CircuitMaker Pixhawk2 boards

Hardware Pixhawk 2
1

I’ve redrafted the schematics for each of the Pixhawk2 boards using the most recent versions released by 3DR. Many of the existing schematics appear to have been at some time imported from Eagle, without much cleanup. These designs do not include the revisions made for Pixhawk2.1 which are not publicly released (what is released is incomplete, obfuscated and placed under a different licence). Each new schematic correctly syncs with the associated PCB layout, but I haven’t made significant changes to the layouts, other than to revise pin numbering / naming to be consistent with new schematic symbols. A couple of obsolete parts have been replaced with drop-in replacements (Kyocera filter, and FRAM) but the BOM is otherwise unchanged. There are a number of capacitors that should be replaced with better versions (Y5V).

The sensors used are mostly obsolete now. Aside from the stand-alone magnetometer (Honeywell), there are replacement parts available from the respective manufacturers (ST, Invensense), but I am not certain if these are directly supported by the firmware. The Edison compute module is also now EOL, but the board will serve as a good starting point for new designs.

This work was performed in Altium Designer, but I have imported each design into the free to use CircuitMaker tool, with links to each project below,
https://circuitmaker.com/Projects/Details/James-Brown-20/PCB00001AFMU
https://circuitmaker.com/Projects/Details/James-Brown-20/PCB00002AIMU
https://circuitmaker.com/Projects/Details/James-Brown-20/PCB00003A-PSM
https://circuitmaker.com/Projects/Details/James-Brown-20/PCB00004ACBEDISON

From this point I would like to make some structural changes to the designs, including the following,

  • Update sensors to current parts, including the MPU9250 (replaces MPU6000 and HMC5983), L3GD20HTR, LSM303DLHCTR.
  • (re)Implement IMU heater.
  • Remove line-drivers, CAN transceivers, LEDs, USB components from the FMU; these should be incorporated on the carrier, where/if required.
  • Revise FMU to eliminate blind vias, reduce to 6 layers.
  • Change the DF17 to a generally available version (the current designs use a part which is difficult to obtain).
  • Revise IMU to use FFC cable, rather than the rigid-flex design.
  • Implement a new carrier board, to support Raspberry Pi 3 compute module (or other). May or may not use PSM.
  • Generally improve PCB layout quality.

I have no time-frame on the above, but I thought I would share the designs. I have seen discussion about attempting to port the design to a free tool, and CircuitMaker seems the natural fit.

2

Added PDFs to each project, so people can view the schematic without installing CircuitMaker.

3

Well done. it’s a shame about the non-free, windows-only tool that’s used for Pixhawk2 - hope what you did will start something good :slight_smile:

4

To be fair, I don’t believe there are any open-source tools that are adequate for creating designs of this complexity. I use Altium for my job, so I am most comfortable using it. CircuitMaker is a free-to-use cut-down version provided by Altium, and directly supports the schematics (SchDoc) from Altium, but uses an older version of the PCB file format, requiring current AD boards to be saved as PCB v5/6, and then imported (transferring the CMPcbDoc also requires importing into AD, and can’t be directly opened, but it is supported).

I am now looking at doing the same for the PixRacer, with a mind to create a FMU_LITE board, that shares the same IMU and form factor as the regular FMU. There’s quite a bit of stuff in the FMU that isn’t used by the majority of users (e.g. F1 backup processor adds little for a multirotor which cannot make use of direct pass-through in the event of main processor failure). The limitation of 6 motor channels also won’t affect most users.

The main issue I have to resolve is whether the sensors can be changed, and maintain compatibility with the existing PX4-V2/V3 (as far as I can tell the only difference here is that V2 limits flash usage to 1M, due to the < Rev3 F427 flash bug) and PX4-V4 targets. If at all possible I’d like to avoid and changes that affect firmware (require changes / support).

5

yes, at this level, openness is secondary, but the tools should be available on Linux, I am not going back to the 90’s and windows :slight_smile:
I was pretty happy with Eagle.