Central Unit 2.0

Although my central unit 1.x is still up-to-date, I made an update to a version 2.0. The main differences are the housing from Hammond (I believe it’s easier to source worldwide) and the option for a dual-RTK. Furthermore, there is a section control board, that can easily combined to it.

The hardware structure is pretty much the same as in version 1.x, and so Brian’s Nano firmware will hopefully run out of the box:

An Ardusimple-board can be added as piggyback.

In case, dual-RTK is intended, just add a second Ardusimple-board. In that case, an additional ESP32 with MTZ’s firmware (with some minimal mods for port assignment) is needed. Nothing exiting - more a proven-in-use approach.

If you like to split into steering and GNSS units (single, dual and/or with IMU), you may do: Just use two PCBs, one for steering and one for GNSS.

With software adaptations, it will be possible to use UDP via the ESP32 as well. The ESP is the only USP sink in that case and has to forward the information for autosteering to the Nano (or take over the control completely). Optionally, it has to forward the data to the SC as well. Anyway just a few bytes and no big deal. Diagram in that case:

WiFi comes with the ESP; for Ethernet via cable, the W5500 must be mounted.

As always, data and further information can be found on my Github account. I’m aware, that the doc isn’t perfect at all, but I’m working on it.

Here’s an image of the top side. It shows M8/M12 connectors, but a 24pole PushIn-Option is also provided (same for the V3.0 board). Up to you…


In the meantime, the V2.0 arrived as well. :sunglasses:

The board fits into the Hammond housings 1455L1601 (on the right in the picture) or 1457L1602 (waterproof) including the two Ardusimple boards.

LED colors:

  • green and blue for communication
  • yellow and orange for mixed signals
  • red for errors
  • white for power presence

Status so far:

  • autosteer works with version 5.4.5 out of the box including WAS, IMU and power driver (ICs difficult to buy right now) and Danvoss (no prob)
  • USB including hub and single Ardusimple board ok
  • ESP32 works (as LOLIN D32) as dual-RTK-receiver with the firmware from MTZ8302 and two Ardusimple boards.
  • Ethernet via W5500 and WiFi tested now

As always, please mind latestest information provided in the changelog file.. Issues mentioned there are already solved with the latest data in production data folder.


Attempted to order this today. There is already 12 inventory shortages

I know - that sucks… And the procurement of my company doesn’t expect a significant improvement this year… :grimacing: But JLCPCB has a components pre-order function. Didn’t test that, but nice idea.

When attempting to purchase these from JLC there are some parts that currently are on inventory shortage. These are the first 12 lines listed below. Gorm offered to help us get some alternatives to these while these shortages plague us all. In addtion you will notice some parts that the “end user” will need to provide.

I hope to order some of these PCB’s asap. If anyone wants to bulk order PCB’s with me please let me know, else you can order them directly from JLC.

Once I get them I will work with some folks from the community to see if we can get a sketch for the enclosure put toghether. More to follow but it feels like we get closer and closer to getting a hardware solution that doesnt require users to build boards and at home solder.

If you have time I would encourage everyone to “buy a coffee” on this site. This money helps fund development as a few put many hours into this project and many put in a few hours. Helping fund development is the least we all can do.

Looking forward to “driving” in 2022…

Designator Name (ext) Footprint Quantity
USB-B A2541WV-5P (EXT) HDR-TH_5P-P2.54-V-M 1
F+5V RED (MOD) LED0603-FD 1
U10 BTN8982TAA (EXT) TO-263-7_L10.2-W10.4-P1.27-LS14.4-B 1
C65,C66,C67 10UF 25V (MOD) C0805 3
C28,C29,C31 10UF 25V (MOD) C0805 3
R7,R16,R33 1K (MOD) R1206 3
U9 BTN8982TAAUMA1 (EXT) TO-263-7_L10.2-W10.4-P1.27-LS14.4-B 1
C250 22UF 25V (MOD) C0805 1
3V3,5V,12V WHITE (MOD) LED0603-R-RD 3
H3,H2,H4,H5,H11,H12 A2541WV-5P (EXT) HDR-TH_5P-P2.54-V 6
U2,U14 BTS50301EJAXUMA1 (EXT) PG-DSO-8_L4.9-W3.9-P1.27-LS6.0-BL-EP 2
Provided by User
U300 BNO085 (EXT) BNO085 1
USBC1 TYPE-C-31-M-12 (EXT) USB-C_SMD-TYPE-C-31-M-12 1
D5 SMCJ5.0A (EXT) SMC_L6.9-W5.9-LS7.9-RD 1
C202 100NF 50V (MOD) C0603 0
U15 CMPS14 (EXT) CMPS14 1
Comment Designator Name (ext) Footprint Quantity
all A2541WV-…: simple pin row - mount yourself, if you need that USB-B A2541WV-5P (EXT) HDR-TH_5P-P2.54-V-M 1
weird - seems not available any more; many alternatives, e. g. C497918 F+5V RED (MOD) LED0603-FD 1
problematic part! Buy e. g. from Aliexpress U10 BTN8982TAA (EXT) TO-263-7_L10.2-W10.4-P1.27-LS14.4-B 1
many, e. g. C89831 C65,C66,C67 10UF 25V (MOD) C0805 3
many, e. g. C89831 C28,C29,C31 10UF 25V (MOD) C0805 3
many, e. g. C52199 R7,R16,R33 1K (MOD) R1206 3
problematic part! Buy e. g. from Aliexpress (same as above) U9 BTN8982TAAUMA1 (EXT) TO-263-7_L10.2-W10.4-P1.27-LS14.4-B 1
many, e. g. C2922481 C250 22UF 25V (MOD) C0805 1
same as (F+5V) REV RED (MOD) LED0603-R-RD 1
many, e. g. C158100 3V3,5V,12V WHITE (MOD) LED0603-R-RD 3
see above - do yourself H3,H2,H4,H5,H11,H12 A2541WV-5P (EXT) HDR-TH_5P-P2.54-V 6
no chance - sorry… but only needed for hydraulic switching valve U2,U14 BTS50301EJAXUMA1 (EXT) PG-DSO-8_L4.9-W3.9-P1.27-LS6.0-BL-EP 2
external module - buy separately U3 ARDFRUIT BNO085 (EXT) ADAFRUIT-BNO085 1
M12 - buy separately (link in my Git) POWER M12A 5POLE MALE (EXT) M12-A MALE 4-5POLE 90掳 1
external module - buy separately U300 BNO085 (EXT) BNO085 1
not needed any more (Brian added current input in Atmel code) R28 3296W-1-103 (EXT) RESISTOR ADJUSTABLE BOURNS 3296W TH 1
2nd source e. g.: C2346 USBC1 TYPE-C-31-M-12 (EXT) USB-C_SMD-TYPE-C-31-M-12 1
M12 - buy separately (link in my Git) INPUTS,STEERING M12A 5POLE FEMALE (EXT) M12-A FEMALE 4-5POLE 90掳 2
this is no part PT1 TESTPOINT (EXT) TESTPOINT 1
many, e. g. C224055 D5 SMCJ5.0A (EXT) SMC_L6.9-W5.9-LS7.9-RD 1
M8 - buy separately (link in my Git) CAN,IMU,RS485,WAS M8 4POLE FEMALE (EXT) M8 FEMALE 4POLE 90掳 4
many, e. g.: C88476 C202 100NF 50V (MOD) C0603 0
external module - buy separately ARDUSIMPLE1 U10 (EXT) ARDUSIMPLE_MECH_FLIPPED 0
external module - buy separately ARDUSIMPLE2 U11 (EXT) ARDUSIMPLE_MECH_FLIPPED 0
external module - buy separately U15 CMPS14 (EXT) CMPS14 1

All in all it seems that many “basic parts” changed at JLC. Please look out for “basic” alternatives to safe money.

Board update to V2.2 done…

Main feature: Support of TI’s RS485-over-power-bus, so that devices like IMUs can be connected via a jerk-proof two-wire bus with power and data. The wires may even be mixed.

There is an external IMU as well:

PCB data is in this Git folder.

Suggested housing is Hammond Mfg, 1590LLBFL.


Watching this closely as I had built three V1.4 boards and home-soldered the tiny FE1.1s chips on and as it turns out only 1 board/USB hub is a success :grimacing: But as I understand none of that difficulty level in this list?

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unfortunately the pinning is quite dense… you have a microscope (camera)? that helps a lot. and desoldering wire. Can tell you that is particular chip is not the problem right now, but that doesn’t help you too much. Keeping fingers crossed!

What difficulty level?

I had a final go at them and removed all previous solder work and redid them with solder paste and a hot air gun. What a relief! Half hour work for 2 chips and everything working… so it was due to messy hand-soldering although everything looked OK. Thank you for your help :+1:

I discovered that a smartphone like a Galaxy S20FE has very good optical zoom/microscope, it helped to detect/check bridges and soldering quality.


quick status update: tested ESP32 part completely now, so I can say, that the hardware is able to do dual-RTK and autosteer with just the ESP32 as a single-µC solution.


License update done to Cern-OpenHardwareLicense-S-2.0 to keep the project open for everyone in the future. Everyone is allowed to copy and produce everything of this project, but has to open her/his mods for the community.

background information here


In JLCPCB I am getting the following error;


am I missing something?
must I choose some parts and delete their alternatives?

Currently, in JLCPCB, only 1 part is out of stock. But Atmega Processor and Motor Drives are ridiculously expensive. They charge $60 for an Atmega and $30 for btN8982TA. I decided to get them elsewhere

The “error” is correct so far. You have to choose the RS485 option, so none or standard-RS485 or THV8000. Have a look at page 1 of the schematic - there is an annotation to that.

Yes, prices/availabilty is a nightmare these days. Personally I would leave these parts unmounted, source from somewhere else and solder yourself. But that is not easy in some cases.

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@GoRoNb , Thanks for the all input & work you have put into this,
I am a farmer that has no real experience in Electronics, what I look for is autosteering not section control for now.

For the beginning, I planned to go with 1 ardusimple, then IMU. Maybe later on when things start to become more clear for me I can switch to 2 ardusimple setup.

For this reason and the beauty of your board, I planned to order the PCB. Watched your video here:

and when JLCPCB gave the placement error I mentioned in the previous message, I read the documentation over and over again until I feel confident.

So after feeling somehow confident I have chosen not to include RS485 and go for Power Line Communication, I also excluded items for Danfoss since I think I don’t need it.

is this the correct approach? In github you mentioned that:

Only mount R31, R32, if ESP shall forward serial data to the (piggyback) section control unit.

Only mount R49, R50, if ESP shall forward serial data to the steer unit (Atmel).

For 1 ardusimple assembling R31,R32,R49,R50 a problem?

After all, as a beginner would you recommend this board or PCB v2 . PCB v2 seems much simpler to me but requires soldering work.

if you plan to upgrade to dual, you should go for the V2. If you want to run Brian’s original code, you only need the Atmel µC and no ESP32. Even for dual, I wouldn’t use an ESP today as you can connect both Ardusimples via USB.

I know, I should publish different Bills Of Material (BOM) for different use cases… Work for the next time… :upside_down_face:

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I made a simplified BOM (“USB recommended”), which is likely the most common setup. It supports

  • Atmel µC (works out of the box with Brian’s code)
  • WAS (both single ended or differential)
  • power stage
  • USB hub to connect to one or two Ardusimple + one external device (e. g. IMU or GSM stick)
  • internal or external IMU option (BNO085 / CMPS14)

Unfortunately JLC is charging extreme unacceptable costs for some components , so the only chance these days is leaving those parts unmounted, source from somewhere else and mount yourself.

Furthermore, the ADS for the WAS and the USB hub IC are out-of-stock as well. So not easy these days…

In better days, this PCBA will be about $30 each + connectors, if you order 5 parts. We have to be patient…

Thank you, that will help most people like me. Just a question before placing the order,

  1. If I am gonna use electric steering not hydraulic do I need this “BTS50301EJAXUMA1”? Cant find a single stock on this component.

  2. I am getting repeated coordinate errors on the following parts. I uploaded both the screenshot I got from JLCPCB and xlsx file they provide. Although I am getting these errors, I can proceed to checkout and complete the order. Should I proceed and ignore those errors? I just downloaded the production data from the Github page.

4243334A20220325222543.xlsx (8.3 KB)

did you delete those parts of the option you don’t want?

alternatively I generated a BOM for the most common option. you may try this, but this doesn’t help for the stock shortage. it’s a nightmare…

Link to reduced BOM

I didn’t delete anything.
Here are the exact files I used to upload JLCPCB. I downloaded these from the above link.

Central unit 2.3.zip (697.7 KB)