Release fw 0.8.5: BT1035 I2S boot init and hardware doc alignment.

Switch BT1035 bring-up from Line-In to I2S slave (AT+AUXCFG=3, AT+I2SCFG=67) to match the ADAU1701 PCM routing, confirm 2 kΩ I2C pull-ups on R1/R16, and sync firmware docs, AGENTS rules, and the DATASHEET bundle.

Co-authored-by: Cursor <cursoragent@cursor.com>

Hardware/DATASHEET/README.md

@@ -0,0 +1,22 @@
+# Component datasheets (DigiRadio hardware)
+
+Authoritative vendor PDFs used for schematic/PCB design review and firmware
+bring-up. Paths are relative to this repository root (`DigiRadio/`).
+
+| File | Component | Use in DigiRadio |
+|------|-----------|------------------|
+| `SI4684-A10.pdf` | Silicon Labs Si4684-A10 | RSTB power sequencing, SPI framing, supply levels, SMODE |
+| `adau1701.pdf` | Analog Devices ADAU1701 | I²C pull-ups (2 kΩ R1/R16 on PCB; datasheet 2.2 kΩ), MCLK = 256×fS, serial-port master/slave loopback (MP10→MP4, MP11→MP5) |
+| `AN851.pdf` | Silicon Labs AN851 | Si4684 bypass capacitors, antenna layout, schematic guidance |
+| `FSC-BT1035_Datasheet_EN.pdf` | Feasycom FSC-BT1035 | Module pinout, electrical and mechanical specs (v1.0) |
+| `FSC-BT1035_programming_user_guide_1.1.1.pdf` | Feasycom FSC-BT1035 | **AT command reference** — firmware `core::Bt1035At*` maps to §5/§6 |
+
+## Firmware cross-reference
+
+| Manual section | Primary datasheet |
+|----------------|-------------------|
+| `ch-hardware.tex` §validation | `SI4684-A10.pdf`, `AN851.pdf`, `adau1701.pdf`, BT1035 datasheets |
+| `ch-bt1035.tex` §AT commands | `FSC-BT1035_programming_user_guide_1.1.1.pdf` §5 |
+
+When extending BT1035 commands, cite the programming guide section in code comments
+and add a host test in `Software/components/core/test/bt1035_at_test.cpp`.

README.md

@@ -7,7 +7,7 @@
 **Open-source digital radio — Si4684 tuner · ADAU1701 SigmaDSP · Bluetooth aptX Adaptive · ESP32-S3**
 
 ![Status](https://img.shields.io/badge/hardware-verified-brightgreen)
-![Firmware](https://img.shields.io/badge/firmware-0.8.3-blue)
+![Firmware](https://img.shields.io/badge/firmware-0.8.5-blue)
 ![CI](https://github.com/manvalan/DigiRadio/actions/workflows/ci.yml/badge.svg)
 ![PCB](https://img.shields.io/badge/PCB-6--layer-blue)
 ![Hardware License](https://img.shields.io/badge/hardware-CERN--OHL--S-lightgrey)
@@ -57,11 +57,11 @@ no analogue conversions are introduced between the tuner and the wireless link.
 - **6-layer impedance-controlled PCB**, 50 × 90 mm, two ground planes
 - Three antennas (ESP32 2.4 GHz, BT1035 2.4 GHz, FM/DAB SMA) with proper keep-outs
 
-### Firmware (ESP-IDF, C++23 — fw **0.8.3**)
+### Firmware (ESP-IDF, C++23 — fw **0.8.5**)
 
 | Area | Capability |
 |------|------------|
-| **Boot & chips** | Si4684 DAB+FM firmware load (HOST_LOAD blobs), ADAU1701 RAM program at every boot, BT1035 UART init |
+| **Boot & chips** | Si4684 DAB+FM firmware load (HOST_LOAD blobs), ADAU1701 RAM program at every boot, BT1035 I2S slave init (`AT+AUXCFG=3`, `AT+I2SCFG=67`) |
 | **Tuner** | FM tune/seek, DAB ensemble tune, service scan & play, RSQ/RDS, DAB event status |
 | **Now playing** | FM RDS (PS, RadioText, PI, PTY) and DAB Dynamic Label (DLS) in status JSON and web UI |
 | **Audio** | 6-band EQ, input mixer, stereo/bass enhancement overlays, profile persist in encrypted NVS |
@@ -83,6 +83,8 @@ Vertical slices landed on `main` (newest first):
 
 | Version | Highlights |
 |---------|------------|
+| **0.8.5** | BT1035 I2S slave boot init (schematic-aligned); I2C pull-ups R1/R16 confirmed 2 kΩ; `Hardware/DATASHEET/` bundle |
+| **0.8.4** | Dual OTA + DSP blob updates, EEPROM identity, System tab OTA/DSP upload |
 | **0.8.3** | NVS + flash encryption (development mode), `initEncryptedStorage`, security docs |
 | **0.8.2** | Tabbed Web UI (now-playing, 6-band EQ, all REST); Si4684 blob CI policy |
 | **0.8.1** | `IntegrationService` — boot preset recall, tune orchestration (tuner + audio + NVS `last_preset`); services stub removed |
@@ -228,10 +230,10 @@ Generated C++ API reference: run `doxygen Doxyfile` → `Software/docs/api/html/
 | **PCB layout** | 6-layer, DRC clean, plane continuity verified |
 | **BOM** | Finalised (manufacturable / sourced) |
 | **Prototype** | In fabrication (PCBWay) |
-| **Firmware** | **0.8.3** on `main` — encrypted NVS, full Web UI, integration, RDS/DLS |
+| **Firmware** | **0.8.5** on `main` — BT1035 I2S boot init, dual OTA, encrypted NVS, full Web UI |
 | **Web UI** | Tabbed SPA covering every REST endpoint |
 | **HIL** | Device validation pending PCB (`Software/docs/security-flash-nvs.md`) |
-| **Agent backlog** | Feature-complete on `main` (fw 0.8.3); see [`Software/docs/TODO.md`](Software/docs/TODO.md) |
+| **Agent backlog** | Feature-complete on `main` (fw 0.8.5); see [`Software/docs/TODO.md`](Software/docs/TODO.md) |
 
 ---
 
@@ -239,9 +241,12 @@ Generated C++ API reference: run `doxygen Doxyfile` → `Software/docs/api/html/
 
 The board is manufactured with **PCBWay** as a 6-layer, impedance-controlled PCB
 with turnkey assembly. The FSC-BT1035 Bluetooth module is sourced from Feasycom
-(the footprint uses a BT806-compatible, pin-identical land pattern). See the
+(the footprint uses a BT806-compatible, pin-identical land pattern). Component
-[Technical Manual](Software/docs/manual/manual.tex) hardware chapter and manufacturing
+datasheets for design review live in
-notes for fabrication settings and MSL-3 handling of the BT module.
+[`Hardware/DATASHEET/`](Hardware/DATASHEET/) (Si4684-A10, AN851, ADAU1701, FSC-BT1035).
+See the [Technical Manual](Software/docs/manual/manual.tex) hardware chapter
+and manufacturing notes for fabrication settings and MSL-3 handling of the BT
+module.
 
 ---
 

Software/.cursor/rules/20-drivers.mdc

@@ -29,6 +29,6 @@ Full spec: @AGENTS.md §7.1–7.3.
 
 ## FSC-BT1035 (QCC3056, AT over UART)
 - Typed command builder; explicit OK/ERROR/timeout parsing.
-- AT+AUXCFG=1 (Line-In) is mandatory in the init sequence and covered by
+- AT+AUXCFG=3 and AT+I2SCFG=67 (I2S slave 48 kHz) are mandatory in the
-  a test on the command string. Unknown responses are an error, not
+  init sequence and covered by host tests. Unknown responses are an error,
-  ignored.
+  not ignored.

Software/AGENTS.md

@@ -397,9 +397,11 @@ Layered, dependencies point inward only:
 
 - Controlled by AT commands over UART. Build commands with a typed
   builder; parse responses with explicit `OK`/`ERROR`/timeout handling.
-- **Line-In mode is mandatory:** the `AT+AUXCFG=1` step must be part of
+- **I\textsuperscript{2}S slave mode is mandatory:** `AT+AUXCFG=3` and
-  the documented init sequence and covered by a test on the command
+  `AT+I2SCFG=67` (Feasycom programming guide §5.1.25 / §5.1.4) must be part
-  string. Losing it silently breaks the audio path.
+  of the documented init sequence and covered by host tests. The PCB routes
+  ADAU I\textsuperscript{2}S to the module; `AT+AUXCFG=1` (Line-In) does not
+  match the schematic.
 - The AT subset in use is enumerated and documented; unknown responses
   are an error value, not ignored.
 

Software/README.md

@@ -2,14 +2,14 @@
 
 Open-source Hi-Fi DAB+/FM receiver firmware for the ESP32-S3.
 
-**Status:** fw **0.8.4** on `main` — dual OTA + DSP blob updates, EEPROM identity,
+**Status:** fw **0.8.5** on `main` — BT1035 I2S slave boot init, dual OTA + DSP blob updates, EEPROM identity,
 NVS + flash encryption (development mode), tabbed Web UI with **System** uploads,
 **15** host tests, **4** CI jobs. Agent tasks T1–T12 complete; device HIL pending
 first PCB.
 
-| Area | Shipped in 0.8.4 |
+| Area | Shipped in 0.8.5 |
 |------|------------------|
-| Boot | Si4684 HOST_LOAD, ADAU1701 RAM program, BT1035 Line-In init |
+| Boot | Si4684 HOST_LOAD, ADAU1701 RAM program, BT1035 I2S slave init (`AUXCFG=3`, `I2SCFG=67`) |
 | Tuner | FM/DAB tune, seek up/down, RSQ, RDS, DAB services + DLS |
 | Audio | 6-band EQ, mixer, stereo/bass enhance, NVS profile |
 | Updates | ESP32 dual-OTA, ADAU1701 `dsp` partition blob replay |
@@ -85,7 +85,7 @@ Header shows EEPROM serial from `/api/health`. Source:
 `components/net/www/index.html` · regenerate embed:
 `tools/gzip-www.sh`.
 
-## HTTP API (fw 0.8.4)
+## HTTP API (fw 0.8.5)
 
 | Method | Path | Purpose |
 |--------|------|---------|

Software/components/core/include/core/Bt1035At.hpp

@@ -37,7 +37,8 @@ namespace core {
  */
 enum class Bt1035AtCommand {
     Ping,             ///< AT — link check.
-    AuxLineIn,        ///< AT+AUXCFG=1 — wired Line-In from ADAU1701 (mandatory).
+    I2sMode,          ///< AT+AUXCFG=3 — I2S input from ADAU1701 (mandatory).
+    I2sSlave48k32,    ///< AT+I2SCFG=67 — I2S slave 48 kHz 32-bit (§5.1.4).
     PairDiscoverable, ///< AT+PAIR=1 — enter BR/EDR/BLE discoverable mode.
     PairHidden,       ///< AT+PAIR=0 — leave discoverable mode.
     A2dpStat,         ///< AT+A2DPSTAT — read A2DP link state.
@@ -83,7 +84,10 @@ enum class Bt1035AtResponseKind {
 };
 
 /** Number of commands in bootInitSequence(). */
-inline constexpr std::size_t kBt1035BootInitCommandCount = 2U;
+inline constexpr std::size_t kBt1035BootInitCommandCount = 3U;
+
+/** Feasycom programming guide §5.1.4: I2S slave, 48 kHz, 32-bit. */
+inline constexpr std::uint8_t kBt1035I2sSlave48k32Param = 67U;
 
 /**
  * @brief    buildBt1035AtLine — serialise a command with CRLF terminator.
@@ -102,7 +106,7 @@ inline constexpr std::size_t kBt1035BootInitCommandCount = 2U;
  * @brief    bootInitSequence — mandatory bring-up commands in order.
  *
  * @dname    bootInitSequence
- * @return   Ping then AuxLineIn (AT+AUXCFG=1).
+ * @return   Ping, I2sMode (AUXCFG=3), I2sSlave48k32 (I2SCFG=67).
  * @pubstate none
  *
  * @author   Michele Bigi
@@ -165,6 +169,21 @@ parseBt1035A2dpStatResponse(std::string_view response);
  */
 [[nodiscard]] std::string buildBt1035SetAutoConnLine(std::uint8_t times);
 
+/**
+ * @brief    buildBt1035SetNameLine — AT+NAME with optional MAC suffix flag.
+ *
+ * @dname    buildBt1035SetNameLine
+ * @param    name  BR/EDR local name (1--31 ASCII bytes per Feasycom §5.1.16).
+ * @param    enableMacSuffix  false sends Param2=0 (disable module suffix).
+ * @return   Full AT line including CRLF.
+ * @pubstate none
+ *
+ * @author   Michele Bigi
+ * @date     2026-07-08
+ */
+[[nodiscard]] std::string buildBt1035SetNameLine(std::string_view name,
+                                                 bool enableMacSuffix = false);
+
 /**
  * @brief    parseBt1035NameResponse — extract +NAME= value.
  *

Software/components/core/include/core/CompanionChipStatus.hpp

@@ -27,7 +27,7 @@ namespace core {
 struct CompanionChipStatus {
     bool si4684Ready;   ///< Si4684 HOST_LOAD completed.
     bool adau1701Ready; ///< ADAU1701 SigmaStudio download completed.
-    bool bt1035Ready;   ///< BT1035 Line-In init (AT+AUXCFG=1) completed.
+    bool bt1035Ready;   ///< BT1035 I2S init (AUXCFG=3 + I2SCFG=67) completed.
 };
 
 } // namespace core

Software/components/core/src/Bt1035At.cpp

@@ -101,8 +101,10 @@ std::string buildBt1035AtLine(Bt1035AtCommand command)
     switch (command) {
     case Bt1035AtCommand::Ping:
         return "AT\r\n";
-    case Bt1035AtCommand::AuxLineIn:
+    case Bt1035AtCommand::I2sMode:
-        return "AT+AUXCFG=1\r\n";
+        return "AT+AUXCFG=3\r\n";
+    case Bt1035AtCommand::I2sSlave48k32:
+        return "AT+I2SCFG=67\r\n";
     case Bt1035AtCommand::PairDiscoverable:
         return "AT+PAIR=1\r\n";
     case Bt1035AtCommand::PairHidden:
@@ -129,11 +131,21 @@ std::string buildBt1035SetAutoConnLine(std::uint8_t times)
     return "AT+AUTOCONN=" + std::to_string(times) + "\r\n";
 }
 
+std::string buildBt1035SetNameLine(std::string_view name, bool enableMacSuffix)
+{
+    if (name.empty() || name.size() > 31U) {
+        return {};
+    }
+    return std::string("AT+NAME=") + std::string(name) + ","
+           + (enableMacSuffix ? "1" : "0") + "\r\n";
+}
+
 std::array<Bt1035AtCommand, kBt1035BootInitCommandCount> bootInitSequence() noexcept
 {
     return std::array<Bt1035AtCommand, kBt1035BootInitCommandCount>{
         Bt1035AtCommand::Ping,
-        Bt1035AtCommand::AuxLineIn,
+        Bt1035AtCommand::I2sMode,
+        Bt1035AtCommand::I2sSlave48k32,
     };
 }
 

Software/components/core/test/bt1035_at_test.cpp

@@ -28,13 +28,24 @@ namespace {
         std::cerr << "init sequence size mismatch\n";
         return EXIT_FAILURE;
     }
-    if (sequence[1U] != core::Bt1035AtCommand::AuxLineIn) {
+    if (sequence[1U] != core::Bt1035AtCommand::I2sMode) {
-        std::cerr << "AUXCFG=1 must be in init sequence\n";
+        std::cerr << "I2S mode must be in init sequence\n";
         return EXIT_FAILURE;
     }
-    const std::string aux = core::buildBt1035AtLine(core::Bt1035AtCommand::AuxLineIn);
+    if (sequence[2U] != core::Bt1035AtCommand::I2sSlave48k32) {
-    if (aux != "AT+AUXCFG=1\r\n") {
+        std::cerr << "I2SCFG must be in init sequence\n";
-        std::cerr << "AUXCFG command line mismatch\n";
+        return EXIT_FAILURE;
+    }
+    const std::string i2sMode =
+        core::buildBt1035AtLine(core::Bt1035AtCommand::I2sMode);
+    if (i2sMode != "AT+AUXCFG=3\r\n") {
+        std::cerr << "AUXCFG=3 command line mismatch\n";
+        return EXIT_FAILURE;
+    }
+    const std::string i2sCfg =
+        core::buildBt1035AtLine(core::Bt1035AtCommand::I2sSlave48k32);
+    if (i2sCfg != "AT+I2SCFG=67\r\n") {
+        std::cerr << "I2SCFG=67 command line mismatch\n";
         return EXIT_FAILURE;
     }
     return EXIT_SUCCESS;
@@ -117,6 +128,11 @@ namespace {
         std::cerr << "AUTOCONN command line mismatch\n";
         return EXIT_FAILURE;
     }
+    if (core::buildBt1035SetNameLine("DigiRadio-A1B2", false)
+        != "AT+NAME=DigiRadio-A1B2,0\r\n") {
+        std::cerr << "NAME set command line mismatch\n";
+        return EXIT_FAILURE;
+    }
     return EXIT_SUCCESS;
 }
 

Software/components/drivers/bt1035/include/bt1035/Bt1035Driver.hpp

@@ -48,7 +48,7 @@ struct Bt1035Pins {
  * @dname    Bt1035Driver
  * @return   n/a (type)
  * @pubstate Owns UART port after boot(). booted_ true after init sequence
- *           including AT+AUXCFG=1 (Line-In from ADAU1701).
+ *           including AT+AUXCFG=3 and AT+I2SCFG=67 (I2S slave from ADAU1701).
  *
  * @author   Michele Bigi
  * @date     2026-07-06
@@ -86,7 +86,7 @@ public:
      *
      * @dname    boot
      * @return   Ok on success, or Bt1035Error.
-     * @pubstate sets booted_ after Ping + AT+AUXCFG=1 both return OK.
+     * @pubstate sets booted_ after Ping + I2S init both return OK.
      *
      * Sequence: hardware reset, UART @ 115200 with RTS/CTS, then
      * core::bootInitSequence() (see manual chapter bt1035).
@@ -97,7 +97,7 @@ public:
     [[nodiscard]] std::expected<void, Bt1035Error> boot();
 
     /**
-     * @brief    isBooted — query whether Line-In init succeeded.
+     * @brief    isBooted — query whether I2S init succeeded.
      *
      * @dname    isBooted
      * @return   true after successful boot().
@@ -177,7 +177,7 @@ public:
      * @dname    setDeviceName
      * @param    name  Bluetooth name (Feasycom FSC-BT1035 AT+NAME command).
      * @return   Ok on success, or Bt1035Error.
-     * @pubstate sends AT+NAME after boot; does not alter AT+AUXCFG=1 init.
+     * @pubstate sends AT+NAME after boot; does not alter I2S init sequence.
      *
      * @author   Michele Bigi
      * @date     2026-07-07

Software/components/drivers/bt1035/src/Bt1035Driver.cpp

@@ -169,10 +169,14 @@ std::expected<void, Bt1035Error> Bt1035Driver::setDeviceName(
     if (auto ready = ensureBooted(); !ready) {
         return ready;
     }
-    if (name.empty() || name.size() > 32U) {
+    if (name.empty() || name.size() > 31U) {
+        return std::unexpected(Bt1035Error::UnexpectedResponse);
+    }
+    const std::string line =
+        core::buildBt1035SetNameLine(name, false);
+    if (line.empty()) {
         return std::unexpected(Bt1035Error::UnexpectedResponse);
     }
-    std::string line = std::string("AT+NAME=") + std::string(name) + "\r\n";
     return transmitAndExpectOk(line);
 }
 
@@ -315,7 +319,7 @@ std::expected<void, Bt1035Error> Bt1035Driver::boot()
     }
 
     booted_ = true;
-    ESP_LOGI(kTag, "Line-In mode enabled (AT+AUXCFG=1)");
+    ESP_LOGI(kTag, "I2S slave mode enabled (AT+AUXCFG=3, AT+I2SCFG=67)");
     return {};
 }
 

Software/components/net/src/SetupWebServer.cpp

@@ -60,7 +60,7 @@ namespace net {
 
 namespace {
 constexpr char kTag[] = "SetupWebServer";
-constexpr char kFirmwareVersion[] = "0.8.4";
+constexpr char kFirmwareVersion[] = "0.8.5";
 constexpr unsigned kRebootDelaySec = 3;
 
 extern const uint8_t www_index_html_gz_start[] asm(

Software/docs/TODO.md

@@ -3,7 +3,7 @@
 Agent task list and hardware-in-the-loop backlog. Working directory for all
 commands is `Software/`.
 
-**Current firmware:** `0.8.4` — dual OTA + DSP blob updates, EEPROM identity,
+**Current firmware:** `0.8.5` — BT1035 I2S slave boot init, dual OTA + DSP blob updates, EEPROM identity,
 NVS + flash encryption (dev mode), tabbed Web UI with System uploads, CI gate
 (4 jobs).
 
@@ -14,7 +14,7 @@ NVS + flash encryption (dev mode), tabbed Web UI with System uploads, CI gate
 
 ---
 
-## Completed agent tasks (T1–T12, fw 0.7.1–0.8.4)
+## Completed agent tasks (T1–T12, fw 0.7.1–0.8.5)
 
 | Task | Version | Summary |
 |------|---------|---------|
@@ -31,6 +31,10 @@ NVS + flash encryption (dev mode), tabbed Web UI with System uploads, CI gate
 | **T11** | 0.8.4 | Updatable ADAU1701 program — `POST /api/dsp/program`, DRAD blob |
 | **T12** | 0.8.4 | ESP32 OTA — `POST /api/system/ota`, rollback confirm on boot |
 
+**0.8.5** (hardware/doc alignment): BT1035 boot uses `AT+AUXCFG=3` +
+`AT+I2SCFG=67` (I2S from ADAU1701, not Line-In); I2C pull-ups R1/R16
+confirmed 2\,kΩ; `Hardware/DATASHEET/` bundle + manual cross-refs.
+
 Also landed (not numbered): BT1035 pairing (`BluetoothService`), station presets
 (fw 0.7.0), companion-chip boot (Slice 3), ADAU1701 runtime (Slice 5).
 
@@ -62,13 +66,14 @@ a sacrificial unit; confirm RELEASE mode policy before shipping.
 
 ## Open firmware polish (non-blocking)
 
-Done in fw 0.8.4 unless noted:
+Done in fw 0.8.5 unless noted:
 
-- FM seek down — `POST /api/tuner/seek` with `{"direction":"down"}`.
+- BT1035 boot — I2S slave init (`AT+AUXCFG=3`, `AT+I2SCFG=67`) per PCB routing (0.8.5).
+- FM seek down — `POST /api/tuner/seek` with `{"direction":"down"}` (0.8.4).
 - BT1035 — query/set name, paired list (`AT+PLIST`), auto-reconnect
-  (`AT+AUTOCONN`) per Feasycom BT1035 manual.
+  (`AT+AUTOCONN`) per Feasycom BT1035 manual (0.8.4).
 - Si4684 — `STOP_DIGITAL_SERVICE` (0x82) before FM band switch when DAB
-  audio is active; ensemble metrics remain via `DAB_DIGRAD_STATUS` in status.
+  audio is active; ensemble metrics remain via `DAB_DIGRAD_STATUS` in status (0.8.4).
 
 ---
 

Software/docs/manual/ch-api.tex

@@ -6,7 +6,7 @@ implemented in \texttt{SetupWebServer}. Request bodies are parsed into
 domain types in the pure core (\texttt{components/core}) before any
 persistence or driver call. Exact C++ signatures live in the generated
 Doxygen output under \texttt{docs/api/}; this chapter documents the
-wire protocol and behaviour as shipped in firmware~0.8.4.
+wire protocol and behaviour as shipped in firmware~0.8.5.
 
 \section{Transport and reachability}
 
@@ -36,7 +36,7 @@ Returns a health-check DTO serialised by
 
 \begin{drnote}[Response schema]
 \begin{drcode}[JSON]
-{"status":"ok","fw":"0.8.4","serialNumber":"0004A3123456",
+{"status":"ok","fw":"0.8.5","serialNumber":"0004A3123456",
  "chips":{"si4684":true,"adau1701":true,"bt1035":true}}
 \end{drcode}
 \begin{itemize}

Software/docs/manual/ch-bt1035.tex

@@ -9,8 +9,8 @@ The Feasycom FSC-BT1035 (Qualcomm QCC3056) is the wireless output stage of
 DigiRadio: it receives PCM from the ADAU1701 over I\textsuperscript{2}S and
 streams Bluetooth audio with aptX, aptX~HD, and aptX~Adaptive. This chapter
 documents how the ESP32-S3 controls the module over UART (AT commands with
-RTS/CTS), why Line-In mode is mandatory, and how \texttt{bt1035::Bt1035Driver}
+RTS/CTS), why I\textsuperscript{2}S slave mode is mandatory, and how
-implements the bring-up sequence.
+\texttt{bt1035::Bt1035Driver} implements the bring-up sequence.
 
 \begin{drref}[Hardware context]
 Board wiring (UART pins, I\textsuperscript{2}S to the module, flow control)
@@ -29,9 +29,10 @@ samples for Bluetooth; it only configures the module so the wired path is
 accepted and encoded for transmission.
 
 Without firmware init the module may stay in a default mode that ignores the
-Line-In from the DSP. The mandatory \texttt{AT+AUXCFG=1} command selects
+I\textsuperscript{2}S bus from the ADAU1701. The mandatory
-auxiliary/Line-In input --- omitting it silently breaks the entire wireless
+\texttt{AT+AUXCFG=3} and \texttt{AT+I2SCFG=67} commands select I\textsuperscript{2}S
-output (Section~\ref{sec:bt1035-linein}).
+slave input at 48\,kHz --- omitting them silently breaks the entire wireless
+output (Section~\ref{sec:bt1035-i2s}).
 
 \section{Control interface}
 \label{sec:bt1035-uart}
@@ -67,17 +68,19 @@ Every command expects a module reply containing \texttt{OK} or
 \end{itemize}
 
 Host tests in \texttt{components/core/test/bt1035\_at\_test.cpp} lock the
-init sequence (including \texttt{AT+AUXCFG=1}) and the parser.
+init sequence (\texttt{AT+AUXCFG=3}, \texttt{AT+I2SCFG=67}) and the parser.
 
-\section{Mandatory Line-In mode}
+\section{Mandatory I\textsuperscript{2}S slave mode}
-\label{sec:bt1035-linein}
+\label{sec:bt1035-i2s}
 
-\begin{drcaution}[AT+AUXCFG=1 is not optional]
+\begin{drcaution}[I\textsuperscript{2}S init is not optional]
-The documented init sequence must include \texttt{AT+AUXCFG=1} after a
+The board routes ADAU1701 \texttt{SDATA\_OUT0} (MP6) to the module PCM input
-successful \texttt{AT} ping. This tells the QCC3056 firmware to take audio
+with shared BCLK/LRCLK (see Chapter~\ref{ch:hardware}). The init sequence
-from the wired I\textsuperscript{2}S/Line-In port (the ADAU1701 output)
+must therefore use \texttt{AT+AUXCFG=3} (I\textsuperscript{2}S mode per
-rather than an internal source. AGENTS.md and the hardware manual both treat
+programming guide §5.1.25) followed by \texttt{AT+I2SCFG=67} (I\textsuperscript{2}S
-skipping this step as a production bug.
+slave, 48\,kHz, 32-bit per §5.1.4). \texttt{AT+AUXCFG=1} (Line-In) does
+\textbf{not} match the schematic. AGENTS.md treats skipping I\textsuperscript{2}S
+init as a production bug.
 \end{drcaution}
 
 \section{Boot sequence}
@@ -85,7 +88,7 @@ skipping this step as a production bug.
 
 At power-up \texttt{HardwareBootstrap::boot()} runs the Si4684 and ADAU1701
 first, applies the saved audio profile, then initialises the BT1035 so the
-Line-In path is ready before Wi-Fi starts.
+I\textsuperscript{2}S path is ready before Wi-Fi starts.
 
 \begin{figure}[htbp]
   \centering
@@ -99,10 +102,12 @@ Line-In path is ready before Wi-Fi starts.
     \node[drstep, fill=black!8, below=of uart] (at)
       {Send \texttt{AT} --- expect OK};
     \node[drstep, fill=black!10, below=of at] (aux)
-      {Send \texttt{AT+AUXCFG=1} --- expect OK (Line-In)};
+      {Send \texttt{AT+AUXCFG=3} --- expect OK (I\textsuperscript{2}S)};
-    \node[drstep, fill=black!6, below=of aux] (done)
+    \node[drstep, fill=black!10, below=of aux] (i2s)
+      {Send \texttt{AT+I2SCFG=67} --- expect OK (slave 48\,kHz)};
+    \node[drstep, fill=black!6, below=of i2s] (done)
       {\texttt{Bt1035Driver::isBooted()} = true};
-    \foreach \a/\b in {sys/uart, uart/at, at/aux, aux/done} {
+    \foreach \a/\b in {sys/uart, uart/at, at/aux, aux/i2s, i2s/done} {
       \draw[->] (\a) -- (\b);
     }
   \end{tikzpicture}
@@ -112,7 +117,7 @@ Line-In path is ready before Wi-Fi starts.
 
 Pairing, codec selection, and volume over Bluetooth are handled by the
 module's own firmware and NVS; DigiRadio firmware currently implements
-only the Line-In bring-up required for the wired audio path.
+only the I\textsuperscript{2}S bring-up required for the wired audio path.
 
 \section{Software architecture}
 \label{sec:bt1035-stack}
@@ -139,30 +144,38 @@ only the Line-In bring-up required for the wired audio path.
 \section{Supported AT command subset}
 \label{sec:bt1035-at}
 
-The firmware enumerates every command it sends. Extending the subset requires
+The firmware enumerates every command it sends. Wire formats follow
-updating \texttt{core::Bt1035AtCommand}, the manual, and a host test.
+\texttt{Hardware/DATASHEET/FSC-BT1035\_programming\_user\_guide\_1.1.1.pdf}
+(§5 commands, §6 events). Extending the subset requires updating
+\texttt{core::Bt1035AtCommand}, the manual, and a host test.
 
 \begin{table}[htbp]
   \centering
-  \begin{tabular}{@{}lll@{}}
+  \small
-    \drhead Enum & Line sent & Purpose \\
+  \begin{tabular}{@{}llp{5.2cm}@{}}
+    \drhead Enum & Line sent & Programming guide \\
     \midrule
-    \texttt{Ping}      & \texttt{AT}           & Verify UART link \\
+    \texttt{Ping}           & \texttt{AT}              & link check \\
-    \texttt{AuxLineIn}   & \texttt{AT+AUXCFG=1}  & Enable Line-In from ADAU \\
+    \texttt{I2sMode}        & \texttt{AT+AUXCFG=3}     & §5.1.25 Param=3 I2S \\
-    \texttt{PairDiscoverable} & \texttt{AT+PAIR=1} & Enter discoverable mode \\
+    \texttt{I2sSlave48k32}  & \texttt{AT+I2SCFG=67}    & §5.1.4 slave 48\,kHz 32-bit \\
-    \texttt{PairHidden}       & \texttt{AT+PAIR=0} & Leave discoverable mode \\
+    \texttt{PairDiscoverable} & \texttt{AT+PAIR=1} & §5.1.20 enter discoverable \\
-    \texttt{A2dpStat}         & \texttt{AT+A2DPSTAT} & Read link state \\
+    \texttt{PairHidden}       & \texttt{AT+PAIR=0} & §5.1.20 leave discoverable \\
-    \texttt{A2dpDisconnect}   & \texttt{AT+A2DPDISC} & Release A2DP session \\
+    \texttt{A2dpStat}         & \texttt{AT+A2DPSTAT} & §5.3.1; states 1--5 \\
-    \texttt{QueryName}        & \texttt{AT+NAME}     & Read module friendly name \\
+    \texttt{A2dpDisconnect}   & \texttt{AT+A2DPDISC} & §5.3.3 \\
-    \texttt{QueryAutoConn}    & \texttt{AT+AUTOCONN} & Read auto-reconnect count \\
+    \texttt{QueryName}        & \texttt{AT+NAME}     & §5.1.16 read \texttt{+NAME=} \\
-    \texttt{QueryPairedList}  & \texttt{AT+PLIST}    & List paired remotes \\
+    \texttt{QueryAutoConn}    & \texttt{AT+AUTOCONN} & §5.1.11 read \texttt{+AUTOCONN=} \\
+    \texttt{QueryPairedList}  & \texttt{AT+PLIST}    & §5.1.22; ends with \texttt{+PLIST=E} \\
     \bottomrule
   \end{tabular}
   \caption{Enumerated AT commands (\texttt{core::Bt1035AtCommand}). Boot
-    uses Ping + AuxLineIn only; pairing commands are runtime.}
+    uses Ping + I2sMode + I2sSlave48k32; pairing commands are runtime.}
   \label{tab:bt1035-at}
 \end{table}
 
+Boot also calls \texttt{AT+NAME=<identity>,0} and \texttt{AT+AUTOCONN=3}
+from \texttt{hardware\_bootstrap.cpp} (§5.1.16 suffix disabled, §5.1.11
+reconnect count).
+
 \section{Bt1035Driver API}
 \label{sec:bt1035-driver}
 
@@ -176,7 +189,7 @@ updating \texttt{core::Bt1035AtCommand}, the manual, and a host test.
     \textbf{Method} & \textbf{Purpose} \\
     \midrule
     \texttt{boot()} & Reset, UART init, run \texttt{bootInitSequence()} \\
-    \texttt{isBooted()} & \texttt{true} after Line-In init succeeded \\
+    \texttt{isBooted()} & \texttt{true} after I\textsuperscript{2}S init succeeded \\
     \texttt{sendCommand(cmd)} & Send one typed command, expect OK \\
     \texttt{enterPairingMode()} & \texttt{AT+PAIR=1} \\
     \texttt{leavePairingMode()} & \texttt{AT+PAIR=0} \\
@@ -226,19 +239,22 @@ Boot order:
   \item Si4684 \texttt{boot(Dab)} --- tuner image in RAM.
   \item ADAU1701 \texttt{boot()} --- SigmaStudio program in RAM.
   \item \texttt{AudioService::loadAndApply()} --- user mixer/EQ profile.
-  \item BT1035 \texttt{boot()} --- Line-In enabled for wireless output.
+  \item BT1035 \texttt{boot()} --- I\textsuperscript{2}S slave enabled for wireless output.
 \end{enumerate}
 
 \section{Typical usage (firmware developer)}
 \label{sec:bt1035-usage}
 
 After a successful \texttt{HardwareBootstrap::boot()}, the module is ready;
-no further calls are required for basic listening. To re-send Line-In config
+no further calls are required for basic listening. To re-send I\textsuperscript{2}S config
 after a module reset:
 
 \begin{verbatim}
 bt1035::Bt1035Driver& bt = ...;
-if (auto r = bt.sendCommand(core::Bt1035AtCommand::AuxLineIn); !r) {
+if (auto r = bt.sendCommand(core::Bt1035AtCommand::I2sMode); !r) {
+  // handle Bt1035Error
+}
+if (auto r = bt.sendCommand(core::Bt1035AtCommand::I2sSlave48k32); !r) {
   // handle Bt1035Error
 }
 \end{verbatim}
@@ -247,9 +263,12 @@ if (auto r = bt.sendCommand(core::Bt1035AtCommand::AuxLineIn); !r) {
 \label{sec:bt1035-reading}
 
 \begin{itemize}
-  \item Feasycom FSC-BT1035 AT command manual (vendor) --- full command set;
+  \item \texttt{Hardware/DATASHEET/FSC-BT1035\_programming\_user\_guide\_1.1.1.pdf}
-        firmware wraps name, paired list, and auto-reconnect for the Web UI.
+        --- authoritative AT command and event reference (§5--§6).
+  \item \texttt{Hardware/DATASHEET/FSC-BT1035\_Datasheet\_EN.pdf} --- module
+        electrical and pinout specification.
   \item Chapter~\ref{ch:hardware} --- pin map and I\textsuperscript{2}S routing.
   \item Chapter~\ref{ch:adau1701} --- DSP output that feeds the module.
-  \item \texttt{components/core/test/bt1035\_at\_test.cpp} --- init sequence test.
+  \item \texttt{components/core/test/bt1035\_at\_test.cpp} --- init sequence
+        and parser host tests.
 \end{itemize}

Software/docs/manual/ch-classes.tex

@@ -16,7 +16,7 @@ added in the same change that introduces the class. A tooling check keeps
 this chapter in step with the code, so it is always current.
 \end{drnote}
 
-The class reference tracks firmware~0.8.4 on \texttt{main}. Public classes
+The class reference tracks firmware~0.8.5 on \texttt{main}. Public classes
 are grouped by layer: domain core, application services, and hardware drivers.
 
 % ------------------------------------------------------------------
@@ -163,7 +163,8 @@ index (1--8), 12-digit MAC, and optional friendly name. Parsed by
 \section{Bt1035Driver}\label{cls:Bt1035Driver}
 UART driver for the FSC-BT1035 (Chapter~\ref{ch:bt1035}). \texttt{boot()}
 pulses RESET\#, opens UART2 with RTS/CTS, and runs
-\texttt{core::bootInitSequence()} (Ping + \texttt{AT+AUXCFG=1}). Returns
+\texttt{core::bootInitSequence()} (Ping + \texttt{AT+AUXCFG=3} +
+\texttt{AT+I2SCFG=67}). Returns
 \texttt{Bt1035Error} on timeout, ERROR response, or UART failure.
 
 \section{Adau1701Driver}\label{cls:Adau1701Driver}

Software/docs/manual/ch-firmware.tex

@@ -150,9 +150,10 @@ safeload registers.
 
 \paragraph{FSC-BT1035 (Bluetooth).}
 The module is controlled by AT commands over UART with hardware flow control.
-The initialisation sequence includes enabling Line-In mode
+The initialisation sequence includes enabling I\textsuperscript{2}S slave mode
-(\texttt{AT+AUXCFG=1}), which is required for the wired audio path from the
+(\texttt{AT+AUXCFG=3} and \texttt{AT+I2SCFG=67}), which is required for the
-DSP; command responses are parsed explicitly, with timeouts treated as errors.
+wired digital audio path from the ADAU1701 to the module.
+Command responses are parsed explicitly, with timeouts treated as errors.
 Full driver API, boot flow, and error codes are in Chapter~\ref{ch:bt1035}.
 
 \section{Configuration, storage, and user interface}
@@ -216,7 +217,8 @@ bring-up:
     restores the saved \texttt{core::AudioProfile} from NVS (or factory
     defaults) via ADAU1701 safeload before network bring-up.
   \item \textbf{FSC-BT1035} (UART): \texttt{bt1035::Bt1035Driver::boot()}
-    enables Line-In (\texttt{AT+AUXCFG=1}) after the DSP path is configured
+    enables I\textsuperscript{2}S slave mode (\texttt{AT+AUXCFG=3},
+    \texttt{AT+I2SCFG=67}) after the DSP path is configured
     (Chapter~\ref{ch:bt1035}).
 \end{enumerate}
 

Software/docs/manual/ch-hardware.tex

@@ -128,11 +128,11 @@ control (RTS/CTS). The host sends commands and parses the module's
 responses explicitly, treating timeouts as errors. Some settings are held
 in the module's own non-volatile memory.
 
-\begin{drcaution}[Line-In mode]
+\begin{drcaution}[I\textsuperscript{2}S slave mode]
-The initialisation sequence must enable Line-In mode (\texttt{AT+AUXCFG=1})
+The PCB routes ADAU1701 \texttt{SDATA\_OUT0} to the module over
-so the module accepts the wired audio coming from the DSP. Omitting it
+I\textsuperscript{2}S (BCLK, LRCLK, PCM data). Firmware must initialise
-silently breaks the audio path. Driver boot flow and AT subset are documented
+\texttt{AT+AUXCFG=3} and \texttt{AT+I2SCFG=67}, not Line-In
-in Chapter~\ref{ch:bt1035}.
+(\texttt{AT+AUXCFG=1}). See Chapter~\ref{ch:bt1035}, Section~\ref{sec:bt1035-i2s}.
 \end{drcaution}
 
 \section{The host: ESP32-S3}
@@ -379,16 +379,19 @@ satisfying the +10\,\textmu s requirement in practice.
     INTB                   & interrupt line, external pull-up (GPIO39)      & verified \\
     \bottomrule
   \end{tabular}
-  \caption{Si4684 design checks. References: Si4684-A10 datasheet
+  \caption{Si4684 design checks. References:
-    (power sequencing, SPI, supply levels) and AN851 (bypass and layout).}
+    \texttt{Hardware/DATASHEET/SI4684-A10.pdf} (power sequencing, SPI,
+    supply levels) and \texttt{Hardware/DATASHEET/AN851.pdf} (bypass and layout).}
   \label{tab:hw-val-si4684}
 \end{table}
 
 \begin{drref}[Datasheet]
-Power sequencing and SPI framing: Si4684-A10 data sheet. The user must not
+Power sequencing and SPI framing:
-pulse SSB high between bytes; SSB frames the whole command/reply.
+\texttt{Hardware/DATASHEET/SI4684-A10.pdf}. The user must not pulse SSB high
-Bypass-capacitor values and placement: AN851, \emph{Si468x Schematic and
+between bytes; SSB frames the whole command/reply.
-Layout Guide}. Boot and command protocol: AN649.
+Bypass-capacitor values and placement: \texttt{Hardware/DATASHEET/AN851.pdf},
+\emph{Si468x Schematic and Layout Guide}. Boot and command protocol: AN649.
+Local copies: \texttt{Hardware/DATASHEET/} (see \texttt{README.md}).
 \end{drref}
 
 The core, memory, and analogue rails run at 1.8\,V; only VIO is at 3.3\,V
@@ -419,7 +422,7 @@ locks up when input data arrives.
     Output master     & serial output port in Master Mode                   & verified \\
     MCLK ratio        & exactly 256\,$\times$\,f\textsubscript{S}           & verified \\
     MCLK value        & 12.288\,MHz oscillator (256\,$\times$\,48\,kHz)      & verified \\
-    I\textsuperscript{2}C pull-ups & 2.2\,k\(\Omega\) on SDA and SCL          & to verify \\
+    I\textsuperscript{2}C pull-ups & 2\,k\(\Omega\) on SDA/SCL (R16/R1)     & verified \\
     I\textsuperscript{2}C address  & 0x34 (ADDR0 = ADDR1 = GND)               & verified \\
     Self-boot         & disabled (host RAM load)                            & verified \\
     \bottomrule
@@ -430,17 +433,18 @@ locks up when input data arrives.
 \end{table}
 
 \begin{drref}[Datasheet]
-Master-clock loopback and serial-port modes: ADAU1701 data sheet, Rev.~C,
+Master-clock loopback and serial-port modes:
-Table~63 and the serial-port section. The master clock must be exactly
+\texttt{Hardware/DATASHEET/adau1701.pdf}, Rev.~C, Table~63 and the serial-port
-256\,$\times$\,f\textsubscript{S}. I\textsuperscript{2}C lines require
+section. The master clock must be exactly 256\,$\times$\,f\textsubscript{S}.
-2.2\,k\(\Omega\) pull-ups.
+I\textsuperscript{2}C lines require pull-up resistors on SDA and SCL.
+DigiRadio uses \textbf{2\,k\(\Omega\)} (schematic R1/R16; ADAU1701 datasheet
+recommends 2.2\,k\(\Omega\) --- acceptable at 3.3\,V).
 \end{drref}
 
-\begin{drcaution}[Open item --- I\textsuperscript{2}C pull-ups]
+\begin{drnote}[I\textsuperscript{2}C pull-ups confirmed]
-The ADAU1701 datasheet requires 2.2\,k\(\Omega\) pull-up resistors on SDA
+Schematic \texttt{DigitalRadio.pdf} and BOM list R1 (SCL) and R16 (SDA) as
-and SCL. Confirm these are present on the board (shared bus with the
+2\,k\(\Omega\) to 3V3 on the shared ADAU1701/EEPROM bus.
-EEPROM); this is the one ADAU check still to close.
+\end{drnote}
-\end{drcaution}
 
 \subsection{FSC-BT1035 (QCC3056)}
 \label{sec:hw-val-bt1035}
@@ -452,17 +456,24 @@ EEPROM); this is the one ADAU check still to close.
     \drhead Check & Requirement & Status \\
     \midrule
     UART with flow control & TX/RX + RTS/CTS wired            & verified \\
-    Line-In enable (firmware) & \texttt{AT+AUXCFG=1} in init   & driver rule \\
+    I\textsuperscript{2}S init (firmware) & \texttt{AT+AUXCFG=3}, \texttt{AT+I2SCFG=67} & driver rule \\
     I\textsuperscript{2}S input & receives clocks from ADAU master (slave) & verified \\
     Reset line             & RESET (GPIO17) driven by ESP32    & verified \\
     \bottomrule
   \end{tabular}
-  \caption{FSC-BT1035 design checks. The module is an I\textsuperscript{2}S
+  \caption{FSC-BT1035 design checks. Datasheet:
-    slave fed by the ADAU master; audio arrives on its I\textsuperscript{2}S
+    \texttt{Hardware/DATASHEET/FSC-BT1035\_Datasheet\_EN.pdf}; AT commands:
-    input pins.}
+    \texttt{FSC-BT1035\_programming\_user\_guide\_1.1.1.pdf} §5.}
   \label{tab:hw-val-bt1035}
 \end{table}
 
+\begin{drref}[Programming guide defaults]
+Module defaults (Feasycom release 1.1.1): BR/EDR name \texttt{FSC-BT1035},
+UART 115200/8/N/1, SSP on, auto-reconnect configurable via
+\texttt{AT+AUTOCONN=0..15}. DigiRadio overrides the name from EEPROM identity
+(\texttt{AT+NAME=<name>,0} disables the module MAC suffix).
+\end{drref}
+
 \subsection{System-level summary}
 \label{sec:hw-val-summary}
 
@@ -474,7 +485,7 @@ EEPROM); this is the one ADAU check still to close.
     Si4684 & RSTB pull-down, 1.8\,V rails, bypass caps, SPI & verified \\
     Si4684 & RSTB release only in \texttt{Si4684Driver::boot()} & verified \\
     ADAU1701 & clock loopback, master mode, 256$\times$f\textsubscript{S} & verified \\
-    ADAU1701 & I\textsuperscript{2}C 2.2\,k\(\Omega\) pull-ups & to verify \\
+    ADAU1701 & I\textsuperscript{2}C 2\,k\(\Omega\) pull-ups (R1/R16) & verified \\
     FSC-BT1035 & UART + flow control, I\textsuperscript{2}S slave & verified \\
     Clocking & single 48\,kHz domain, ADAU master & verified \\
     \bottomrule
@@ -483,6 +494,6 @@ EEPROM); this is the one ADAU check still to close.
   \label{tab:hw-val-summary}
 \end{table}
 
-The only open hardware check is the presence of the 2.2\,k\(\Omega\)
+The consolidated pre-fabrication validation is complete for all
-I\textsuperscript{2}C pull-ups on the ADAU/EEPROM bus. All damage-class
+damage-class items (Si4684 power sequencing and supply levels) and the
-items (Si4684 power sequencing and supply levels) are verified.
+shared I\textsuperscript{2}C bus.

Software/docs/manual/ch-intro.tex

@@ -4,7 +4,7 @@
 DigiRadio is an open-source, high-fidelity digital radio receiver. It
 receives DAB+ and FM broadcasts, processes the audio through a dedicated
 signal processor, and streams the result over Bluetooth using a
-high-resolution codec. Firmware~0.8.4 on \texttt{main} provides encrypted
+high-resolution codec. Firmware~0.8.5 on \texttt{main} provides encrypted
 storage, a tabbed configuration web UI, and the full REST API documented
 in Chapter~\ref{ch:api}. The whole project --- hardware and firmware --- is
 released as open source for the maker and audio community to study,

Software/docs/manual/manual.tex

@@ -30,7 +30,7 @@
 \vfill
 {\color{drInk}\large Michele Bigi\par}
 \vspace{2mm}
-{\color{drGray}Firmware 0.8.4 \quad\textbullet\quad 2026\par}
+{\color{drGray}Firmware 0.8.5 \quad\textbullet\quad 2026\par}
 \vspace{2mm}
 {\color{drGray}Hardware: CERN-OHL-S v2 \quad\textbullet\quad Firmware: Apache-2.0\par}
 \vspace{2mm}

Software/instructions.md

@@ -4,7 +4,7 @@ Read this together with `AGENTS.md` and everything under
 `.cursor/rules/`. Those define *how* to write code; this file defines
 *what we are building* and the current state on `main`.
 
-**Firmware on `main`:** **0.8.4** — agent tasks T1–T12 complete; device HIL
+**Firmware on `main`:** **0.8.5** — agent tasks T1–T12 complete; device HIL
 pending PCB arrival.
 
 ## What DigiRadio is
@@ -66,7 +66,8 @@ unless the user requests them.
 
 - ESP-IDF `esp32s3`, C++23, `components/core` host-testable.
 - SoftAP `DigiRadio-<suffix>` (or setup fallback), gzipped page, `GET /api/health`.
-- Health JSON includes `fw` (today **0.8.4**), `serialNumber`, companion-chip flags.
+- Health JSON includes `fw` (today **0.8.5**), `serialNumber`, companion-chip flags.
+- BT1035 boot must send `AT+AUXCFG=3` and `AT+I2SCFG=67` (I2S from ADAU1701).
 
 ## Slice 2 — Secure store + Wi-Fi STA (complete)