Huvud 3D Printer toolhead board

A very small 3D printer board for use on a toolhead. It is designed to be used with Klipper firmware.

Features:

• TMC2209 stepper driver
• STM32F103 72Mhz MCU
• Two MOSFET drivers fans
• One bigger MOSFET driver for a hotend heater
• Thermistor input
• One endstop
• CAN bus
• USB

Main power is 12-24V. 24V is preferred to keep the currents low

All done in KiCad and open source.

Change ideas:

• Find a better heater mosfet, our 3.3V Vgs is on the low side for that chip.

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2020-05-18:

First prototype production run is done.

They work!

2020-05-29:

After a lot of software work and many hours of testing I can report that everything actually works as intended (except one resistor that was a 10k insteadof 1k)

• The thermistor input gives a very low noise signal, even at high temperatures.
• Endstop works
• All mosfet outputs works with reasonable loads (2A at 24V). I do not have a dummy load for high load testing, but a heater on the FAN connectors and a hotbed to the heater connector...
• The thermals of the TMC2209 seems ok. With no cooling fins or active cooling it reaches 60C (top and bottom) when mounted close to a hot stepper. I should test with a larger stepper (>1.5A) in a hotter environment to see when the TMC shuts down. I am considering a different fab that allows thicker copper layers for better heat spead, and better power margins.
• The CAN bus works good after some software work. It should work fine with up to 8 nodes on each bus, possibly more. I have run 4 boards on the same bus, each with one stepper, simulating a complete 3D printer.

It is possible to fit different connectors for most functions. It is designed for mostly angled JST-XH or screw terminals but it's possible to fit straight connectors or other 2.54mm for most functions. JLCPCB do not mount through holes so the boards come without connectors. For a larger (>30) production run the boards would have to be panellized, which looks like a non-trivial task with KiCAD. If anyone has experience and wants to help ...

2020-06-04:

Version 0.4 in the works...

Can Hat

As a sub project to this board I have developed a little power and CAN distribution board combined with an MCP2515 CAN bus controller in the form of a Raspberry Pi Hat. It is a very simple little board but has turned out to be very valuable.

With some more thought put into it I think it will be a good complement to the Huvud tool board.