Manufacturing an Arduino R4


My journey with the Arduino PCB’s began a year ago when I purchased Chinese K40 Laser cutter and engraver from EBay which I upgraded with a Grbl controller based on the UNO R4. After experimenting with a stock Arduino UNO R3, I decided that I needed a better Arduino with at least one additional 16 bits PWM channel without an added price tag. Since I am controlling a CO2 laser, speed or additional processing power are not a requirement since the CO2 gas needs time to ionize and quality engraving takes time. Throwing in a huge ARM processor on 80MHz is not going to make a huge difference.

I did find a good candidate in the 328PB which is a more powerful sibling processor because of its extended features (additional ports, two additional 16bit timers, 2 USART’s) and it’s actually cheaper as well.

Atmega328PB Atmega328
Unique Device ID
2* Serial Interface 1* Serial Interface
2* SPI 1* SPI
2* I²C/TWI 1* I²C/TWI
27* Digital IO 23* Digital IO
3* 16Bit Timer 1* 16Bit Timer
10 PWM Channel (PD2 double used) 6 PWM Channel
Clock Failure Detection
Waveform Generator
USART Sleep Mode Wake up

Since I could not find any new Arduino boards based on the 328PB, I decided to make my own R4 based on a R3 board. My first attempt was using a stock Arduino board and carefully removing its current Atmega 328 processor and soldering in a new advanced Atmega 328PB. Unfortunately, it did not work so I had a second attempt with another board which failed as well. I could program it but that was it, no ‘hello’ life sign from Grbl when starting it up. After carefully reading the Datasheet, I discovered that the manufacturer removed the so-called ‘full swing oscillator’ clock circuit in order to make room for the additional features and that the chip needed a high performance crystal rather than the cheap crystals or RC based circuits that are being utilised in the current clone Arduino boards.

Having little experience with surface mounted devices, I decided to take the designed the board to PCBway, a Chinese manufacturer of PCBs. They did the whole manufacturing job of my ten boards from PCB to SMD assembly for me. Unfortunately, I made a few mistakes in selecting the components from an online components catalogue, like a reset button which was too small in size and a wrong model header but that was easy to rectify by myself. It shows you never can rely on catalogues alone.

All ten boards worked immediately after installing Grbl! PCBway did a truly excellent job and the quality and finish is definitely professional. I could not tell this apart from the boards that I buy from commercial suppliers. Bella from PCBway did a great job in communicating with me during the production process and she even followed up after they delivered the boards via DHL.

Now I can use the CNC firmware Grbl on my laser and do 16 bits engraving. Can’t be happier and more satisfied!

4 thoughts on “Manufacturing an Arduino R4”

    1. Looked at the Leonardo but couldn’t get the grbl code to work properly. I had already experience with the Mega but stummbled into the atmega-328pb version and couldn’t resist to try it first. The port was extremely simple and easy (similar as the Mega). I just have been looking into the SAMD2G18 processor which might be actually a great candidate as well. Also the UNO format gives access to other shields and maybe people are just interested in the R4 for something else.

  1. I am very interested in your experiences with PCBway. Could you give some more details? How long did it take in the end from sending the first files to receiving the final boards? How much did it cost? How to they calculate the part prices? Something like “digikey +10% handling fee” or do they have a special list?

    And do you know about this R4 board? It was introduced mid-2016 and should be available with several distributers:

    1. Hi Michael, PCBs probably take a week. They sent it by courier so you really get it fast after manufacturing. Assembly takes up to 2 weeks. I got PCBway to buy to components which was 50% more expensive than sourcing it myself. They do sent you the remainder of the parts (leftover parts). You can do an online quote based on the number of smd and thru hole components.Send your BOM and they will advise the cost.
      I have seen the Elektor R4 which is a bit expensive for Australia (postage kills it). A cheaper alternative is the Mini Xplained 328PB from AVR. You can get them around $14. Just add a USB break out board to use the 2nd uart or reroute the exisiting one if you are brave! I use a USBASP to program them.

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