This firmware is for use on the SI4732 (ESP32-S3) Mini/Pocket Receiver

Based on the following sources:

• Volos Projects: https://github.com/VolosR/TEmbedFMRadio
• PU2CLR, Ricardo: https://github.com/pu2clr/SI4735
• Ralph Xavier: https://github.com/ralphxavier/SI4735
• Goshante: https://github.com/goshante/ats20_ats_ex
• G8PTN, Dave: https://github.com/G8PTN/ATS_MINI

Check out the Releases page.

The hardware, software and flashing documentation is available at https://esp32-si4732.github.io/ats-mini/

• GitHub Discussions - the best place for feature requests, observations, sharing, etc.
• TalkRadio Telegram Chat - informal space to chat in Russian and English.

This fork (mattafaak/ats-mini) contains significant refactoring, new features, and stability fixes beyond the upstream.

The web dashboard has been rebuilt with five tabbed pages and live polling:

• Status — signal bars, station info (RDS/EiBi name), RSSI/SNR, audio mute state, WiFi status, clock, and memory list. Auto-refreshes every 5 seconds via /api/status.
• Controls — full radio control from the browser: tune (kHz/Hz input), volume, mute, band/mode/step/bandwidth cycling, AGC/ATTN, seek up/down, sleep, and brightness. All controls use fetch() POST to /api/command.
• Memory — 99-slot memory table showing slot, frequency, band, mode, and station name (from EiBi or RDS). Names are saved alongside frequency on memory store.
• Scan — scan-to-memory with auto (top-N by RSSI) and manual (bookmark) modes. Progress bar, real-time frequency/RSSI display, result table with station names.
• Config — unchanged from upstream (WiFi credentials, theme, UTC offset, firmware update).

Theme sync: /api/theme serves the current theme's colors as CSS custom properties. All pages dynamically re-theme without a full reload.

Full auto-scan and manual-scan-to-memory, driven asynchronously from the main loop:

• Auto mode: sweeps the current band measuring RSSI per step, selects the top-N frequencies, tunes each with an 80ms settle and RDS dwell (FM), then saves to the next empty memory slots with station name.
• Manual mode: tune to a frequency and bookmark it via the Scan page. Stop the scan to save all bookmarks to memory.
• Non-blocking: the sweep and save phases run one step per main-loop tick, so the web server never blocks. The web UI polls /api/scan for progress (0-100%) and results.
• EiBi integration: on SW bands, station names are identified via EiBi database matching during the save phase.

• BLE thread safety: all NimBLE ring buffer operations (rxBuf/txBuf) are guarded by portMUX_TYPE critical sections to prevent data corruption on dual-core ESP32-S3 between the NimBLE host task and the main loop.
• BLE flush() timeout: prevented infinite spin when onStatus never fires by adding a 500ms timeout.
• WiFi reconnection watchdog: detects link loss and reconnects immediately (bypassing the 3-second CONNECT_TIME debounce) with a 10-second cooldown to prevent rapid cycling.
• Audio mute state machine: audioTempMute(false) and audioMuteForce(false) no longer corrupt the effectiveMuted state when squelch or main mute is active.
• Web security: HTTP basic auth enforced on all sensitive endpoints (/setconfig, /api/command, /api/theme, /api/scan). Station/program names are JSON-escaped to prevent injection.
• SSB frequency display: negative BFO values no longer wrap to garbage due to unsigned arithmetic.
• millis() overflow: all periodic-task timestamp variables changed from signed long to uint32_t, preventing runaway behavior after 24.8 days of uptime.
• EIBI: fixed binary search off-by-one (right = total - 1) and unsigned underflow in eibiPrev().
• Menu corruption: short menus (Sleep mode, Mode) no longer show duplicate entries.
• Scan correctness: per-frequency RSSI stored at bookmark time (not stop time). Non-contiguous empty memory slots handled correctly.
• BLE light sleep: bleStop()/bleInit() called around CPU light sleep so NimBLE survives sleep cycles.
• BLE Central disconnect check: fixed inverted condition that prevented reconnect on disconnect failure.

• Adaptive main-loop delay (5ms during activity, 20-50ms at idle) reduces CPU wakeups.
• Background redraw conditioned on minute change instead of every loop.
• F() macro for hot-path display strings to keep strings in flash.
• Reduced blocking delays in WiFi init and seek operations.
• pow() for integer step computation replaced with a lookup table.
• String::reserve() used in all HTML builders to avoid O(n²) reallocation.
• Scan-to-memory candidates heap-allocated instead of 800+ bytes on the 8KB web server task stack.
• Menu changes save only settings (SAVE_SETTINGS) instead of all bands and memories (SAVE_ALL), reducing NVS wear.

• RadioState struct: all global state consolidated into a single RadioState radioState struct for improved cache locality and debuggability.
• Module extraction: EventHandler, Scheduler, WiFiManager, WebServer, Tuning, AudioManager (4-channel mute state machine), DisplayController (ST7789 sleep/brightness), MenuDraw, MenuData, and RadioDriver (SI4732 abstraction) extracted from monolithic files into focused modules.
• BleBase: shared BLE lifecycle and abort-flag logic consolidated into a single header.
• Tuning.h: tuning and BFO commands factored out of ats-mini.ino.
• Compatibility macros removed after full migration.

The test suite has grown from 27 to 44 tests covering:

• Serial command protocol (volume, mode, step, bandwidth, band, AGC/ATTN, frequency entry, brightness, sleep, calibration, memory, seek, scan, abort, timeout recovery)
• Web API (/api/status, /api/command tune/volume/mute/band/seek, /api/theme get/set, /api/scan auto/invalid)
• HTML page loading (status, controls, scan, memory)
• Theme sync verification
• Volume adjustment on quiet frequencies (no audio artifacts)
• Mute-before-operation pattern for all band/frequency changes

Run with: python3 ats-mini/test_serial.py (requires pyserial).

Based on esp32-si4732/ats-mini by the original authors listed above. Fork maintainer: @mattafaak.