seismo-relay/docs/micromate_protocol_reference.md

# Micromate Protocol Reference — Thor / Micromate Series IV, live wire protocol

Sibling to [instantel_protocol_reference.md](instantel_protocol_reference.md)
(Series III, "the Rosetta Stone") and
[idf_protocol_reference.md](idf_protocol_reference.md) (Series IV *file*
format).  This document covers the Series IV **live device protocol** — what
the unit says over the wire, as opposed to what it writes into a `.IDFW`.

**Status (2026-09-23): opening session.** Everything below was established in
a single bench session against one unit.  Treat it as a strong start, not a
settled spec — in particular, everything here comes from **one unit, over USB,
with no events stored**.

---

## The headline

**A Micromate running the *Blastware* firmware answers Series III command
frames.**

An unmodified Series III `POLL` (`SUB 0x5B`), built by
`minimateplus.framing.build_bw_frame` with no changes at all, produced a
complete two-step probe/data cycle.  Ten Series III read commands were then
tried and **all ten answered**, every one obeying the Series III response-SUB
rule.

⚠ **That qualifier is load-bearing, and it was discovered after the fact.**
Instantel ships the Micromate in two firmware lines:

| firmware | Instantel's own description |
|---|---|
| `11.0CB` | "Utilize with **Blastware**" |
| `11.0BD` | "Utilize with **THOR, Vision, Vision II**" |

The bench unit reports **`11.0CB`** — the Blastware build.  So the clean
Series III behaviour above is very likely *because the unit is in Blastware
mode*, not because the Micromate natively speaks Series III.  **Nothing here
should be assumed to hold on a `11.0BD` unit until tested.**

This reframes the project.  The question is no longer only "what is the
Series IV protocol" but **"which firmware line do we target, and does one of
them let the existing Series III stack drive the whole fleet?"**

---

## Firmware — the variable nobody knew was a variable

This explains a production problem TMI has lived with: two ACH servers, two
machines, and units that will not cross over.  It is not a misconfiguration.
**Instantel ships different firmware for different host software**, and the
wire protocol differs with it.

### Fleet audit (physical, 2026-09-22/23)

| unit | firmware | line | location |
|---|---|---|---|
| UM11719 | `11.0CB` | Blastware | Ped Bridge Loc 2 |
| UM6047 | `11.0CB` | Blastware | Brookville Loc 9 |
| UM12947 | `11.0CB` | Blastware | **bench** |
| UM14133 | `11.0CB` | Blastware | Pitt-Music Bldg Loc 1 |
| UM11402 | `11.0BD` | Thor | Ped Bridge Loc 1 |
| UM20147 | `11.0BD` | Thor | **bench** |
| UM13981 | `11.0AK` | pre-split | RKM Loc 1 |
| UM20146 | `11.0AK` | pre-split | Karns Loc 2 |
| UM12420 | `10.90GC` | pre-split | RKM Loc 2 |

**4 Blastware / 2 Thor / 3 pre-split.**  The Blastware line is already the
plurality, which makes "standardise on Blastware" less disruptive than it
first appeared.

A store-derived audit (firmware is recorded in every `.sfm.json` sidecar as
`extensions.idf_report.version`) agreed with the physical audit on **7 of 9**.
The two that differed — UM6047 and UM14133 — are the most recently deployed
units, reflashed after their last stored event.  Useful technique: the fleet's
firmware history is reconstructable from the store without touching a unit,
but it lags reality by one deployment.

Firmware is **not stable per-unit over time** — five of nine have been
reflashed at least once.  Any fleet-wide claim needs a fresh audit.

### ⚠ Retraction: firmware line does NOT determine Thor compatibility

An earlier draft of this document suggested that UM12947's trouble with Thor
was explained by its being on the Blastware build.  **That is not supported.**

Ped Bridge runs UM11402 (`11.0BD`) and UM11719 (`11.0CB`) side by side, both
deployed 2026-04-20, and **both call Thor successfully** — UM11719 has 331
Thor-collected events in the store while on `11.0CB`, through 2026-08-23.

So a Blastware-line unit does feed Thor.  Whatever the CB/BD split changes, it
is not "which host software can collect from it", and UM12947's specific
problem remains unexplained.

**What is actually established:** a `11.0CB` unit answers Series III command
frames.  Whether a `11.0BD` unit does is **untested** — and UM20147 (`11.0BD`)
is on the bench, which makes that a direct A/B away.

The version is readable over the wire from `SUB 0x01` as two separate ASCII
runs — `"0CB"` then `"11"` — with no single concatenated string.

### The strategic fork

- **Option A — standardise the fleet on the Blastware line.**  Every unit,
  MiniMate and Micromate alike, then speaks Series III, and the existing
  `minimateplus/` stack drives all of it.  One protocol, one call-home
  receiver.  Dramatically cheaper *if* it holds up.
- **Option B — reverse-engineer the Thor line (`11.0BD`) and support both.**

Option A is the shortcut, but it is unproven and carries real unknowns, all
of which are cheap to answer on the bench and expensive to discover later:

1. **What file format does a `11.0CB` unit produce?**  If it emits Blastware
   binaries rather than `.IDFW`/`.IDFH`, the (now exact) Series III decoder
   applies and the IDF codec becomes a legacy path.  Not a loss — we have
   both — but it changes what the ingest pipeline sees.
2. **Does Thor still work with a `11.0CB` unit?**  If not, flashing a
   production unit breaks data collection until the replacement path exists.
3. **Are any Micromate-specific capabilities lost** on the Blastware line?
4. **Is the flash reversible in the field**, and what does it cost in downtime?

## How this was obtained

No Thor, no modem, no Windows machine.  The Micromate exposes its protocol on
a **USB CDC-ACM virtual serial port**:

```
ID 2504:0300 Instantel Inc. MICROMATE COM PORT
driver: cdc_acm          ATTRS{serial}=="V1.00"
→ /dev/ttyACM0
```

Plain CDC ACM, so no vendor driver and no proprietary USB layer — any host
that can open a serial port can talk to the unit.

**Baud is irrelevant over USB.**  Identical byte-for-byte responses at 38400
and 115200; CDC-ACM ignores the line rate.  TMI provisions Micromate *modem*
links at **115200** (Series III uses 38400) — that matters for the cellular
path, not for USB.

**The device never speaks first.**  20 s of passive listening on an idle open
port produced zero bytes.  It is strictly request/response.

---

## Physical + framing layer

### Requests — Series III format, unmodified

Every frame in this session was produced by `build_bw_frame(sub, offset)` with
no Series IV changes, and the device accepted all of them:

```
[ACK 0x41] [STX 0x02] [10 10] [flags 00] [SUB] [00] [00] [offset] [params×10] [chk] [ETX 0x03]
```

⚠ Only the doubled `BW_CMD` (`10 10`) form has been exercised.  Whether other
literal `0x10` bytes inside params require stuffing is **untested** — none of
the probes sent carried one.

### Responses — Series III *minus the DLE prefix*

```
Series III:   [DLE 0x10] [STX 0x02] … [chk] [ETX 0x03]
Micromate:              [STX 0x02] … [chk] [ETX 0x03]      ← no leading DLE
```

This single byte matters operationally: Blastware's parser locates frames by
scanning for `DLE+STX`, so it will **never find a frame boundary** in Micromate
traffic no matter what else is correct.  That is a structural reason a
Micromate cannot call into a Blastware ACH server, independent of any baud
mismatch.

### Response payload header

```
[0] CMD    0x00          same as Series III
[1] flags  0xC5          ← Series III uses 0x10.  Constant across all 10 SUBs.
[2] SUB    0xFF − request_SUB
[3] PAGE_HI
[4] PAGE_LO
[5+] data
```

### Checksum — the DLE-aware variant

```python
chk = sum(b for b in payload if b != 0x10) & 0xFF
```

Confirmed on every frame captured.  The `POLL` probe response contains no
`0x10` and so cannot distinguish plain SUM8 from the DLE-aware form; the
`POLL` **data** response contains a `0x10` at payload offset 42, and only the
DLE-aware rule matches there.  This is the same checksum Series III uses for
its `5A` bulk-stream and write frames — not the plain SUM8 of ordinary
Series III reads.

### The probe response carries the data length

Series III hardcodes `DATA_LENGTHS` per SUB.  On the Micromate the **probe
response tells you**, as a **uint16 BE at `payload[8:10]`**:

⚠ **Corrected 2026-09-23.**  An earlier draft read this as a single byte at
`payload[9]`.  That is right only while the high byte is zero, and it is
catastrophically wrong for `SUB 0x1A`, whose real length is `0x082C` = **2092**
— read as a byte it gives **44**, a 47× under-read.  Always read the pair.

| SUB | command | `payload[9]` | Series III constant |
|---|---|---|---|
| `0x15` | serial number | `0x0A` | `0x0A` ✓ |
| `0x01` | device info | `0x98` | `0x98` ✓ |
| `0x1C` | monitor status | `0x2C` | `0x2C` ✓ |
| `0x06` | storage range | `0x24` | `0x24` ✓ |
| `0x2C` | call-home config | `0x7E` | `0x7C` ✗ **differs by 2** |
| `0x08` | event index | `0x5A` | — |
| `0x1E` | event header | `0x08` | — |
| `0x1A` | compliance config | `0x082C` (2092) | — |
| `0x0A` | waveform header | `0x00` | — (no event context) |
| `0xFE` | full config | `0x00` | — (see note) |

Four of four known Series III lengths match exactly.  **Read the length from
the probe rather than hardcoding it** — it is free, and it already caught the
call-home divergence.

---

## Confirmed commands (read-only)

All ten below answered with a correct `0xFF − SUB` response.  Nothing that
writes, erases, or changes monitoring state has been sent to a unit.

| SUB | RSP | Command | Data proven |
|---|---|---|---|
| `0x5B` | `0xA4` | POLL / handshake | yes — ID block |
| `0x15` | `0xEA` | Serial number | yes — `UM12947` |
| `0x01` | `0xFE` | Device info | yes — 152 B |
| `0x2C` | `0xD3` | Call-home config | yes — 126 B |
| `0x1C` | `0xE3` | Monitor status | yes — 44 B |
| `0x06` | `0xF9` | Event storage range | yes — 36 B |
| `0x08` | `0xF7` | Event index | probe only |
| `0x1E` | `0xE1` | Event header / first key | probe only |
| `0x0A` | `0xF5` | Waveform header | probe only |
| `0x1A` | `0xE5` | Compliance config | probe only |

### Decoded so far

**`SUB 0x15` — serial.** ASCII, null-terminated: `UM12947`.

**`SUB 0x5B` / `0x01` — identification strings.**
`Instantel\0` and `MM/ISEE/S/IO` (MicroMate / ISEE standard).  `0x01` also
carries eight consecutive `3f 80 00 00` float32 values (= `1.0f`) — almost
certainly per-channel calibration/scale factors, by analogy with Series III's
`geo_hardware_constant`.  **Unverified.**

**`SUB 0x1C` — monitor status.  Series III field offsets apply unchanged:**

| field | offset | read |
|---|---|---|
| battery × 100 | `payload[-10:-8]` uint16 BE | `0x017D` → **3.81 V** |
| memory total | `payload[-8:-4]` uint32 BE | 15,000,000 |
| memory free | `payload[-4:]` uint32 BE | 15,000,000 (empty) |
| date | `payload[18:22]` | day 23, month 9, year `0x07EA` = 2026 |

The battery reading independently corroborates: Thor's own event reports for
these units print `BatteryLevel : 3.8 volts`.

**`SUB 0x2C` — call-home config.** Contains the ASCII string `RADIO RING`.
Worth flagging: that is the *exact* string seen in the RV50 `ALEOS_SERIAL`
debug during the BE12599 incident —
`'ATQ1^MATE0^MATS0=2^M^MRADIO RING^M'`.  So this block holds the modem dial /
answer strings, and it is the most directly relevant command to the
call-home-receiver goal.  Field layout **not yet mapped**; Series III's map
(`raw[5]` enabled, `raw[6:46]` dial string) is a starting hypothesis only, and
the length already differs (`0x7E` vs `0x7C`).

**`SUB 0x06` — storage range.** All zeros on this unit, consistent with
`memory free == memory total`.  Series III reads first/last event keys from
the final 8 bytes; untestable until the unit holds events.

---

## The event chain — walked end to end (2026-09-23, 5 events)

With 5 events on the bench unit (4 waveform + 1 histogram), the Series III
browse walk works unmodified:

```
1E (all-zero params)        -> first key + size
  0A (key)                  -> partial record, histogram only
  0C (key)                  -> 210-byte waveform record
1F (all-zero params/browse) -> next key + size
  ... repeat ...
1F                          -> all-zero key = NULL SENTINEL, chain ends
```

The sentinel terminated correctly after exactly 5 events.

### Event keys are sequential, not addresses

```
055d4a81  055d4a82  055d4a83  055d4a84  055d4a85
```

**This is a real divergence.** Series III keys are flash-buffer *addresses*
(`01110000`, `011121F2`, …) that advance by the event's byte length, which is
why its 5A chunk walk is address-arithmetic. Micromate keys are a plain
incrementing counter. Any port of the Series III download walk must not
assume key arithmetic means anything.

### The 4 bytes after the key are the event's size

`1E`/`1F` return `[key 4B][size 4B]`. Series III uses that slot as an offset
to the next key; here it is a byte count:

| key | size | kind |
|---|---|---|
| `055d4a81` | 4,076 | histogram |
| `055d4a82` | 11,032 | waveform |
| `055d4a83` | 11,502 | waveform |
| `055d4a84` | 13,424 | waveform |
| `055d4a85` | 8,746 | waveform |

Consistent with real file sizes (corpus `.IDFH` ≈ 3.7–25 KB, `.IDFW` ≈
8.6–15.8 KB), and the histogram is unmistakably the small one.  ⚠ Inferred,
not proven: the sizes sum to 48,780 while monitor status reports 57,344 bytes
used, so ~8.5 KB of overhead is unaccounted for.

### `SUB 0x0C` — waveform record, and it carries the job metadata

**Length `0xD2` = 210 bytes — identical to Series III.**  Contents confirmed
across all 5 events:

- the event key, echoed
- date + time (`17 09 07 ea` → 23 Sep 2026, then `10 21` → 16:33 — matching
  the actual bench recording time)
- title note `"Location"`
- **the project string** — `"Univ of Pitt-1st Yr Housing-Loc1 Ruskin"`
- serial `"UM12947"`
- channel labels `Tran` / `Vert` / `Long` / `Mic` — the same labels Series III
  uses, and the same label-relative float32 layout
- per-event float32 peaks: 3.5152, 1.3720, 2.3542, 3.5152, 0.4227 in/s
  across the five events (varied deliberately during recording)

**This closes the biggest open question for the call-home-receiver goal.**
The job identity strings (`project` / `client` / `operator` / `setup`) that
today arrive only via Thor's `.txt` sidecar — and which no amount of sample
decoding can reconstruct — are **available over the wire from `0x0C`**.  A
direct-to-SFM event need not arrive with blank metadata.

### `SUB 0x0A` — partial record, histogram only

`0x0A` returned `len = 0x1E` (30 B) for the histogram and `len = 0x00` for all
four waveforms.  The histogram payload carries **two timestamps** and the
ASCII string `"\r Vert: 0.300 in/s"` — structurally the Series III
**monitor-log partial record** (`0x2C` type), which likewise holds a start/stop
pair and a `"Geo: <float> in/s"` trigger string.

So on the Micromate the division of labour is: `0x0A` describes interval-style
records, `0x0C` describes triggered events.  Series III uses `0x0A`'s
*response length* (`0x46` vs `0x2C`) to tell real events from boundaries;
that discriminator does not apply here.

### DLE stuffing in responses — confirmed present

Earlier marked untested.  The `0x0C` timestamp field contains `10 10`, which
destuffs to a single `0x10` and yields a sensible clock reading.  **Responses
are DLE-stuffed**, so a parser must destuff before applying field offsets.

---

## A/B: Blastware build vs Thor build (2026-09-23)

UM12947 (`11.0CB`) and UM20147 (`11.0BD`) were each put on the bench and given
the identical read-only sweep.  **Both answer Series III command frames.**

| | UM12947 `11.0CB` | UM20147 `11.0BD` |
|---|---|---|
| POLL answers | ✓ | ✓ |
| All 10 read SUBs answer | ✓ | ✓ |
| `response_SUB = 0xFF − req` | ✓ | ✓ |
| DLE-aware checksum valid | ✓ | ✓ |
| Two-step probe/data read | ✓ | ✓ |
| ID string | `MM/ISEE/S/IO` | `MM/ISEE/S` |
| **flags byte** | **`0xC5`** | **`0x03`** |
| **`0x1C` length** | **`0x2C`** | **`0x30`** |

**The firmware line does not change the wire protocol.**  One protocol stack
can drive the whole fleet regardless of which build a unit is on.  This is the
single most consequential finding so far: "standardise the fleet on one
firmware" becomes an *optional* convenience rather than a prerequisite for
building a call-home receiver.

### The two differences that do exist

**1. The flags byte identifies the build.**  Response `payload[1]` is `0xC5`
on the Blastware line and `0x03` on the Thor line, constant across all ten
SUBs on both units.  That makes firmware line detectable from *any* response,
without reading device info.  ⚠ Two units, one each — treat as a strong
hypothesis, not a proven encoding.

Note `0x03` is ETX, so on Thor-line units it arrives DLE-escaped as `10 03`.
A parser that fails to destuff will mis-locate every field by one byte on
exactly half your fleet.

**2. `SUB 0x1C` (monitor status) is 4 bytes longer on the Thor line** —
`0x30` vs `0x2C` — with four extra trailing bytes (`0f a0 00 00`, purpose
unknown).

⚠ **This breaks relative-to-end parsing.**  Series III reads battery and
memory from the *end* of the `0x1C` block (`[-10:-8]`, `[-8:-4]`, `[-4:]`).
Those offsets are correct on `11.0CB` and wrong on `11.0BD` — applying them
blindly to UM20147 yields a battery reading of **577.92 V**.  Parse forward
from the declared length instead of backward from the end.

With the offsets shifted by 4, UM20147 reads correctly: battery **3.81 V**,
memory 15,000,000 total and free (no events stored).

## Divergences from Series III (running list)

1. **No `DLE` prefix on responses** — bare `STX`.
2. **Response flags byte is `0xC5`**, not `0x10`.
3. **Call-home config is 126 bytes**, not 124.
4. **Data lengths are discoverable** from the probe response at `payload[9]`.
4b. **Event keys are a sequential counter**, not flash addresses.
4c. **`1E`/`1F` return the event size**, where Series III returns an offset.
4d. **`0x0A` vs `0x0C` split by record type**, not by the `0x46`/`0x2C`
    length discriminator Series III uses.
4e. **Response `payload[1]` (flags) encodes the firmware line** — `0xC5`
    Blastware, `0x03` Thor — where Series III has a constant `0x10`.
5. **Modem serial rate is 115200**, not 38400 (per TMI provisioning practice;
   not independently verified here).

---

## The firmware images are unencrypted — and they document themselves

`ref-stuff/micromate-firmware/MICROMATE(CB).BIN` and `MICROMATE(BD).BIN`,
~2.77 MB each and within 192 bytes of one another.

- **Entropy 6.08 bits/byte** — neither encrypted nor compressed.  Plain code
  and data.
- Header is a **big-endian vector table**, handlers at `0x4010_30xx`.
- **~16,700 extractable strings**, including the developers' own debug
  `printf` format strings with function names intact.

This is a legitimate interoperability reference for hardware TMI owns, and it
short-circuits work I had scoped as "only answerable from a live modem
capture".

### The call-home state machine, verbatim

```
ACH_NOT_STARTED → ACH_IDLE → ACH_INITIALIZING → ACH_CONNECTING
                → ACH_CONNECTED → ACH_TRANSFER_DATA
                → ACH_RETRY / ACH_QUITTING          (also ACH_STARTED)
```

Supporting strings:

```
ACH: Entry StartCallHome()
ACH: CallHome_task ; CheckAliveTime  CANCEL ; TimeBetweenRetries = %d
ACH: CallHome_task ;  !ExpectedCommunicationsDetected() CANCEL ; TimeBetweenRetries = %d
ACH: CallHomeCommectionCompleteProcessing() ACH=%s EAMWC=%s
ACH: %s() three attempts and it's over
ACH: %s() Send CMD_START_MONITOR
ACH: %s() Send CMD_STOP_MONITOR
ACH: Start Ignore request, Call Home is in progress
```

What this tells us without a single captured packet:

1. **Retry limit is three** — "three attempts and it's over".
2. **`ExpectedCommunicationsDetected()` gates the session.**  If the host does
   not say something the unit recognises, the call is *cancelled* and
   rescheduled after `TimeBetweenRetries`.  A homebrew receiver must satisfy
   this check or units will retry forever — which is exactly the failure mode
   seen on BE12599.
3. **The unit stops monitoring to call home and restarts afterwards**
   (`Send CMD_STOP_MONITOR` / `CMD_START_MONITOR`).  Relevant to any
   wedged-unit rescue: the monitoring state around a call is the device's own
   doing, not ours.
4. **Calls are not re-entrant** — "Call Home is in progress" is ignored.

### Internal command table

`CMD_CALLHOME`, `CMD_CALLHOME_CANCEL`, **`CMD_CALLHOME_CONNECTION_CONFIRMED`**,
`CMD_CALLHOME_CONNECTION_COMPLETE`, `CMD_CALLHOME_SET_SCHEDULE`,
`CMD_CALLHOME_CLEAR_SCHEDULE`, `CMD_STOP_CALLHOME_FILETRANSFER`,
`CMD_DUTYCYCLE_AUTOCALLHOME`, `CMD_PURGE_EVENT_FLASH`.

`CONNECTION_CONFIRMED` as a distinct state from `CONNECTION_COMPLETE` implies
a **handshake the host must complete before data flows** — the concrete shape
of `ExpectedCommunicationsDetected()`.

### Event delivery — the mechanism, probably

```
All Events Uploaded
Mark/Unmark File          Delete Marked Events        Marked Events were Deleted
MONITOR::MESG PURGE_EVENT_FLASH BEGIN / END
```

A **marking** mechanism exists, alongside a distinct "all uploaded" terminal
state.  🔶 **Inferred:** events are *marked* as transferred rather than
deleted on send, and purging is a separate explicit act.  If so, a receiver
that fails to mark would see the same events re-offered every call — the
question that gates a safe homebrew receiver.  **Not yet confirmed**; needs
either a live call-home capture or disassembly around these strings.

### A full user manual is embedded

The firmware carries its own HTML help, which documents configuration we would
otherwise have to infer:

- **Modem mode**: `Generic` (through a modem) vs `USB to PC`.
- **Modem baud**: 9600 / 19200 / 38400 / 57600 / 115200 / 230400 — "must match
  the expected rate of the PC or modem".  Confirms 115200 is a *setting*, not
  a fixed rate.
- **Modem relay + warmup** (0–300 s), auxiliary mode, warning/alarm hold.
- **Record modes**: Waveform, Waveform Manual, Histogram, Histogram-Combo;
  sample rates 1024 / 2048 / 4096.
- **A scheduler downloaded from THOR** that can start/stop monitoring, change
  record mode, trigger a call home, or run a self check on a daily/weekly
  schedule.  Pairs with `CMD_CALLHOME_SET_SCHEDULE`.

### Still worth doing

Diffing the two images should isolate exactly what the CB/BD split changes —
we know the wire protocol is not it, and the flags byte (`0xC5` vs `0x03`)
gives a concrete anchor to search for.

## `SUB 0x5A` — bulk download.  It streams the `.IDFW` file verbatim.

**The complete read path works with no Instantel software in the loop.**

### It needs no arming sequence

Series III ignores a `5A` probe unless preceded by
`1E → 0A → 1E(token 0xFE) → 0C → 1F(token 0xFE) → POLL × 3`.  The Micromate
answers a **bare `5A` request** with nothing before it.  That whole ritual is
gone.

### The offset word is a LENGTH, not a position

This is the key divergence.  Series III walks chunks by absolute flash
address, stepping `0x0200` per request.  On the Micromate the offset word
requests *how much to send*:

```
offset_word = 0x1000 + 2 × pages        pages = ceil(event_size / 512)
```

| `offset_word` | pages | destuffed file bytes |
|---|---|---|
| `0x1002` | 1 | 518 |
| `0x1004` | 2 | 1,030 |
| `0x1006` | 3 | 1,541 |
| `0x102C` | 22 | **11,033 — the whole event** |

`event_size` comes from the chain walk (the 4 bytes after the key in
`1E`/`1F`).  **One request returns the entire event**; there is no chunk loop,
no `STRT` end-offset parsing, and no `TERM` frame.  Over-requesting is safe —
`0x1030` (24 pages) returned exactly the same bytes as `0x102C`, so the device
caps at the real size.

Params are the Series III *probe* form: `[0x00][key4][6 × 0x00]`.

### The payload is the `.IDFW` file, byte for byte

```
[18-byte frame header] [ .IDFW file ] [chk] [ETX]     ← raw wire
                        ^ destuffed offset 16
```

The file begins `00 12 01 00 00 00 "Instantel\0"` — `_THOR_PREFIX` +
`_INSTANTEL_TAG` from `micromate/idf_file.py`.  The first 32 bytes are
**identical to a production `.IDFW`** pulled from the store.

⚠ Responses are DLE-stuffed.  Destuff before locating the file, or the raw
byte count overshoots (11,781 raw → 11,049 destuffed for an 11,032-byte event).

### End-to-end proof

Event `055d4a82` downloaded over USB and fed straight to `read_idf_file()`:

```
serial     UM12947
timestamp  2026-09-23 16:33:19
samples    Tran 3072   Vert 3072   Long 3072   MicL 3072
peaks      Tran 0.2433   Vert 1.3706   Long 0.2672  in/s
```

All four channels equal length, and the timestamp matches the `0x0C` record
for the same key.  **Independent cross-check:** `0x0C` reports a stored peak
of **1.3720** for this event; the decoded samples give **1.3706** — two
unrelated paths agreeing to 0.1%.

**Consequence:** no new codec work is needed.  The bytes off the wire are the
same bytes `thor-watcher` forwards today, so `/db/import/idf_file` ingests a
directly-downloaded event unchanged.  Everything the IDF decoder already does
per-sample-exact applies.

### What a full read now looks like

```
1E                     → first key + size
  0C(key)              → project/client/operator, timestamp, peaks
  5A(key, 0x1000+2×ceil(size/512))  → the whole .IDFW
1F                     → next key + size   (until null sentinel)
```

## Setups are FILES, not a config block

Series III has one compliance config you overwrite.  Series IV keeps **named
setup files on an on-device filesystem**, with a pointer to the current one.
From the firmware:

```
csetup.MMB              the current setup
factory.MMB             Factory Default Setup File
callhome.MMB            call-home config is a file too
"Current Setup File:  "         "Can Not Delete Active Setup File"
GetSelectedSetupFilePathName()  CSelectSetupFiles  CSaveSetupFile
```

Names are up to 20 characters and may contain spaces, hyphens, underscores.
The unit's help text describes selecting, renaming and deleting them, and the
event list records which setup file produced each event.

Filesystem primitives exist internally (`NS_ReadFile_internal`,
`NS_WriteFile_internal`, `NS_SeekFile_internal`), but **no generic
file-transfer command is exposed on the wire** — the only file-transfer string
is `CMD_STOP_CALLHOME_FILETRANSFER`.  So setups are unlikely to be pushed as
raw `.MMB` blobs over the protocol.

### `SUB 0x1A` reads the whole active setup — 2,092 bytes

Structurally close to Series III's ~2,126-byte compliance block, and it
carries everything a setup consists of:

- **the setup file name** — `Univ of Pitt-1st Yr. Housing-Loc1 Ruskin.MMB`
- all four title note/value pairs — `Location`, `Client`, `Company`,
  `General Notes`, with their strings
- the sensor location string (`Loc 1`)
- per-channel labels *and units*: `Tran in./s.`, `Vert in./s.`,
  `Long in./s.`, `Mic psi (L)`, `LMic psi (L)`, `SMic (A)`

Note `LMic` / `SMic` — linear and sound-level microphone variants that
Series III does not have.

This is the **read half of setup management**, and it means a setup can be
round-tripped: read the active config, modify, write it back.  The write half
is not yet attempted.

## ⚠ Untested and unsafe-until-agreed

Nothing below has been sent to a unit, and nothing should be without an
explicit decision:

- **Writes** (`0x68`–`0x83`), **call-home write** (`0x7E`/`0x7F`)
- **Erase** (`0xA3` / `0xA2`)
- **Start / stop monitoring** (`0x96` / `0x97`)
- `0x1F` (advance event pointer) — non-destructive on Series III but it does
  move device state, so it is parked with the rest

Also unknown:

- Whether `0x10` bytes inside request params need stuffing
- Everything about the **call-home session** — the device-initiated direction
  has not been observed at all.  Specifically: how a unit announces itself,
  and **how it learns an event was accepted so it stops re-sending it.**
  That last question gates any homebrew receiver and cannot be answered over
  USB.

---

## Session provenance

Unit **UM12947**, firmware **`11.0CB`** (Blastware line), on the bench via
USB, **zero events stored** (memory free == total).  Read commands only.
Every response in this document was checksum-validated.

⚠ Firmware is the single biggest caveat on this document.  Every finding here
is from one unit on the Blastware build.  A `11.0BD` unit has not been
touched.

An empty unit is a real limitation: `0x08`, `0x1E`, `0x0A` and `0x06` all have
event-dependent payloads that could not be exercised.  Recording a couple of
events on the bench unit would unlock the entire event-walk half of the
protocol.