Updated Motherboard Design Connection to RPi


I am building the eVOLVER from the available documentation (Nature paper, Fynchbio PCBs, vial board BOMs, tutorials here, etc.). I have a question on how the most recent Motherboard is supposed to connect to the RPi server.

The Nature paper and published BOM shows a DB9 connection from the RPi RS485 hat to the DB9 port on the (older design) motherboard, the newer design of the motherboard (Motherboard Rev E) we received doesn’t have a DB9 connection, but it does have a couple of USB ports not present on the earlier design. Is it safe to assume that the intended communication route is from the RPi RS485 hat to the USB on the motherboard? Will basically any DB9 to USB cable be suitable?

Additional note: I’m not adding the fluidics module, the only functionalities I am needing in my eVOLVER are temperature and agitation control and OD monitoring.


Hi Ben,

The older boards used a DB9 cable, we have since switched to a normal phone jack (RJ11). The USB port is used purely for power. We make our own Pi Hat with the RJ11 connector.

Hope this clarifies things.


Can someone tell me where I can find the most recent versions of all the PCBs?

My motherboard file still uses a DB9 connection and 7 pin connectors to the smart sleeves, but my most recent vial board file already has a 8 pin connector for closed loop control of the fan which I got from the evolver hardware git repository.
Where could I find this Rev E version of the motherboard and all the other boards most recent versions?

Thank you!

The repo should be updated now: GitHub - FYNCH-BIO/hardware: eVOLVER Hardware (PCB, 3D printed parts)

Please let me know if you have any questions.


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Hello, @bgwong!! Thanks so much for the reply.

I do actually have some questions, I hope you don’t mind. I haven’t worked much with eletronics before so here they go:

  • To connect the the PWM, ADC, RS485 and Arduinos onto the motherboard and auxiliary board, do I have to by two kinds of connectors (socket for the larger boards and male pin strip for the smaller ones) or could I simply buy one pin strip and solder the smaller boards directly to the larger ones?

  • In the auxiliary board, the J1 screw terminal is used for what? And the J3 jack terminal is listed as DNP in the BOM file, but it is essential to connect it later, for it is the power source, correct? And in respects to the J2 and J4 terminals, are they essential for the board? What are they used for?

  • Still in the auxiliary board, when quoting the PCBs, the vendor suggested SMD capacitors instead of the through hole ones suggested at the BOM file (from Digi-key). Could I accept the change? In general, how flexible is it to change components with similiar ones that don’t have the exact same specifications?

  • In the vial board, what are the spare A and B terminals for? Are they there only so that if we’d like to add other sensors/actuators in the future it would be possible? And in respects the the 82 ohm resistors, is it necessary to have all 4? And would it be possible to change to a different resistance?

  • Still in the vial board, why was the terminal where the fan is connected changed to 4 positions? Is the fan changed to a 4 wire or 3 wire one? what is connected to these positions?

  • In the motherboard BOM file, many things confused me. First, can the the capacitors be changed such as in the auxiliary board? I believe they have the same specifications. Second, in the BOM file, we have J1 to J8 connectors but in the KiCAD drawing, I could only find the J1, J2 and J4 connectors, which seem to be used for what the BOM file suggests J2, J3, J5 and J6 are going to be used for, as USB connectors (and the J4 connector I don’t actually understand what it is for) . Could you explain if there is an error or for what the J1 to J6 connectors are used for? I could only understand the use for J7 and J8, which is for the RS485 communication. I also couldn’t find the JP 1 to 8 jumpers in the drawing or figure out what they are used for. The same for the P1 to P9 connectors.

  • Still in the motherboard, what is the P31 connector used for? And the P38 to P50? In the drawing we have P31 and P38 to P60 connectors but in the BOM file only P38 to P50, is that right? or is it just a matter of naming the connectors differently. Also, what are all these P connectors used for? And what is via stitching (the TP component on the BOM file)? It isn’t a component I can buy, correct?

  • The RS485 board files weren’t at the git repository so I’m assuming the version in the fynchbio documentation page is the most recent one, is that correct?

  • Also, I see you’ve added the Pi-hat board! In it, I was wondering what the J2 to J5 and the J7 connectors are for.

  • Lastly, I’ve also seen that there are some other boards in the accessories file. What are they used for? Is temp-cal necessary for temperature calibration? Is the flow-rate-aux-board necessary to measure flow rate? Also, the pump_board is only used organize the pumps and aren’t necessary for the to work, correct? And whyy is the resistor-pack necessary and where does it go?

I understand there are many topics but I would really appreciate it if you could help me better understand how the evolver works as a whole. Thank you!

You can solder directly onto the motherboard, but I would recommend investing in the extra sockets, for the modularity. If for whatever reason the PWM or ADC boards malfunction, swapping out the board that is soldered directly is more of a pain.

The pins are labeled on the PCB. J4 is for a fan to increase airflow through the chassis or box. J2 is input to 5V logic (can be powered via the Arduino also). J1 is the 12V input. J3 is an alternative 12V input from a 5.5mm barrel connector.

You are free to change whatever components you want (at your own risk). That said, most components are pretty simple and interchangeable. To change to SMD, you will have to change the CAD.

The resistors are current limiting resistors for additional LEDs. You can modify the board for whatever purpose you need.

We had plans to integrate a fan with tachometer control, but never got around to do it yet. We normally use a 2 wire, 12V brushless DC fan.

The BOM is out of date and its been honestly pretty hard to find parts due to a lot of manufacturing issues worldwide. I probably do not have time to update the BOM at this point in time. Most of the USB connectors are to provide power to other components (e.g. touch screen) and are not important.

The only critical connectors is RS485 connector (to the Raspberry Pi), 12V power input, and 5V power input.


The only connector that needs to be populated is J6 (You need a RJ11 cable that goes from the Pi Hat to the Motherboard). You also need a cable that goes from the Motherboard to Fluidics Box. The cable from the Pi Hat to the Motherboard needs to be reversed orientation (connectors should have opposite pinouts). The cable from the MB to fluidics box is the straight orientation.

This is more for projects we are developing. Please ignore them.