Before you order, please read the whole description, the price will change based on selected option:

• PCB - $1
• PCB + components + $10
• PCB + assembled components + 15$

In case of assembly you pay for my time assembling and testing, if you like to solder/learn to solder then KIT is for you, if you just like to use it, then fully assembled unit is for you.

Each board is hand assembled, no pick and place, this is why it is not so cheap.

What is it?

Bare PCB/kit/fully assembled board (check options on right) for Atmega328PB(P/PA compatibility via solder jumpers) with Arduino Uno compatible pinout. For USB to serial conversion CP2102N QFN24 version (pinout compatible with CP2104) chip is used, this is required only if you wanna use upload over USB(with bootloader), if ICSP is used then this chip does not have to be soldered. This board also has 6pin header which is compatible with cheap USB to serial boards.

ATmega328PB chip has two more pins (PE0 and PE1), in Arduino environment these pins are D23 and D24, these pins are routed out on place of I2C next to AREF pin, this is because PE0 and PE1 are second I2C port also.(SDA1,SCL1). Pins A6 and A7 are more than just analog inputs (PE2 and PE3). In case of using any other version of atmega328 then PB, there are 4 jumpers witch when set according manual will connect everything as on original arduino uno board.

Enhancement and Additional Features in ATmega328PB

Compared to existing ATmega328 variants, the following enhancements or additional features are available in ATmega328PB: • PTC - Peripheral Touch Controller. • CFD - Clock Failure Detection mechanism. • OCM1C2 - Output Compare Modulator. • USART start frame detection is available in all sleep modes • Analog Comparator output is available on a pin. This pin is multiplexed with PE0. • Unique device ID to identify the device • Additional USART • Additional SPI • Additional TWI • Additional Timer/Counters

For more information about difference between 328 chips check this PDF on microchip website.

Why did you make it?

I was in need for drop in replacement for arduino nano with more functionality (pins, UARTs, I2C...) , so I made a few boards for a few different/updated chips and while I was playing with this I designed more than what i needed (I mostly use breadboard compatible version). I designed this set of boards:

• Atmega328P/PA/PB board compatible with Arduino nano
• Atmega328P/PA/PB board compatible with Arduino Uno
• Atmega324P/PA board compatible with Arduino nano (PB version not produced yet, only designed, check github)
• Atmega324P/PA board compatible with Arduino mega (PB version not produced yet, only designed, check github)
• Atmega2560 board compatible with Arduino mega with all pins routed to pinheaders

What makes it special?

• support for PB version of ATmega328 (4 more IO)
• better usb to serial chip(CP2102N) then on chines clones
• support for 3 diferent USB sockets (2version of micro, 1 USB B connector)
• 6pin header which accept CP2102 usb to serial adapter from china
• still open source

Arduino support

To use PB version of ATmega328 chip with arduino IDE you need to install MiniCore from MCUdude: https://github.com/MCUdude/MiniCore.

Selecting PB/nonPB version of installed chip

On board are 5 jumpers:

• 2 are 3pads jumpers (JP4, JP5): these are used to select where are PE0 and PE1 connected depending on which chip is used, in case of PB version pins closer to digital pins need to be soldered, in case of none PB chip, pins closer to analog pins need to be soldered.
• 2 are 2pins jumpers (JP1,JP2): these are used to route A5/A6(I2C) to SCL/SDA pins near AREF used in case of none PB chip is installed

Order options:

• PCB - bare PCB
• KIT - PCB + parts, nothing is soldered, chip is not programed with any sort of bootloader
• Assembled - fully assembled product, tested, chip is programed with optiboot bootloader from Minicore repository

Bare PCB.

kit option. Download assembly plan here.

Assembled unit

Why not RX/TX leds?

There is a place for RX/TX leds on PC (unpopulated R5,R6,D3 and D4), but I made error in design and route them to ground, they should be connected to 5V rail. I was about to run new PCBs when I realize that it is not important to me, and it can be simply fixed with 1 wire.

Opensource

All design files are on github in my personal HW repository.

Problems, suggestions

I created this for my needs, and as I have spare boards I sell them, all files are available to check before order, all bugs are mentioned here, but in case anything new pops up, drop me email or send message on product page, I do my best to resolve any issue or talk about any suggestions. But if you are skilled in github ecosystem and have an account there feel free to fill an issue there, do not forget to mention that you are talking about unoPB :).