168PB Xplained
Mini. As an example; if an invalid clock setting is set, a recovery may require an external
debugger.
3.3 mEDBG Firmware Upgrade and Manual Bootloader Entry
The mEDBG firmware is updated through the programming dialog in Atmel Studio.
If you are unable to upgrade the mEDBG firmware on your ATmega168PB Xplained Mini, you can try the
command line utility atfw.exe provided with the Atmel Studio. atfw.exe is located in the atbackend folder in
your Atmel Studio install location.
To manually upgrade the firmware, run the following command:
atfw.exe -t medbg -a ..\tools\ mEDBG\medbg_fw.zip
If atfw.exe is unable to find the mEDBG it may be required to force the ATmega32U4 (mEDBG) to enter
its bootloader. To force the bootloader entry, short-circuit the BOOT pads (J102) and toggle power to the
ATmega168PB Xplained Mini board. Run the atfw command above. When the firmware is upgraded,
remove the power from the kit and remove the short-circuit of J102.
Figure 3-2. Force Boot Jumper
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 14

4. Hardware User Guide
The following sections describe the implementation of the relevant peripherals, headers, and connectors
on the ATmega168PB Xplained Mini and their connections to the ATmega168PB. The tables of
connections in the sections below also describe which signals are shared between the headers and on-
board functionality.
The figure below shows the assembly drawing of the ATmega168PB Xplained Mini to help identification of
components.
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 15

Figure 4-1. ATmega168PB Xplained Mini Assembly Drawing
4.1 Power Sources
The ATmega168PB Xplained Mini kit can be powered by a USB or an external voltage input VIN. The
default power source is 5.0V from a USB. The USB port is protected with a 500mA PTC resettable fuse.
The ATmega168PB is powered from the 5.0V USB voltage by default.
The figure below shows the possible kit power supply connections.
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 16

Figure 4-2. Power Supply Block Diagram
Power source Power swit chPower converter Power consumer
External input
5V
mEDBG USB
Regulator 3.3V
Input select
jumper
0R
VCC_P5V0 Target select
jumper
0R
mEDBG
&
Target
VCC_P5V0
VCC_P3V3
The input voltage select jumper (J300, 3-pin header footprint) can be soldered in to select between power
from the USB port or from the VIN pin on the Arduino power header footprint. By default, the selector is
bypassed with a 0Ω resistor (R300) to connect the USB voltage to the on-board 3.3V/150mA regulator
and target voltage select header.
The target voltage select jumper (J301, 3-pin header footprint) can be soldered in to select between the
on-board 3.3V regulator or the voltage from the input voltage select jumper (J300). The selector is
bypassed with a 0Ω resistor (R301) to connect the kit input voltage to the ATmega168PB and mEDBG.
Important: If the target voltage and input voltage select headers are soldered in and used with
a jumper, the bypass 0Ω resistors have to be removed to avoid contention.
4.2 Board Assembly
The Xplained Mini board can easily be assembled into a product prototype for software development and
hardware verification. All signals of the ATmega168PB are available in the Xplained Mini board connector
grid, enabling easy connection of external sensors and output devices in order to prototype the customer
specific application.
4.2.1 Connecting an Arduino Shield
Arduino® shields can be mounted in the marked positions (J200, J201, J202, J203, and J204).
Warning: The ATmega168PB Xplained Mini connects VCC_TARGET to the Arduino SPI
connector, while all Arduino boards connect VCC_P5V0 to the same pin. The VCC_TARGET
may be either 3.3V or 5.0V depending on the configuration of the kit if the kit is configured for
3.3V operation. Connecting an Arduino shield may damage the board permanently. It is not
recommended to solder the SPI connector when using Arduino shields if not strictly necessary.
If the connector is required it is recommended to remove pin two from the SPI connector.
4.3 Target Headers and Connectors
4.3.1 Target Digital I/O
The J200 and J201 headers provide access to the ATmega168PB digital I/O pins.
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 17

Table 4-1. J200 Digital I/O High Byte Header
J200 pin ATmega168PB pin Function
1 PB0
2 PB1
3 PB2 SS, SPI Bus Master Slave select
4 PB3 MOSI, SPI Bus Master Output/Slave Input
5 PB4 MISO, SPI Bus Master Input/Slave Output
6 PB5 SCK, SPI Bus Master clock Input
7 GND
8 AREF
9 PC4 SDA, 2-wire Serial Bus Data Input/Output Line. Shared with
ADC4.
10 PC5 SCL, 2-wire Serial Bus Clock Line. Shared with ADC5.
Table 4-2. J201 Digital I/O High Low Header
J201 pin ATmega168PB pin Function
1 PD0 RXD (ATmega168PB USART Input Pin)
2 PD1 TXD (ATmega168PB USART Output Pin)
3 PD2
4 PD3
5 PD4
6 PD5
7 PD6
8 PD7
4.3.2 Board Power Header
The J202 header enables connection to the ATmega168PB Xplained Mini power system.
Table 4-3. J202 Power Header
J202 pin Signal Description
1 NC
2 VCC_TARGET The power source selected for the target (select by J301)
3 RESET_SENSE This is a RESET signal monitored by the mEDBG. If pulled low the
target RESET line will be pulled low by the mEDBG. The ATmega32U4
internal pull-up is enabled. This signal is not available during debugging.
4 VCC_P3V3 The 3.3V regulator output
5 VCC_P5V0 The selected power source (VIN or VBUS selected by J300)
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 18

J202 pin Signal Description
6 GND
7 GND
8 VCC_VIN The external power source connection (connected to J300 pin 3)
4.3.3 Target Analogue I/O
The ATmega168PB ADC input pins are available in the J203 header.
AREF is available in J200 pin 8.
Table 4-4. J203 Analogue Header
J203 pin ATmega168PB pin Function
1 PC0 ADC Input Channel 0
2 PC1 ADC Input Channel 1
3 PC2 ADC Input Channel 2
4 PC3 ADC Input Channel 3
5 PC4 ADC Input Channel 4
6 PC5 ADC Input Channel 5
4.3.4 Target Programming
The J204 header enables direct connection to the ISP bus with an external programmer for programming
of the ATmega168PB.
Table 4-5. SPI Header
J204 pin ATmega168PB pin Function
1 PB4 MISO
2 VCC target
3 PB5 SCK
4 PB3 MOSI
5 PC6 RESET
6 GND
4.3.5 Target Additional I/O
Signals not available in any of the headers or connectors are available in column 5 of the grid.
Table 4-6. Additional I/O
ATmega168PB pin Grid position
PE01 J5
PE02 I5
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 19

ATmega168PB pin Grid position
PE03 H5
PE04 G5
4.4 Target Peripherals
The ATmega168PB Xplained Mini has one LED and one push button.
Figure 4-3. ATmega168PB Xplained Mini Peripherals
4.4.1 Push Button
A general purpose push button, SW200, is connected to PB7.
Figure 4-4. User Button
PB7
1 3
42
SKRAAKE010
SW200
GND
100k
R209
VCC_TARGET
100n
C204
USER BUTTON
4.4.2 User LED
There is one yellow LED, D200, available for use by the application SW.
The LED is connected to ATmega168PB pin 17 - PB5, the SCK signal from the mEDBG is in 3-state
when not used.
ATmega168PB Xplained Mini
© 2017 Microchip Technology Inc. User Guide DS50002636A-page 20