# MCC E-1608 source plugin (sub-project 3 of 4) Date: 2026-10-31 Branch: `feature/source-e1608` (from `feature/source-plugins`, sub-project 1) ## Context Sub-project 1 added the `DataSource` / `SourceKind` / `SourceRegistry` framework and ported UDPS onto it. This sub-project adds a second kind, `e1608`: the Measurement Computing E-1608 Ethernet DAQ (8 SE / 4 DIFF 16-bit analog inputs, 2 analog outputs, 8 DIO bits, one 32-bit counter), with its own connect form and two side-stack panels. References for the wire protocol, both written by the user: - Primary: `~/Projects/marte2_projects/MCC_E1608_DataSource`, a MARTe2 DataSource (`E1608DataSource.{h,cpp}`, `E1608ScanFifo`). Its class comment in the header is the authoritative list of parameters and behaviour. It is bound to MARTe2 (`BasicTCPSocket`, `StreamString`, `SingleThreadService`), so it is **ported** to plain C++, not linked. - Cross-check: `~/Projects/uopi/internal/datasource/mcc/{protocol,e1608}.go`, an independent Go implementation of the same protocol. No board is available. The mock is the only verification until one is attached. ## Decisions | Question | Decision | | --- | --- | | DAC / generator | Static level plus a software waveform (sine, square, triangle, ramp), 10 Hz at most. Runs as a timer inside `poll()`; no extra thread. | | Hardware | None available. A protocol mock (`tools/mock_e1608.py`) is the contract. Commands whose layout rests on a single reference (or where the two disagree) are listed as unverified. | | Analog input config | Full: per-channel enable and range, global SE/DIFF, MAC discovery, external clock, trigger, DI/counter poll rate. | | Digital lines and counter | Plot channels the user chooses, off by default, enabled per line in the connect form. | | Acquisition modes | Hardware-paced only (scan rate or external clock). Software-paced mode (`ScanRate = 0`) is not ported. | | Structure | Three layers: link, device, source. The bottom two have no GTK or `DataSource` types. | ## Design ### 1. Files (new, `src/source/e1608/`, plus the mock) - `e1608_link.{hpp,cpp}`: UDP discovery (broadcast, or a unicast sweep of a given subnet matched by MAC and the E-1608 product id) and connection-code handshake; TCP command framing with a timeout; the scan socket on `port + 1`. Plain POSIX sockets. - `e1608_device.{hpp,cpp}`: typed commands (AI, AO, DIO read/write/direction, counter read/reset, scan queue, scan start/stop, status), the factory calibration read from the board's calibration memory, and `decode()`, which turns raw interleaved `uint16` scans into calibrated volts (`double`). - `e1608_source.{hpp,cpp}`: the `DataSource`: the `poll()` state machine, `Frame` building, the DI/counter and generator timers, the atomic readouts for the panels. - `e1608_kind.cpp`: the `SourceKind`: the connect form and the two panels. - `tools/mock_e1608.py`: the protocol mock. - `register_builtin_sources()` registers `e1608` after `udps`. ### 2. Data path and threading Everything runs inside `poll()` on the producer thread. The GTK thread reaches the board only through `post(Command)`. `poll(timeout)`: 1. Drains the posted commands (DAC writes, DIO toggles, counter reset, generator edits). 2. Runs the connection state machine: optional MAC lookup, handshake, calibration read, DIO direction and initial outputs, scan queue and scan start take Disconnected to Scanning. A link error fires `on_event(Disconnected)` and retries every 2 s. A connect attempt can block `poll()` for up to the command timeout; that delays only the command queue. 3. Waits on the scan socket for at most the time to the next timer, reads what arrived, keeps a partial scan for the next call, decodes the complete scans with the calibration and delivers a `Frame`. 4. Runs the due timers: the DI/counter poll (`DiPollRate`) is a command round trip; the generator tick (at most 10 Hz) is a DAC write. The frame: - Signals: the enabled AI channels (unit `V`, `range_min`/`range_max` from the channel's range), the DI lines the user chose (0/1), and the counter if chosen. - All signals are scalar; `num_samples` is the number of scans decoded in that read. - DI and counter values are held across the block (a step trace). - `sampling_rate` is the scan rate on every signal. `counter` is a running frame count. - The aggregate rate (enabled channels times scan rate) must stay at or below 250 kS/s. The form refuses a configuration above it. Overrun: if the board reports a scan overrun the source fires `on_event(Error)` and restarts the scan when `AutoRestart` is set; the next frame carries `lost = 1`. This is approximate, because the board does not report how many scans it dropped. Panel readouts: the source keeps the live DIO inputs, the counter, the DAC levels and the generator state in atomics. The panels read them from a GTK timer, so no widget touches the source's internals. ### 3. Connect form and panels Connect form: grouped `AdwExpanderRow`s in the chooser's group. `SourceConfig` stays flat; a per-channel setting is a key such as `ai0=BIP10V` (absent means off). - Connection: address, MAC, discovery subnet, port, connection code, timeout. `valid()` needs an address, or a MAC plus a subnet. - Acquisition: scan rate, external clock, trigger mode, auto-restart, calibrate (default on), DI/counter poll rate. - Analog inputs: global SE or DIFF mode and 8 channel rows (enable, range). In DIFF mode rows 4 to 7 are insensitive, not hidden. `valid()` also enforces the 250 kS/s aggregate. - Digital I/O: direction per bit (I or O), a "plot" switch per input bit, a "plot counter" switch, the initial DO value and the initial DAC levels. `identity()` is the address, or the MAC when there is no address. A session file is named `e1608-`, port 1, as sub-project 1 defines for non-UDPS kinds. `has_datagrams()` is false, so the capture button is disabled. Two side-stack panels, both insensitive while disconnected (disabled, not hidden): - Analog out: per DAC, a mode (Level, Sine, Square, Triangle, Ramp), a level or amplitude plus offset, a frequency of 0.1 to 10 Hz, and an on/off switch. It shows the last voltage written and clamps to ±10 V. The generator stops on disconnect and the DACs return to their initial levels on reconnect. - Digital I/O: eight bit rows; an input bit shows a live LED, an output bit has a toggle that posts a write. The counter shows its value and a Reset button. Directions come from the form and are not changed at runtime. Tab icons are chosen in the plan under the project's bundled-icon rules. ### 4. Verification Mock (`tools/mock_e1608.py`): UDP discovery with a MAC and the connection-code handshake; TCP commands for AI, AO, DIO, the counter, scan queue, scan start/stop, calibration memory and status; a scan stream on port+1 at the requested rate with a sine per channel; switches to drop the link after N seconds and to report an overrun. Its header lists every command whose layout is unverified (single reference, or the references disagree). Probe `UDPSCOPE_PROBE_E1608=`, run against the mock with `--source e1608`, extends the probe/dump in `src/ui.cpp`. It checks: - Frames arrive with the expected channel count and sample rate. - The panels are present and insensitive while disconnected. - A DAC write, a DIO toggle and a counter reset each reach the mock. - A forced link drop leads to a reconnect and a resumed stream. - The calibration is applied (the mock serves non-trivial coefficients). A decode check needs no mock: a fixed raw buffer decoded against hand-computed volts. Baselines are unchanged: the UDPS self-check reads as on `main`, exactly three build warnings, no `Gtk-CRITICAL`. Errors: a rejected handshake (bad connection code), no device found, timeouts and scan-socket loss surface through `on_event(Error)` with a readable message and follow the reconnect cycle. A rejected connection code stops the retries: the source stays in Error with that message until the user reconnects. Docs: update `architecture.md`, `build-and-run.md`, `verification.md`, `probe-readings.md` and `README.md`. ## Out of scope - Software-paced acquisition (`ScanRate = 0`). - A generator faster than 10 Hz, and a dedicated I/O thread. - Changing DIO directions at runtime. - Per-channel SE/DIFF mixing (one global mode). - Verification against a real board.