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Board inventory & Detect fixture report

An inventory of the boards on hand, compiled from the Firmware Detect fixture campaign (2026-07-18).

Data was gathered with esptool (authoritative for Espressif — chip, flash, security), mpremote / CircuitPython REPL (runtime freq, heap, build), and UF2 INFO_UF2.TXT / boot_out.txt for bootloader-only boards.

Note on flash/RAM columns: for ESP32 boards flash size and PSRAM are measured by esptool. For non-ESP boards, flash and SRAM are authoritative chip / board specs (RP2040 / SAMD / nRF52 / STM32 / i.MX RT datasheets and known board hardware); the free heap (~… free) is what the runtime reported at probe time. External QSPI flash is called out as +N MB QSPI (MCUs like RP2040 and i.MX RT have no internal program flash).

Summary

• 30 data points captured across ~24 distinct physical boards (several generic ESP32-S3 modules and ESP32-PICO-V3-02 units were re-probed; see Duplicates).
• 6 firmware ports represented: esp32, rp2, samd, nrf, mimxrt, stm32.
• 3 runtimes seen in the wild: MicroPython, CircuitPython, Arduino/bare.

By firmware port

By chip family

Superlatives

• Fastest: Teensy 4.1 (i.MX RT1062) 600 MHz; Metro M7 500 MHz; ESP32-P4 400 MHz.
• Most flash: ESP32-P4 32 MB (all other ESP boards are 8 MB).
• Most RAM/heap: ESP32-P4 ~33 MB and the SPIRAM S3s ~8.3 MB free.
• Only Arduino/bare board: fixture 6 (ESP32-S3, no MicroPython — proves esptool-first Detect works with no REPL).
• Trickiest to flash: Feather nRF52840 Express (SoftDevice S140 6.1.1 pinning) and the PyRuler clone (UF2 not sticking — left for later).

Inventory

Most interesting datum per board

ESP32

• #1 ESP32-P4 — the outlier: 32 MB flash, 400 MHz dual-core + LP, ~33 MB heap, and an external C6 Wi-Fi co-processor that esptool can't see (variant only knowable from MicroPython _build).
• #2 ESP32-S3 — clean "no PSRAM" baseline: ~214 KB heap despite the generic S3 module string.
• #3 ESP32-S3 Octal — machine string literally says Octal-SPIRAM → unambiguous SPIRAM_OCT; ~8.3 MB heap.
• #4 ESP32-S3 — the cautionary case: generic machine string with no "SPIRAM", yet ~8.3 MB heap proves external RAM → variant must come from heap, not the string.
• #6 ESP32-S3 (Arduino) — no MicroPython at all; esptool alone reports Embedded PSRAM 8MB. Proof that Detect works on a bare board.
• #8 Qualia S3 RGB666 — CircuitPython reports sys.platform == 'Espressif' (not esp32); family must be inferred from implementation.name.
• #9 / #10 ESP32-S3 (CH343) — external USB-UART bridges let esptool succeed first-try; identity keyed on MAC, not the (shared) adapter serial.
• #12 / #14 / #15 / #22 ESP32-S3 batch — four physically distinct modules (distinct unique_ids) that all report the same generic string + bogus USB serial 123456 → never key identity on USB serial.
• #13 FunHouse (ESP32-S2) — the only S2; uname ESP32S2 + ~2 MB heap → S2 + SPIRAM.
• #17 / #20 / #28 ESP32-PICO-V3-02 — the classic-ESP32 case: embedded flash and PSRAM in one package; get_security_info is not implemented (must be tolerated, not treated as a failure).

RP2040 (rp2)

• #7 Feather RP2040 — Adafruit VID 0x239A also ships ESP32-S3, so VID alone can't gate "skip esptool".
• #11 Waveshare RP2040-Plus — true Raspberry Pi VID 0x2E8A; only 4 MB flash.
• #16 Raspberry Pi Pico — reference RP2040, 2 MB flash.
• #21 Feather RP2040 DVI — running overclocked at 252 MHz; no dedicated DVI board in the MP tree (closest ADAFRUIT_FEATHER_RP2040).

SAMD (samd)

• #18 QT Py M0 — caught in UF2 bootloader (QTPY_BOOT); Board-ID from INFO_UF2.TXT is the detect key.
• #24 Thing Plus SAMD51 — exact MP board match SPARKFUN_SAMD51_THING_PLUS (samd51j20).
• #26 PyRuler — SAMD21 clone with no MP board; UF2 wouldn't stick (returns to TRINKETBOOT) — a known recovery gap left for later.
• #27 PyGamer — samd51j19 (contrast the j20 Thing Plus); closest SAMD_GENERIC_D51X19.
• #30 Trinket M0 — the genuine article; exact MP match ADAFRUIT_TRINKET_M0.

nRF52840 (nrf)

• #19 XIAO nRF52840 Sense — Seeed VID 0x2886; CIRCUITPY-only, UF2 flash path.
• #29 Feather nRF52840 Express — bootloader pins SoftDevice S140 6.1.1; a default 7.3.0 UF2 fails — must match the SoftDevice version when building.

NXP i.MX RT (mimxrt)

• #5 Metro M7 — entry i.MX RT1011 at 500 MHz; 128 KB SRAM (~60 KB free at probe), program runs from 8 MB external QSPI.
• #23 Teensy 4.1 — the speed king at 600 MHz, ~927 KB heap; flashed via HalfKay HID (teensy_loader_cli), not esptool.

STM32 (stm32)

• #25 NUCLEO-H743ZI2 — reports a frequency tuple (400, 200, 100, 100); flashed by ST-Link mass-storage drag-and-drop.

Duplicates / repeat probes

Some models were probed more than once (distinct silicon, verified by unique_id/MAC), useful for hardening the matcher rather than counting as separate models:

• Generic ESP32-S3 (no PSRAM) ×4 — fixtures 12, 14, 15, 22 (COM10 cohort).
• ESP32-PICO-V3-02 ×3 — fixtures 17, 20, 28.
• ESP32-S3 + Embedded PSRAM via CH343 ×2 — fixtures 9, 10.

Counting each model once gives roughly 24 distinct boards on hand.