project-alpaca / lkp Goto Github PK

• Slightly increase vertical board size (do we still need this?)
• Move all non-sensor connectors to the back side
• Better labeling

Yet another cheap+JLCPCBAble attempt. Uses RP2040+CY8CMBR3116-LQXI. Will likely have a different firmware than LKP-Core due to significant architecture change.

• Initial feasibility study
  • Datasheet, register map and design guide (has more info on purpose of registers and design patterns) for CY8CMBR3116-LQXI
  • In the dev board manual: "Cannot be used because GPO7 is multiplexed with
    the host interrupt so brought out to a header." Is interrupt not usable? (Looks like it should be usable if we just set it to ~HI right after boot.)
  • No active shielding will be available since it's muxed with one of the 16 sensor pins, which we need all of them to be used as sensors. Might be an OK tradeoff since the official controller doesn't have shielding either. In this case, the shield pins on the tile should probably be connected to the ground or floating.
    • Measure it on LKP-Core by disabling and {,not} shorting SH to ground (or put them in open drain low/high mode).
      • Result: Driving to ground increases Imod considerably (~22 -> ~33) due to higher parasitic capacitance although still within spec and SNR stays roughly in line with default, but floating causes the SNR to drop significantly (~80-90 to ~33 on naked PCB). Go with grounding SH seems to be the better choice.
    • This can probably also be compensated somewhat by parallel scanning and sensitivity increase, as long as parasitic capacitance is under control.
• Schematics
• Firmware PoC
• Initial PnR
  • 4 layer stack (in general): touch, 3v3+keepout, gnd+hatch, rp2040. may put touch @ bottom. put some passives (namely cmod but potentially other caps as well) at opposite plus using blind vias to increase density
  • PH power at the bottom, USB at the top
• PCB Prototype
• Firmware PoC test

These still use the old eeschema format. Move them to the new format.

Now KiCad 6 is out, it makes sense to upgrade.

So they can be loaded directly by KiCad nightly without the need to convert them every time.

Pop'n Music Welcom to Wonderland slider controller.

Currently known info and ideas:

• 45x8 addressable RGB LED matrix as backlight
  • Maybe possible to implement as a hollowed out sensor board and a dedicated WS281x board/strip array
• Probably needs to put LKP in CSX mode to achieve the resolution
• More info to come

Now we got the detailed chunithm slider dimensions and the long-overdue LKP-Chu finally can be continued.

Slider dimension with pics: https://gist.github.com/2f6263656d174fb2284a9e49c44bfabc