chore: release 1.5.1

The TX state machine's `prep_for_cad_act` (TxCadPrep entry) and
`prep_for_tx_act` (TxPrep entry) both read `ctx.mdltn` and emit
`TransmitFailed` → `ERR(ERadio)` if it's None. But `ctx.mdltn` was
only ever assigned on the RX path — `try_start_rx_hw` (RxArming entry)
and `cache_rx_pkt` (RxSession entry). `reconfigure_radio` already
called `to_lora_mod_params(lora, cfg)` during SET_CONFIG but discarded
the result via `let _ = …?;` (comment claimed image calibration; the
function is pure compute on SX126x).

Result: a freshly-booted dongle that issues TX before ever calling
RX_START gets `ERR(ERadio)` on the first CmdTx because the chart's
TX-entry actions find `ctx.mdltn = None`. The bug was hidden in
practice by any prior RX_START (ai-bot, ping_pong --role rx, etc.)
leaving `ctx.mdltn` populated across sessions until the next reflash.

Fix: thread the `ModulationParams` out of `reconfigure_radio` as its
return value, and have `apply_set_config` cache it in `self.mdltn`
alongside `self.config`. The failure path clears `self.mdltn` along
with `self.config` so a SET_CONFIG that fails leaves a clean
Unconfigured state.

Surfaced while testing the matching sync-word fix on freshly-flashed
dongles via `examples/sync_word_test.py` — the first TX failed with
`ERR(ERadio)` until this path was wired up.

CHANGELOG.md

@@ -7,6 +7,64 @@ and this project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+## [1.5.1] - 2026-05-11
+
+### Fixed
+
+- **`LoRaConfig.sync_word` is now actually applied to the SX126x.**
+  `reconfigure_radio` accepted the host's `sync_word` field in name
+  only — the value was stored in `self.config` but never written to
+  the chip's `LoRaSyncwordMSB`/`LoRaSyncwordLSB` register pair
+  (0x0740/0x0741, SX1261/2 datasheet Rev 2.2 §13.4.4). The chip sat
+  on whatever `LoRa::new(_, false, _)` set at cold init —
+  `LORAWAN_PRIVATE_SYNCWORD` (byte `0x12`, register pair `0x1424`).
+  Everyone got byte `0x12` regardless of the requested value. Worked
+  by accident for MeshCore (which uses byte `0x12`); silently broke
+  any host trying to talk to a non-MeshCore network. Fix wires
+  `cfg.sync_word` through to `lora.set_lora_sync_word(byte)` after
+  `enter_standby`, using the new lora-phy API from
+  [lora-rs/lora-rs#433](https://github.com/lora-rs/lora-rs/pull/433).
+  The `u16` protocol field is decoded back to its underlying byte
+  (`byte = (hi & 0xF0) | (lo >> 4)` after `to_be_bytes()`), the
+  inverse of lora-phy's `convert_sync_word` nibble-expansion. Honors
+  SX1261/2 §8.3.1 (BUSY-low precondition) via the existing
+  `ensure_ready + conditional set_standby` preamble in
+  `LoRa::set_lora_sync_word`.
+- **First TX after `SET_CONFIG` no longer fails with `ERR(ERadio)` on
+  a freshly-booted chip.** The chart's `prep_for_cad_act`
+  (`TxCadPrep` entry) and `prep_for_tx_act` (`TxPrep` entry) both
+  read `ctx.mdltn` and emit `TransmitFailed` → `ERR(ERadio)` if it's
+  `None`. But `ctx.mdltn` was only ever assigned on the RX path —
+  `try_start_rx_hw` (`RxArming` entry) and `cache_rx_pkt`
+  (`RxSession` entry). `reconfigure_radio` already called
+  `to_lora_mod_params(lora, cfg)` during `SET_CONFIG` but discarded
+  the result via `let _ = …?;` (the dropped comment claimed image
+  calibration; the function is pure compute on SX126x). Hidden in
+  practice by any prior `RX_START` (ai-bot, `ping_pong --role rx`,
+  etc.) leaving `ctx.mdltn` populated until the next reflash. Fix
+  threads the `ModulationParams` out of `reconfigure_radio` as its
+  return value, and `apply_set_config` caches it in `self.mdltn`
+  alongside `self.config`. First TX on a fresh boot now works
+  without a preceding `RX_START`.
+
+### Changed
+
+- **`lora-phy` `swaits/lora-rs#fixed` bumped from `e8a52ebd` →
+  `043d7659`.** The fork's `fixed` merge now includes a new
+  `feat/set-sync-word` branch alongside the three pre-existing
+  `fix/*` branches.
+  [lora-rs/lora-rs#433](https://github.com/lora-rs/lora-rs/pull/433)
+  adds the runtime `LoRa::set_lora_sync_word(u8)` API the radio fix
+  above depends on (was unavailable in stock lora-phy; the only
+  public sync-word entry points were `with_syncword` /
+  `new(_, public_network: bool, _)` at construction time). Strictly
+  additive in lora-phy: pure addition, no behavioral change to
+  `init_lora` / `with_syncword` / any existing path.
+- **`hsmc` 0.5 → 0.6.** Patch bump tracked via `cargo update -p
+  hsmc`; no behavior change in this crate's usage. Pulled in
+  separately from the radio fixes so the dep churn doesn't blur the
+  fix commits.
+
 ## [1.5.0] - 2026-04-30
 
 ### Added

Cargo.lock

@@ -586,7 +586,7 @@ dependencies = [
 
 [[package]]
 name = "donglora"
-version = "1.5.0"
+version = "1.5.1"
 dependencies = [
  "cfg-if",
  "cortex-m",
@@ -1592,9 +1592,9 @@ checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
 
 [[package]]
 name = "hsmc"
-version = "0.5.1"
+version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "497ed9593e4baf6ef120b24aff80cb898f6832d32cdf01be9d90be0c06624e77"
+checksum = "18bb06fda289e60e17bc7483a222fc6d9d6865b92648f836242b7a79115cc91d"
 dependencies = [
  "defmt 0.3.100",
  "embassy-futures",
@@ -1606,9 +1606,9 @@ dependencies = [
 
 [[package]]
 name = "hsmc-macros"
-version = "0.5.1"
+version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "49d0b1413ed69ba168f9d0edbf4a8ea21569eaf352edf4e11335ae3d765ba004"
+checksum = "289a7c9f1b677168229c8ad4e992380c3951d0908b52b1d2bfae8ff3c980c35d"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1812,7 +1812,7 @@ dependencies = [
 [[package]]
 name = "lora-modulation"
 version = "0.1.5"
-source = "git+https://github.com/swaits/lora-rs.git?branch=fixed#e8a52ebd35352ce0267148fd392a0b1956d7735f"
+source = "git+https://github.com/swaits/lora-rs.git?branch=fixed#043d7659dfe2148913f16b2f7ea3e9241642b770"
 dependencies = [
  "defmt 0.3.100",
 ]
@@ -1820,7 +1820,7 @@ dependencies = [
 [[package]]
 name = "lora-phy"
 version = "3.0.2-alpha"
-source = "git+https://github.com/swaits/lora-rs.git?branch=fixed#e8a52ebd35352ce0267148fd392a0b1956d7735f"
+source = "git+https://github.com/swaits/lora-rs.git?branch=fixed#043d7659dfe2148913f16b2f7ea3e9241642b770"
 dependencies = [
  "defmt 0.3.100",
  "document-features",
@@ -1834,7 +1834,7 @@ dependencies = [
 [[package]]
 name = "lorawan"
 version = "0.9.1"
-source = "git+https://github.com/swaits/lora-rs.git?branch=fixed#e8a52ebd35352ce0267148fd392a0b1956d7735f"
+source = "git+https://github.com/swaits/lora-rs.git?branch=fixed#043d7659dfe2148913f16b2f7ea3e9241642b770"
 dependencies = [
  "aes",
  "cmac",
@@ -1846,7 +1846,7 @@ dependencies = [
 [[package]]
 name = "lorawan-device"
 version = "0.12.2"
-source = "git+https://github.com/swaits/lora-rs.git?branch=fixed#e8a52ebd35352ce0267148fd392a0b1956d7735f"
+source = "git+https://github.com/swaits/lora-rs.git?branch=fixed#043d7659dfe2148913f16b2f7ea3e9241642b770"
 dependencies = [
  "defmt 0.3.100",
  "document-features",
@@ -1861,7 +1861,7 @@ dependencies = [
 [[package]]
 name = "lorawan-macros"
 version = "0.1.0"
-source = "git+https://github.com/swaits/lora-rs.git?branch=fixed#e8a52ebd35352ce0267148fd392a0b1956d7735f"
+source = "git+https://github.com/swaits/lora-rs.git?branch=fixed#043d7659dfe2148913f16b2f7ea3e9241642b770"
 dependencies = [
  "proc-macro2",
  "quote",

Cargo.toml

@@ -3,7 +3,7 @@ members = ["."]
 
 [package]
 name = "donglora"
-version = "1.5.0"
+version = "1.5.1"
 edition = "2021"
 build = "build.rs"
 authors = ["Stephen Waits <steve@waits.net>"]
@@ -29,7 +29,7 @@ embassy-usb-driver = "0.2"
 ucobs = { version = "0.3", features = ["legacy-msrv"] }
 heapless = "0.9"
 donglora-protocol = "1"
-hsmc = { version = "0.5", default-features = false, features = ["embassy", "trace-defmt"] }
+hsmc = { version = "0.6", default-features = false, features = ["embassy", "trace-defmt"] }
 # Fork branch carrying CAD IRQ-clear / standby-after-CAD fixes awaiting upstream PRs.
 # Switch back to crates.io once changes are upstreamed.
 lora-phy = { git = "https://github.com/swaits/lora-rs.git", branch = "fixed", features = ["defmt-03"] }

src/radio.rs

@@ -1252,29 +1252,33 @@ impl RadioActions for RadioActionContext<'_> {
                     Some(lora) => reconfigure_radio(lora, &cfg).await,
                     None => Err(RadioError::Busy),
                 };
-                if recfg_result.is_err() {
-                    // Hardware failure: drop to Unconfigured (spec §6.3).
-                    // Clear all per-session state — including any in-flight
-                    // RxStart tag — so the next CmdRxStart in Unconfigured
-                    // is rejected cleanly (rather than racing a stale tag
-                    // through respond_err_start_rx on an unrelated path).
-                    self.config = None;
-                    self.cad_retry_delay_us = 0;
-                    self.pending_rx_start_tag = None;
-                    info!("config cleared (apply_set_config failure tag={=u16})", tag);
-                    self.send(tag, DeviceMessage::Err(ErrorCode::ERadio)).await;
-                    // Wedge takes precedence over ConfigFailedRadio so the
-                    // chart enters Recovering (NRESET + lora.init()) instead
-                    // of bouncing back to Unconfigured with a still-wedged
-                    // chip that the next SET_CONFIG would also fail on.
-                    if take_wedge_flag() {
-                        let _ = self.emit(RadioInput::WedgeDetected);
-                    } else {
-                        let _ = self.emit(RadioInput::ConfigFailedRadio);
+                let mdltn = match recfg_result {
+                    Ok(m) => m,
+                    Err(_) => {
+                        // Hardware failure: drop to Unconfigured (spec §6.3).
+                        // Clear all per-session state — including any in-flight
+                        // RxStart tag — so the next CmdRxStart in Unconfigured
+                        // is rejected cleanly (rather than racing a stale tag
+                        // through respond_err_start_rx on an unrelated path).
+                        self.config = None;
+                        self.cad_retry_delay_us = 0;
+                        self.pending_rx_start_tag = None;
+                        info!("config cleared (apply_set_config failure tag={=u16})", tag);
+                        self.send(tag, DeviceMessage::Err(ErrorCode::ERadio)).await;
+                        // Wedge takes precedence over ConfigFailedRadio so the
+                        // chart enters Recovering (NRESET + lora.init()) instead
+                        // of bouncing back to Unconfigured with a still-wedged
+                        // chip that the next SET_CONFIG would also fail on.
+                        if take_wedge_flag() {
+                            let _ = self.emit(RadioInput::WedgeDetected);
+                        } else {
+                            let _ = self.emit(RadioInput::ConfigFailedRadio);
+                        }
+                        return;
                     }
-                    return;
-                }
+                };
                 self.config = Some(cfg);
+                self.mdltn = Some(mdltn);
                 info!("config set (apply_set_config success tag={=u16})", tag);
                 self.cad_retry_delay_us = toa_us(&cfg, CAD_ASSUMED_PEER_PAYLOAD_B);
                 if self.cad_retry_delay_us > CAD_BUDGET_US {
@@ -2094,12 +2098,28 @@ fn to_lora_mod_params(
     lora.create_modulation_params(sf, bw, cr, cfg.freq_hz)
 }
 
-async fn reconfigure_radio(lora: &mut LoRaDriver, cfg: &LoRaConfig) -> Result<(), RadioError> {
+async fn reconfigure_radio(
+    lora: &mut LoRaDriver,
+    cfg: &LoRaConfig,
+) -> Result<lora_phy::mod_params::ModulationParams, RadioError> {
     lora_setup("reconfigure_radio.enter_standby", lora.enter_standby()).await?;
-    // Calibrate image etc. via a throwaway create_modulation_params call
-    // — inside the SET_CONFIG OK window so first TX/RX is fast.
-    let _ = to_lora_mod_params(lora, cfg)?;
-    Ok(())
+    // Apply the host-supplied LoRa sync word. The protocol field is a
+    // u16 holding the SX126x register pair in big-endian order
+    // (RadioLib convention: 0x1424 == byte 0x12 == LoRa "private" /
+    // MeshCore; 0x3444 == byte 0x34 == LoRaWAN "public"). lora-phy's
+    // set_lora_sync_word takes the underlying single-byte form, so
+    // undo the nibble encoding: convert_sync_word(byte) puts the
+    // chip's mandatory 0x4 in the low nibble of each register byte,
+    // and the high nibble of each register byte holds the original
+    // byte's high/low nibble respectively.
+    let [hi, lo] = cfg.sync_word.to_be_bytes();
+    let sync_byte = (hi & 0xF0) | (lo >> 4);
+    lora_setup(
+        "reconfigure_radio.set_lora_sync_word",
+        lora.set_lora_sync_word(sync_byte),
+    )
+    .await?;
+    to_lora_mod_params(lora, cfg)
 }
 
 fn validate_lora(cfg: &LoRaConfig, info: &Info) -> Result<(), ErrorCode> {