Huvud, a 3D Printer Tool Head Controller Board

While it is not really possible/viable to produce any more Huvud v0.5 boards at the moment I am slowly working on an improved v0.6. Many component are very very hard to find, and if you manage to find any they are ridiculously expensive.

The main improvements on this new board are:

• On board accelerometer (ADXL345), 
• 3 endstops that are 5V tolerant 
• 5V supply

One more version was assembled today, and it works perfectly fine. The differences from before is an added ESD protection diode on the CAN bus and the CAN bus is now in the same connector as power. 

The CAN bus used to have it's own 4-pin JST PH connector but is now in the Molex Micro-Fit together with power. That connector is now a 2x2. 

This was the last prototype for this round and I will now start some volume production. First batch will be only 200 boards. It's hard to know how big the market is and as it's just a hobby project I take things one step at a time. 

Time to start hacking on the software some more now. The CAN-serial tunnel used by klipper is a bit hacky and needs some love. And a CAN bus capable bootloader would be awesome since it's a major pain to update the firmware if you have many boards.

And I should make a little jig for testing and programming the boards. Anyone have hints where to get pogo-pins or other useful test-jig items/software etc?

Pushing the poor little board to its limits. It smells funny and I managed to burn my fingers, but it keeps on trucking! 

The stepper driver protests at these temperatures and stops moving the stepper for short moments. 

The MCU reaches about 80C, which is a good thing, the heat transfer works as designed. I wish I had a FLIR to do some more detailed analysis.

It has now reached a good enough state and I am getting quotes for some minor volume production. Next step is to make a test-jig to be able to program and test the produced boards in an efficient manner.

New boards arrived!

The ripple on the 3.3V line is now at the expected 30mV with the TPS54308 controller. Very good! I'll test with a TPS54302 in a few days when they arrive. The '302 is $0.50 cheaper than '308 even if it has more fancy power saving features. 

Now for the horrible task of hand soldering the TMC stepper drivers. Not an easy task for an unskilled solderer like myself.

The board should be ready for volume production now. I just need to re verify that everything works as intended and push the boards to their limits.

The fourth version of the board is finally in the mail from assembly. 

The major change is that the DC-DC Switch Regulator Controller has been changed to a more modern and smaller version than before. I had issues that when the old one (TPS54331) went into low power "eco-mode" the output ripple sky rocketed to 100mV. The new controller (TPS54308) has no such features and should be more stable. I'll try the TPS54302 as well, same footprint, has the eco features and is a lot cheaper.

I have made some changes to the thermistor input subsystem as well. The construction for filtering was totally broken and had massive noise. 

Despite all these power/analogue issues all versions of the boards have worked perfectly fine. The klipper firmware has been tested and runs well on all kind of questionable 3D printer boards, far worse than this board.