# SightingsA DCA75 workbench for macOS, Linux, and Android.

**Source:** [github.com/drlholloway/sightings](https://github.com/drlholloway/sightings) (Flutter and Dart, PolyForm Shield)

**Platforms:** macOS, Linux, Android (USB host / OTG).

## Why

The [Peak Atlas DCA75](https://www.peakelec.co.uk/acatalog/dca75-dca-pro-semiconductor-analyser.html)
is a wonderful little semiconductor analyser, but the official companion
software is Windows only. I wanted to use it from the Mac on my bench, from a
Linux box, and from a phone with an OTG cable, and I wanted every reading kept
somewhere I could search later.

## What it does

- **Identify.** Press *Test* in the app or the button on the unit. Readings
  are decoded and saved immediately, or held as a draft you can tag with a
  part number and bin before saving.
- **Curves.** Ic/Vce families, hFE vs Ic, Id/Vds, Id/Vgs, and PN I-V sweeps
  with live plotting, cancel, CSV and PNG export, and overlays of saved sweeps.
- **History.** Filter, tag in bulk, export CSV, delete.
- **Parts.** Per-part and per-bin statistics, histograms, and closest-match
  search for transistor matching.

## How it is built

The code is split into small packages: a pure Dart protocol layer for frames, opcodes, and decoders; a
transport layer over libusb via `dart:ffi` with fake and replay transports
for testing; a typed device client with a connection controller and sweep
engine; and a SQLite store built on drift. A small CLI can decode, probe,
identify, and bench from the terminal without the app.

## Safety

The app never writes to the unit's firmware, calibration, or serial number.
Those opcodes cannot be constructed in the protocol library, and the EEPROM
write-arm status byte is rejected at the transport. Every error path returns
the unit to its leads-safe state.