ASCOM Mount Dither

flux

The review package is updated. I’m also refreshing the project specification to match the corrected PhotoMOS/SPST revision.

flux

The project specification is refreshed to the corrected PhotoMOS version. I’m verifying the final file list and marking the revision complete.

flux

Final ERC/BOM/schematic checks are clean; no PCB placement/routing was started.

flux

Implemented the schematic-only V1 revision: replaced the TLP291-4 with four TLP171A(TP,F) PhotoMOS relays, replaced SW1 with a true SPST ON/OFF switch, preserved the V2 archive, and updated the review docs.
Updated files:
Open items:
  • No PCB placement/routing was started.
  • J1 pin-1 marker and “ST-4 - STRAIGHT 1:1 6P6C ONLY” silkscreen note remain layout-stage tasks.
  • Board outline, connector access, battery-holder position, and mounting method still need definition before placement.
Suggested next steps:
  1. Review/approve the corrected PhotoMOS schematic and BOM.
  2. Confirm SW1 = DS04-254-2-01BK-SMT is acceptable as the physical power switch.
  3. Confirm whether J2 should stay as a 1x03 UPDI header or change to test pads before layout.
Approve and prepare layout
Approve PhotoMOS schematic
Keep UPDI header
Define board outline
Verify RJ12 footprint
Review switch choice
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Files

Schematic

Layout

3D View

V2 USB Host Archive — Conditional Reference
Archive Point
The ESP32-S3 USB-host architecture was archived before the V1 redesign pivot to a minimal autonomous ST-4 dither timer.
  • Archived project commit: #5a204155 — immediately after creating the USB Host Compatibility Bring-Up Plan.
  • Archived schematic summary: 295 schematic elements, 41 nets, ESP32-S3 USB-host command-link architecture with LiPo charging, USB-C charge input, 3.3 V buck-boost, 5 V boost, current-limited USB-A VBUS, USB data ESD, debug header, and sync I/O.
Archived V2 Project Files
Status
This V2 architecture is preserved only as a conditional archive. It is not the V1 baseline.
Use V2 only if the minimal ST-4 approach is later rejected or if a future version needs mount-command USB control through the 8409 USB interface.
V1 Pivot Decision
The new V1 baseline is a minimal autonomous ST-4 dither timer:
  • No ESP32-S3.
  • No USB host.
  • No USB-A mount connection.
  • No LiPo charger or 5 V boost subsystem.
  • No display, Wi-Fi, Bluetooth, camera sync, or shutter output.
  • AAA-powered, low-power MCU, opto-isolated ST-4 RA+/RA-/DEC+/DEC- contact closures.

  • Archive Point

  • Archived V2 Project Files

  • Status

  • V1 Pivot Decision