EPG Rig Redesign

An open, modern redesign of the Electrical Penetration Graph (EPG) recording rig — new hardware, firmware, and software — to replace the commercial Giga-8dd (EPG Systems EU / W.F. Tjallingii). Used to record stylet-penetration / feeding behavior of the pea aphid Acyrthosiphon pisum.

Goals

1. Improve temporal resolution of sampling (original: 14-bit ADC @ 100 Hz default).
2. Reduce production cost.
3. Simplify construction.
4. Automate voltage-drift correction — the electrode-potential drift currently corrected by hand via the supplied voltage (Vs). An auto-detect/correct in firmware/software.
5. Cross-platform software — original Stylet+ is Windows-only and needs custom USB/COM/ActiveX drivers.

Status

Early design phase — working through architecture decisions interactively. See docs/design-log.md for locked decisions and rationale.

Document index

• docs/design-log.md — decision log (what's locked + why).
• docs/system-architecture.md — consolidated block diagram
  • signal chain as decided so far.
• docs/noise-bandwidth-budget.md — quantitative noise & bandwidth analysis → gain, ADC, and the layout-critical input-capacitance spec.
• docs/protocol-and-data-format.md — USB device↔host protocol + HDF5 recording format (draft v0.1).
• docs/original-circuit-reference.md — facts extracted from the Giga-8dd manuals (the circuit we're modernizing).
• docs/conversation-log.md — chronological narrative of the design discussions.

Folders

• docs/ — design docs and decision records.
• hardware/ — single-channel-schematic.md (draft v0.1, SPICE-verified), pcb-layout.md (layout spec / hand-off); hardware/sim/ ngspice netlist; hardware/netlist/ (ERC-checked netlist + generated single_channel.kicad_sch with footprints + SVG/PDF); hardware/pcb/ (pre-placed single_channel.kicad_pcb, custom .kicad_dru, board render).
• firmware/ — RP2040 firmware: portable C protocol (host-tested + interop-verified vs the Python codec) + Arduino app skeleton.
• firmware/ — MCU firmware (to come).
• software/ — cross-platform acquisition + analysis app, Python/pyqtgraph (to come).

Source material

Original vendor documentation lives one level up in ../Giga_rig_manuals/ (start with Measuring principles.pdf; differential probe circuit is Appendix 5 / Fig 13B of Manual-Giga-8dd 20.pdf). The original Windows software in ../original_rig_software/ is distributed only as .exe installers, so the Stylet+ data file format is not recoverable from it — we will define our own open format.