FYT Radio

A clean, drop-in replacement UI for the FYT (Feiyiteng) head unit's stock AM/FM tuner (com.syu.carradio). Side-loads as a normal user app; the stock radio stays installed because the actual tuner chip lives on the MCU and the stock app is what we send commands to over SYU's private IPC.

Why this exists: the stock radio UI has too much going on. This is a quiet, legible front-end for the same tuner: big frequency readout, six presets, and not much else.

Built for the 768×1024 vertical "Tesla-style" FYT screen, the UIS7870 ("7870") units, portrait 768 px wide × 1024 px tall. It should work just as well on the related 7862 boards (same SYU com.syu.ms IPC + com.syu.carradio stack); only the FM frequency-unit encoding differs by firmware and the app auto-detects that. Other resolutions aren't laid out for.

Installs on Android 8+ (minSdk 26) so it runs on older units like the UIS7862 (Android 10). It's a single universal APK. Install it directly; you don't need SAI or any split-APK installer.

Non-rooted. Coexists with the stock apps rather than replacing them.

Screenshots

FM tuner · AM band · settings (theme, Material You / accent + custom color, auto-start). Shown full-screen on the 768×1024 unit.

What's built

• Large frequency display (FM rendered as 101.1 MHz, AM as 1010 kHz), animated on change. The MCU's frequency unit (kHz vs. dekahertz) is auto-detected, so the readout is correct across firmwares.
• AM/FM segmented band toggle.
• RDS: station name (PS), scrolling radio text (RT, the closest thing radio has to a "now playing" line), a genre/PTY chip, plus stereo + a "live" lock dot. (FM-only, signal permitting.) There's deliberately no signal-strength meter: the SYU radio module doesn't expose a reception level, so rather than fake a bar graph we show what's real (RDS lock + stereo).
• Opens on your last station (remembered across launches) and highlights the preset you're currently tuned to.
• Power button in the frequency-card corner. On = radio becomes the active MCU audio source (C_APP_ID → APP_ID_RADIO) and audio is unmuted. Off = the audio is muted (sound module C_VOL → VOL_MUTE) while we keep holding the radio source, so no other app (Bluetooth/Spotify) auto-resumes, a truly silent "off". Leaving the app while off auto-unmutes and releases the source, so the unit is never left stuck muted.
• Tune ± step (◁▷ = one channel step, press-and-hold to keep stepping), seek ± (⏮⏭ = auto-seek to the next station), and a center SCAN that sweeps the band and auto-stores presets ("auto discover").
• 6 presets per band, persisted in SharedPreferences. Tap to recall, long-press to save the current station. The RDS station name is saved alongside the frequency when it's known, so tiles can read "92.5 / KEXP".
• Settings behind a corner gear (no extra tab): theme (System / Light / Dark, defaults to System), accent color (preset swatches, an arbitrary custom color picker with hue + saturation/value, or Material You to pull the accent from the device's colors), plus the auto-start and force-mono (cleaner weak-FM audio) toggles.
• Start radio when app opens (on by default): on launch, and whenever you switch back to the app from Bluetooth/another source, the radio reclaims the MCU audio source, pausing whatever else was playing. Turn it off to leave the current source alone until you tap power.
• "No tuner feedback yet" diagnostic panel that lists the last 20 SYU module updates received, handy for confirming the MCU is awake and talking (see NOTES.md).

Project layout

app/
  src/main/AndroidManifest.xml
  src/main/kotlin/com/fytradio/
    MainActivity.kt
    radio/
      RadioController.kt     ← StateFlows + IPC callback handling, all command logic
      SyuRadioBridge.kt      ← raw IBinder transact to com.syu.ms (toolkit + modules)
      PresetStore.kt         ← SharedPreferences-backed presets (freq + RDS name)
      RadioModels.kt         ← Band, Region, TunerState, formatters
    ui/
      RadioScreen.kt
      FrequencyDisplay.kt
      BandSelector.kt
      TuneControls.kt
      PresetGrid.kt
      SettingsDialog.kt      ← theme / accent / auto-start
      theme/Theme.kt
  src/main/res/values/{strings.xml,themes.xml}
.github/workflows/{build.yml,release.yml}
build.gradle.kts                 ← root
settings.gradle.kts
gradle/libs.versions.toml

RadioController is the only class that talks to the SYU bridge. UI is dumb Compose: every screen consumes StateFlow and emits callbacks.

Releases & updates

Pushing a vX.Y.Z tag triggers .github/workflows/release.yml, which builds a signed release APK and attaches it to a GitHub Release. Grab the latest from the Releases page, copy it to the unit, and install.

Every release is signed with the same key (held in the repo's Actions secrets), so new versions install in place over an older release. No uninstall, no signature conflict. versionCode/versionName are derived from the tag automatically.

One-time note: if you're currently running a locally-built debug APK, uninstall it once before installing the first signed release (debug and release use different keys). After that, every release upgrades in place.

Cutting a release:

git tag v0.1.0 && git push origin v0.1.0    # CI builds + publishes the signed APK

Build & deploy to the unit (development)

Wireless debugging only; the head unit has no usable USB-data port. The adb port rolls on every reboot.

# 1. connect (port changes each reboot)
adb connect 192.168.158.192:<current_port>
adb devices                                    # confirm exactly one device

# 2. build a debug APK
cd ~/FytRadio
./gradlew :app:assembleDebug

# 3. install + launch
adb install -r app/build/outputs/apk/debug/app-debug.apk
adb shell monkey -p com.fytradio 1

No signing setup needed for debug builds. Same pattern as FytBt.

Bench power (READ THIS if the tuner shows no live data)

These units watch the ACC/ignition line separately from constant B+ to decide they're truly powered on. With only one 12 V rail connected, the Android SoC stays alive (post-ignition keep-alive) but the MCU parks in standby. Its Qin log shows mcuState 23 / sTopAppWhenMcuOff, and the tuner chip stays unpowered. Commands are still accepted, but you get no frequency / RDS / signal back.

On a bench, wire both to +12 V:

• B+ (constant battery, commonly yellow)
• ACC (ignition/accessory, commonly red): tie it to the same +12 V as B+
• GND (black)

Plus the antenna for actual reception. Once ACC is seen high with B+ present, the MCU comes to full power and starts emitting U_FREQ / RDS, and the live dot goes green.

What to verify on first install

1. Launch → big frequency card renders FM (P1 or the default).
2. Tap the power button (corner of the freq card) → Qin: UI Change AppId to 1 (radio is now the active source). Tap again → AppId to 0 (radio released).
3. Toggle AM/FM → the MCU echoes U_EXTRA_FREQ_INFO with that band's [min,max,step,count] (verified).
4. Tap tune ◁▷ / seek ⏮⏭ / SCAN → commands dispatch over IPC; with the MCU awake (see Bench power) the frequency/RDS update and the live dot turns green.
5. Long-press a preset slot → saves the current frequency. Tap to recall.

Known limitations

• No direct chip control. Non-rooted, so we don't drive the tuner chip ourselves; we drive the same SYU radio module the stock app uses, which drives the chip via the MCU. (Protocol fully reverse-engineered and verified; see NOTES.md.)
• Audio is invisible to Android. The radio output runs through the MCU's analog path, so we can't apply software DSP, ducking, or per-station volume.
• Live tuner data needs the MCU awake. See Bench power above.