OpenBCI Hardware KiCAD

CoubyCouby France
edited April 2017 in Cyton
Hi OpenBCI community,

I open this topic to share about my work in progress redrawing OpenBCI hardware with KiCAD.


This work is really at its beginning, so feel free to correct or comment... or to share if you already have done the work :-).
For the moment I just redraw the ADS1299 block.

Hope that could help some other people interested working with KiCAD.

Thanks again to OpenBCI team for this fantastic project.

Regards

Comments

  • CoubyCouby France
    Hi,
    Today draw update with power supply part.
    I also added a functional scheme about this electronic. Even if obvious I think that can help for learning/understanding curve for new comers. If I made mistakes, corrections are welcome :o).
    Regards.


  • biomurphbiomurph Brooklyn, NY
    @Chouby,

    Super cool that you are working on KiCad! I should be able to assist with your design as it grows.
    I made an alteration to the power supply circuitry recently. In our latest shipments, I changed the digital 3V3 reg to one that can take a higher voltage on it's input (up to 12VDC). I also changed the spec on the decoupling cap on the input as well.

    That change also impacts the BLE|PC switch functionality. The BLE|PC switch potentially 'tells' the RFduino if it should be running the GZLL stack or the BLE stack (this is not currently implemented in software!!). Because of the possibility of a higher voltage input, I've had to change that circuit from a V divider to a 3V Zener to input a safe signal into the RFduino....


  • CoubyCouby France
    Thank you @biomurph for these encouraging words :-).

    I'm a bit off these days, being not too far in Orlando (always closer than from the other side of Atlantic :-) ) for iitsec.

    Will be back at work on kicad next week. Redrawing scheme is easy, when coming to component footprint and PCB, will be another story.

    Thanks for the news on scheme updates. Will do my best to be at the edge with it !

    Really looking forward beeing back on it :-).

    Regards
  • CoubyCouby France
    Today update.

    Scheme :
    + ADS decoupling
    + SD CARD
    + Accelerometer

    Library :

    I'm using Amphenol 101-00303-68-1-ND for SD CARD reader, and ADXL345 for accelerometer. These scheme adaptations should be checked as I never used such components till there. If someone see better adaptations, orientations are welcome :-).
  • CoubyCouby France
    Day update.

    Scheme :
    + Input filtering

    Library :
    + rn-cay16-f4
    + tpd4e1b06
    + CKCL44X7R1H102M085AA

    Need to refine and sort library components...
  • CoubyCouby France
    Day update.

    Scheme :
    + Microcontroller
    + RFDuino

    Library :
    +pic32mx250
    +RFD22301

    Scheme is complete. There are possibly mistakes so any check is warmly welcome.
    Now I'm exploring the steps to go from scheme to pcb design...
  • CoubyCouby France
    Just some details...

    Using the electronic rules checker, I noticed on ADS1299 that pin 64 is grounded while in the ref documentation it is precised to not connect it. In the user manual it is also grounded so I changed the rule on this pin in order to ground it. This comment doesn't bring anything but if someone notice this detail and wonder why it is grounded, this seems to be the way it works :-).

    On the RFDUINO Module scheme, pin 14, 16 and 17 are not wired to anything (RF_RESET, RF_TX0 and RF_TX0) so I unwired them. Did I miss something ? :-/

    @biomurph how will you proceed to share your power supply changes ? I don't see new branch on your GitHub repos. I think a simple way to proceed could be to publish work in progress on a WIP branch. I could then try to stay on track with a WIP branch on the KiCAD repos. That's just a proposal :-).


  • biomurphbiomurph Brooklyn, NY
    pins 14, 16, and 17 are the RESET, RX, TX pins for the RFduino. They are wired to a series of pads on the back of the board that are used for flashing the radio firmware, and grouped with 3V and GND pins.

    The changes to the power supply are only in the BOM. I found a part that has the same pinout. I will update the BOM shortly. Getting back up to speed here...
  • CoubyCouby France
    Thanks for these details about pins 14,16 and 17 for RFduino :). I'll pay attention for these traces when working on the PCB, and I'll think how to document it with the sources.

    Great news for this BOM update :).

    I'll soon be back on the work on component libraries for the PCB step.
  • marshmallowmarshmallow

    I am modifying the designs on DesignSpark. I have a slight confusion. I though i should ask you too since you have made the designs from scratch. 

    The resistor R5 (1M ohms, connected to pins 62, 63 of ADS1299) when translated to pcb gives a relatively larger footprint of 0402 (with rectangular pads) as compared to the capacitor (e.g. C16 connected in parallel with it) footprint of 0402 (with square pads). I noticed that they have been configured that way in the OpenBCI parts library. But in the 32-bit board design, both capacitor and resistor footprints of 0402 are the exact same (with square pads). What should I implement then? 

    Kindly reply as soon as you see this

    Thanks
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