fix: HistoryCodec mask width for 16 sensors + enable mDNS

- HistoryCodec.h/cpp: changed field mask from uint16_t (2 bytes, 16 bits)
  to uint32_t (3 bytes, 18 bits). With MAX_SENSORS=16, the mask needs
  2 ambient + 16 sensor = 18 bits. Sensors 14-15 were silently truncated
  in delta records. Updated HIST_V2_MAX_DELTA_SIZE 58→62 bytes.
- test_history_codec: updated assertions for 3-byte mask and 40-byte
  anchor (was expecting old 28-byte record size).
- platformio.ini: enabled mDNS (-DSIMUT_MDNS=1). Cost: ~15KB flash.
- All 51 tests passing (29 validators + 22 HistoryCodec).

Author: angeloINTJ

CHANGELOG.md

@@ -29,11 +29,19 @@ All notable changes to SIMUT firmware.
 - **`PIN_ONEWIRE_DEFAULT`** — Fixed preprocessor redefinition warning (8 instances eliminated).
 - **All 4 sensor channels initialized** — `MAX_SENSOR_CHANNELS` loop sets `avgValue` to NAN and `calibrationOffset` to 0.
 
+### Other Changes
+
+- **mDNS enabled by default** — `-DSIMUT_MDNS=1` in platformio.ini. Device accessible via `http://simut.local`. Cost: ~15KB flash, negligible RAM.
+- **I2C0/I2C1 auto-detection** — `i2cPeripheralForPins()` selects the correct peripheral at runtime. Any GPIO 0-15 pair works for I2C sensors (hardware permitting).
+- **`checkAndAutoHealSensors()`** — No longer reports false "Sensor missing" warnings for non-DS18B20 sensor types (DHT22, BME280).
+- **BME280 boot guard** — I2C timeout (50ms) + ACK probe prevents boot hang when BME280 is configured but not physically connected.
+- **Hardcoded GPIO assumptions removed** — DHT22 `begin()` no longer references GPIO 10. DS18B20 legacy methods use first active sensor's pin. Zero fixed GPIO-to-type coupling.
+
 ### Flash Budget
 
-- **Without BME280**: 91.6% (957KB / 1044KB)
-- **With BME280**: 92.3% (964KB / 1044KB) — ~7KB for BME280 driver
-- **RAM**: 35.7-35.8% (~93.5KB / 262KB)
+- **Release (DS18B20 + DHT22 + mDNS)**: 93.1% (972KB / 1044KB) — ~72KB free
+- **With BME280**: 93.7% (979KB / 1044KB) — ~65KB free
+- **RAM**: 35.7% (~93.7KB / 262KB)
 
 ## v1.4.3-beta (2026-06-07)
 

platformio.ini

@@ -52,6 +52,7 @@ build_flags =
     -Wl,-u,_printf_float
     -DSIMUT_SENSOR_DS18B20=1
     -DSIMUT_SENSOR_DHT22=1
+    -DSIMUT_MDNS=1
 
 ; --- External libraries (pinned for reproducibility) ---
 lib_deps =

src/HistoryCodec.cpp

@@ -82,18 +82,20 @@ size_t historyEncodeRecord(const BinaryHistoryRecord& rec,
  /* DELTA */
  uint8_t* p = buf;
 
- /* Mask: bit 0=amb_temp, bit 1=amb_hum, bit 2..17=sensors[0..15]. */
- uint16_t mask = 0;
- if (rec.ambientTemp != HIST_NAN_SENTINEL) mask |= (1u << 0);
- if (rec.ambientHum != HIST_NAN_SENTINEL) mask |= (1u << 1);
+ /* Mask: bit 0=amb_temp, bit 1=amb_hum, bit 2..17=sensors[0..15].
+  * Uses 3 bytes (18 bits) — uint32_t to fit all 16 sensor slots. */
+ uint32_t mask = 0;
+ if (rec.ambientTemp != HIST_NAN_SENTINEL) mask |= (1ul << 0);
+ if (rec.ambientHum != HIST_NAN_SENTINEL) mask |= (1ul << 1);
  for (int i = 0; i < MAX_SENSORS; i++) {
- if (rec.sensors[i] != HIST_NAN_SENTINEL) mask |= (1u << (2 + i));
+ if (rec.sensors[i] != HIST_NAN_SENTINEL) mask |= (1ul << (2 + i));
  }
 
- if ((size_t)(p - buf) + 2 > bufSize) return 0;
+ if ((size_t)(p - buf) + 3 > bufSize) return 0;
  p[0] = (uint8_t)(mask & 0xFF);
- p[1] = (uint8_t)((mask >> 8) & 0x0F); /* ensure top 4 bits = 0 */
- p += 2;
+ p[1] = (uint8_t)((mask >> 8) & 0xFF);
+ p[2] = (uint8_t)((mask >> 16) & 0x03); /* only bits 16-17 used */
+ p += 3;
 
  /* Δepoch always present. In normal use = configured interval (1B). */
  int32_t depoch = (int32_t)rec.epoch - (int32_t)s.lastValid.epoch;
@@ -108,19 +110,19 @@ size_t historyEncodeRecord(const BinaryHistoryRecord& rec,
  return true;
  };
 
- if (!encField(mask & (1u << 0), s.fieldHasValid[0], rec.ambientTemp, s.lastValid.ambientTemp)) return 0;
- if (!encField(mask & (1u << 1), s.fieldHasValid[1], rec.ambientHum, s.lastValid.ambientHum)) return 0;
+ if (!encField(mask & (1ul << 0), s.fieldHasValid[0], rec.ambientTemp, s.lastValid.ambientTemp)) return 0;
+ if (!encField(mask & (1ul << 1), s.fieldHasValid[1], rec.ambientHum, s.lastValid.ambientHum)) return 0;
  for (int i = 0; i < MAX_SENSORS; i++) {
- if (!encField(mask & (1u << (2 + i)), s.fieldHasValid[2 + i],
+ if (!encField(mask & (1ul << (2 + i)), s.fieldHasValid[2 + i],
  rec.sensors[i], s.lastValid.sensors[i])) return 0;
  }
 
  /* Update state only for fields actually present. */
  s.lastValid.epoch = rec.epoch;
- if (mask & (1u << 0)) { s.lastValid.ambientTemp = rec.ambientTemp; s.fieldHasValid[0] = true; }
- if (mask & (1u << 1)) { s.lastValid.ambientHum = rec.ambientHum; s.fieldHasValid[1] = true; }
+ if (mask & (1ul << 0)) { s.lastValid.ambientTemp = rec.ambientTemp; s.fieldHasValid[0] = true; }
+ if (mask & (1ul << 1)) { s.lastValid.ambientHum = rec.ambientHum; s.fieldHasValid[1] = true; }
  for (int i = 0; i < MAX_SENSORS; i++) {
- if (mask & (1u << (2 + i))) {
+ if (mask & (1ul << (2 + i))) {
  s.lastValid.sensors[i] = rec.sensors[i];
  s.fieldHasValid[2 + i] = true;
  }
@@ -148,11 +150,11 @@ size_t historyDecodeRecord(const uint8_t* buf, size_t bufLen,
  return sizeof(BinaryHistoryRecord);
  }
 
- if (bufLen < 2) return 0;
+ if (bufLen < 3) return 0;
  const uint8_t* p = buf;
 
- uint16_t mask = (uint16_t)p[0] | ((uint16_t)p[1] << 8);
- p += 2;
+ uint32_t mask = (uint32_t)p[0] | ((uint32_t)p[1] << 8) | ((uint32_t)p[2] << 16);
+ p += 3;
 
  int32_t depoch = 0;
  size_t n = readVarintZ(p, bufLen - (size_t)(p - buf), depoch);
@@ -172,22 +174,22 @@ size_t historyDecodeRecord(const uint8_t* buf, size_t bufLen,
  };
 
  int16_t tmpTemp = HIST_NAN_SENTINEL, tmpHum = HIST_NAN_SENTINEL;
- if (!decField(mask & (1u << 0), s.fieldHasValid[0], s.lastValid.ambientTemp, &tmpTemp)) return 0;
- if (!decField(mask & (1u << 1), s.fieldHasValid[1], s.lastValid.ambientHum, &tmpHum)) return 0;
+ if (!decField(mask & (1ul << 0), s.fieldHasValid[0], s.lastValid.ambientTemp, &tmpTemp)) return 0;
+ if (!decField(mask & (1ul << 1), s.fieldHasValid[1], s.lastValid.ambientHum, &tmpHum)) return 0;
  outRec.ambientTemp = tmpTemp;
  outRec.ambientHum = tmpHum;
  for (int i = 0; i < MAX_SENSORS; i++) {
  int16_t tmpS = HIST_NAN_SENTINEL;
- if (!decField(mask & (1u << (2 + i)), s.fieldHasValid[2 + i],
+ if (!decField(mask & (1ul << (2 + i)), s.fieldHasValid[2 + i],
  s.lastValid.sensors[i], &tmpS)) return 0;
  outRec.sensors[i] = tmpS;
  }
 
  s.lastValid.epoch = outRec.epoch;
- if (mask & (1u << 0)) { s.lastValid.ambientTemp = outRec.ambientTemp; s.fieldHasValid[0] = true; }
- if (mask & (1u << 1)) { s.lastValid.ambientHum = outRec.ambientHum; s.fieldHasValid[1] = true; }
+ if (mask & (1ul << 0)) { s.lastValid.ambientTemp = outRec.ambientTemp; s.fieldHasValid[0] = true; }
+ if (mask & (1ul << 1)) { s.lastValid.ambientHum = outRec.ambientHum; s.fieldHasValid[1] = true; }
  for (int i = 0; i < MAX_SENSORS; i++) {
- if (mask & (1u << (2 + i))) {
+ if (mask & (1ul << (2 + i))) {
  s.lastValid.sensors[i] = outRec.sensors[i];
  s.fieldHasValid[2 + i] = true;
  }

src/HistoryCodec.h

@@ -4,7 +4,8 @@
  * @details Format replaces the fixed 40 B/record of v1 with:
  * - 16 B header per file (magic SIM2 + version + anchorPeriod)
  * - 1 anchor (full 40 B record) every N=60 records
- * - 59 variable deltas between anchors (typical ~7-18 B each)
+ * - 59 variable deltas between anchors (typical ~7-19 B each)
+ * - 3-byte field mask (18 bits: 2 ambient + 16 sensor slots)
  *
  * Typical compression 3-4x for common usage (few active sensors +
  * small temperature variation between samples). Reader is linear:
@@ -26,7 +27,7 @@ constexpr char HIST_V2_MAGIC[4] = {'S','I','M','2'};
 constexpr uint16_t HIST_V2_VERSION = 0x0002;
 constexpr uint16_t HIST_V2_ANCHOR_PERIOD = 60; /* 1 anchor + 59 deltas (= 1 hour @ 1 min) */
 constexpr size_t HIST_V2_HEADER_SIZE = 16;
-constexpr size_t HIST_V2_MAX_DELTA_SIZE = 58; /* worst-case: 2B mask + 5B Δepoch + 18*3B varints */
+constexpr size_t HIST_V2_MAX_DELTA_SIZE = 62; /* worst-case: 3B mask + 5B Δepoch + 18*3B varints */
 
 struct __attribute__((packed)) HistoryFileHeaderV2 {
  char magic[4]; /* "SIM2" */
@@ -59,7 +60,7 @@ void historyCodecReset(HistoryCodecState& s);
 /* ENCODER / DECODER */
 /* ======================================================================== */
 
-/** Encode a record. Automatically decides between anchor (28 B fixed) or
+/** Encode a record. Automatically decides between anchor (40 B fixed) or
  * variable delta based on recordsSinceAnchor.
  *
  * @param rec Input record (in-memory uncompressed).
@@ -83,7 +84,7 @@ size_t historyEncodeRecord(const BinaryHistoryRecord& rec,
  * @param bufLen Buffer size.
  * @param s Decoder state (updated in-place).
  * @param outRec Reconstructed record.
- * @param isAnchor true if this record is an anchor (28 B fixed).
+ * @param isAnchor true if this record is an anchor (40 B fixed).
  * @return Bytes consumed, or 0 on error (truncated buffer).
  */
 size_t historyDecodeRecord(const uint8_t* buf, size_t bufLen,

test/test_history_codec/test_main.cpp

@@ -533,8 +533,8 @@ void test_nanFieldsOmittedFromDelta(void) {
 	rec.epoch += 60;
 	size_t written = historyEncodeRecord(rec, state, buf, sizeof(buf), nullptr);
 
-	/* Delta should be minimal: 2B mask + 1B epoch varint = 3 bytes */
-	TEST_ASSERT_EQUAL_size_t(3, written);
+	/* Delta should be minimal: 3B mask + 1B epoch varint = 4 bytes */
+	TEST_ASSERT_EQUAL_size_t(4, written);
 }
 
 
@@ -543,7 +543,7 @@ void test_nanFieldsOmittedFromDelta(void) {
 /* =========================================================================== */
 
 void test_bufferTooSmall_anchor(void) {
-	/* Anchor requires sizeof(BinaryHistoryRecord) = 28 bytes.
+	/* Anchor requires sizeof(BinaryHistoryRecord) = 40 bytes.
 	 * Offering less must return 0 (error). */
 	HistoryCodecState state;
 	historyCodecReset(state);