Add environment-driven digital probe mode

.env.example

@@ -39,6 +39,20 @@ UART_STOP_BITS=1
 UART_TX_GPIO=20
 UART_RX_GPIO=21
 
+# ---------- Read-only development probe ----------
+# Keep disabled until a safe, conditioned front-panel signal is connected.
+PROBE_ENABLED=false
+# Required when PROBE_ENABLED=true. GPIO3 is a candidate on the C3 Super Mini,
+# but confirm the board routing and electrical interface before using it.
+PROBE_GPIO=
+# state | frequency | pulse | watch
+PROBE_MODE=frequency
+PROBE_INTERVAL_SECONDS=3
+PROBE_FREQUENCY_SECONDS=2
+PROBE_PULSE_TIMEOUT_US=1000000
+PROBE_WATCH_SECONDS=5
+PROBE_WATCH_MAX_EVENTS=200
+
 # ---------- Self-update ----------
 UPDATE_ENABLED=true
 

docs/DIGITAL_PROBE.md

@@ -38,6 +38,25 @@ probe.pulse(timeout_us=1_000_000)
 probe.watch(seconds=5, max_events=200)
 ```
 
+## Continuous probe mode
+
+To collect data without interrupting the application, set the following in the
+device-local `/.env` and reset the board:
+
+```env
+PROBE_ENABLED=true
+PROBE_GPIO=3
+PROBE_MODE=frequency
+PROBE_FREQUENCY_SECONDS=2
+PROBE_INTERVAL_SECONDS=3
+```
+
+`PROBE_MODE` may be `state`, `frequency`, `pulse`, or `watch`. The corresponding
+`PROBE_*` settings in `.env.example` control the measurement window, timeout,
+or event cap. The mode continuously writes its results to the serial console;
+it does not expose any output pin or machine-control capability. Set
+`PROBE_ENABLED=false` and reset to return to normal application operation.
+
 `frequency()` counts rising edges in its measurement window. It is useful for
 signal discovery and approximate rates, but very fast or noisy signals can
 overflow or exceed MicroPython IRQ handling capacity. `pulse()` reports one

firmware/app/main.py

@@ -10,6 +10,63 @@ except ImportError:
     import asyncio
 
 
+def as_bool(value, default=False):
+    if value is None:
+        return default
+    return str(value).strip().lower() in ("1", "true", "yes", "on", "enabled")
+
+
+def as_int(value, default=0, minimum=None):
+    try:
+        result = int(str(value).strip())
+    except Exception:
+        result = default
+    if minimum is not None:
+        result = max(minimum, result)
+    return result
+
+
+async def run_probe_mode(ctx):
+    """Continuously collect read-only probe data while the app keeps running."""
+    env = ctx["env"]
+    pin_text = env.get("PROBE_GPIO", "").strip()
+    if not pin_text:
+        raise RuntimeError("PROBE_ENABLED=true requires PROBE_GPIO")
+    try:
+        pin_id = int(pin_text)
+    except Exception:
+        raise RuntimeError("PROBE_GPIO must be an integer GPIO number")
+
+    mode = env.get("PROBE_MODE", "frequency").strip().lower()
+    if mode not in ("state", "frequency", "pulse", "watch"):
+        raise RuntimeError("Unknown PROBE_MODE=" + mode)
+
+    from app.digital_probe import open_probe
+    probe = open_probe(pin_id)
+    frequency_seconds = as_int(env.get("PROBE_FREQUENCY_SECONDS"), 2, 1)
+    watch_seconds = as_int(env.get("PROBE_WATCH_SECONDS"), 5, 1)
+    watch_events = as_int(env.get("PROBE_WATCH_MAX_EVENTS"), 200, 1)
+    pulse_timeout_us = as_int(env.get("PROBE_PULSE_TIMEOUT_US"), 1_000_000, 1)
+    interval_seconds = as_int(env.get("PROBE_INTERVAL_SECONDS"), 3, 1)
+    activity = ctx["activity"]
+
+    print("[probe] mode=%s interval=%ss" % (mode, interval_seconds))
+    while True:
+        # Measurements are data collection, not a machine action, but marking
+        # activity prevents an OTA reboot from interrupting a capture.
+        activity.touch()
+        if mode == "state":
+            probe.state()
+        elif mode == "frequency":
+            probe.frequency(frequency_seconds)
+        elif mode == "pulse":
+            probe.pulse(pulse_timeout_us)
+        else:
+            probe.watch(watch_seconds, watch_events)
+        activity.touch()
+        await asyncio.sleep_ms(interval_seconds * 1000)
+
+
 async def setup(ctx):
     # Configure GPIOs, state machines, etc. here.
     # If this raises immediately after an OTA, boot.py can roll back.
@@ -17,6 +74,10 @@ async def setup(ctx):
 
 
 async def main(ctx):
+    if as_bool(ctx["env"].get("PROBE_ENABLED"), False):
+        await run_probe_mode(ctx)
+        return
+
     activity = ctx["activity"]
     uart = ctx["uart"]
 

firmware/manifest.json

@@ -1,6 +1,6 @@
 {
   "schema": 1,
-  "release": "0.1.1-probe.1",
+  "release": "0.1.2-probe.2",
   "files": [
     {
       "source": "firmware/launcher.py",
@@ -20,7 +20,7 @@
     {
       "source": "firmware/app/main.py",
       "target": "/app/main.py",
-      "sha256": "5b287d984df266007df4014ece8e323339c0da594f4c88bcf4a6da1ff067a16f"
+      "sha256": "7eaa8b4b8f213f44a080c82a1f76c8981b06458fa4b05e239a7d6c8cdc114c18"
     }
   ]
 }