Sightings

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

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

Why#

The Peak Atlas DCA75 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.