TalkCtrl

A private app for your Cardo motorcycle intercom: settings, FM radio, intercom and firmware updates, without an account.

TalkCtrl controls Cardo Packtalk, Freecom X and Spirit intercoms over Bluetooth, as a private replacement for the Cardo Connect app. It needs no Cardo account and sends nothing about you anywhere. The only time it goes online is when you tap Check for update or Download on the firmware screen, and then it only asks Cardo's public update server for your model's firmware.

Part of the Ctrl series by VKNXWorks.

Tested on: none yet. TalkCtrl was written from how the Cardo Connect app talks to the units (see PROTOCOL.md), but the developer doesn't have a Cardo unit. Settings that the Cardo app's code shows clearly are enabled; anything that isn't clear is shown greyed out as "Needs confirming on your unit". The firmware transfer is not yet tested on a real unit. Reports from Cardo owners are very welcome.

Features

• Connect over Bluetooth LE, the way the Cardo app does on current units, with classic Bluetooth (RFCOMM) as a fallback in Settings. TalkCtrl remembers your unit and reconnects when you open it
• Unit info: battery and charging, firmware version, name (rename it), serial number (shown on the phone only, after a tap)
• Volumes: speaker (prompts), intercom, music, phone and FM, plus how loud music stays during an intercom call
• Sound: automatic (speed-based) volume, audio profiles (EQ), music sharing, phone and intercom together
• Voice: voice prompts on or off, prompt language (from the languages your unit has), voice commands
• Microphone: VOX sensitivity and noise gate
• FM radio: on/off, tune to a frequency, seek, scan, auto tune, six presets (play and edit), region and RDS
• Intercom: mesh groups (create, join, add riders, stop, mute, bridge to Bluetooth intercom, delete), Bluetooth intercom channels A/B/C (pair, call, end, conference, reset riders), speed dial number and call
• Profiles: save the unit's volumes and settings as Solo, Duo and Group and switch with one tap
• Factory reset, with a confirmation
• Firmware update: check Cardo's update server for your model, read what's new, download, or load a .bin, .fot or .tar.gz file yourself. Installed with Qualcomm's standard GAIA upgrade, with progress, Abort and resume. TalkCtrl refuses firmware that isn't newer than the unit's and needs at least 50 % battery
• App lock with its own PIN and optional fingerprint unlock, and Hide in screenshots / Hide in recent apps (all off until you turn them on)
• Ctrl / Signal look, shared by every Ctrl app: dark and light, high contrast, one violet accent, Space Grotesk and JetBrains Mono

Not in TalkCtrl: Live Intercom and other cloud or internet features, Cardo accounts, paid feature unlocks, crash detection and SOS. VOX on/off and mesh private chat are shown but greyed out until they can be confirmed on a real unit.

Requirements

• Android 15 or newer, on a 64-bit ARM phone with Bluetooth LE
• A Cardo unit that the Cardo Connect app supports with its newer protocol (Packtalk Edge, Neo, Pro, Outdoor, Custom; Freecom 2X/4X; Spirit and their brand editions). Older units (Packtalk Bold/Slim, Freecom 1–4+, SmartH) use an older protocol; TalkCtrl warns if it sees one
• Works on any Android ROM as a normal app: stock Android, LineageOS, GrapheneOS, CalyxOS, /e/OS and the phone makers' own systems. It doesn't need root.
• Google-free and de-Googled: no Google Play services, Firebase or other Google libraries, and the app never contacts Google.

Install

1. Open the latest release on your phone, scroll down to Assets and tap the file that ends in .apk (for example TalkCtrl-v0.1.0.apk). The "Source code" zip and tar.gz files are not the app; you don't need them.
2. Open it on your phone. Android may ask you to allow installing apps from your browser or file manager.
3. Updates install over the old version. Your settings are kept.

Automatic updates: on your phone, tap the Obtainium button above. Install Obtainium first; the button adds TalkCtrl and installs every new release for you. If the button doesn't open the app, add https://github.com/VoidedKN0X/TalkCtrl in Obtainium by hand.

Getting started

1. Pair your Cardo unit with the phone in Android's Bluetooth settings as usual.
2. Open TalkCtrl, allow Nearby devices, tap Find units and pick your unit.
3. The Unit tab shows the battery, firmware and name, your profiles, firmware update and factory reset. Audio, Radio and Intercom hold the rest.
4. Settings (profile picture): connection type and privacy.

Firmware updates

Check for update sends one HTTPS request to update.cardosystems.com/firmware/<model>/fw_info.json, where <model> is the model you picked (for example Packtalk_Edge). What's new fetches fw_release_notes.json from the same folder, and Download fetches the firmware file the server names, in the voice prompt language you pick. That's all: no account, token, serial number or device ID, a fixed User-Agent: TalkCtrl, no cookies, and TalkCtrl refuses to download from any other address.

You can also load a firmware file yourself (.bin, .fot or Cardo's .tar.gz) and tell TalkCtrl its version.

The transfer uses Qualcomm's standard GAIA upgrade over Bluetooth LE, as the Cardo app does (GAIA v1/v2 for most units, GAIA v3 for Flow Lite, chosen from the model you pick): TalkCtrl asks the unit to get ready, unpacks Cardo's .tar.gz, then connects, syncs (so an interrupted transfer resumes where it stopped), sends the file in acknowledged chunks, lets the unit check it, restarts it into the new image and confirms the update. The unit checks Cardo's signature and keeps its old firmware until the new one is confirmed. This transfer is not yet tested on a real unit. Keep the screen on (TalkCtrl does that while the transfer screen is open), the unit close and charged to at least 50 %.

Is it safe to install?

• Open source. All of TalkCtrl's code is in this repo, under the GPL-3.0 licence. Anyone can read it.

• Built by GitHub, not on a personal computer. Every release on the Releases page is built by the build workflow on GitHub Actions, straight from the code in this repo. Each build also checks the app's permissions and that it has no Google libraries.

• Always signed with the same key. Android refuses to install an update signed with a different key over TalkCtrl. The SHA-256 fingerprint of TalkCtrl's signing certificate is:

  58:23:2D:34:2F:39:95:FD:F2:12:2F:E2:2A:F1:9E:DB:B5:9C:23:55:68:13:8B:6E:36:4E:A3:15:70:8B:A9:82
  

  Advanced users can check it with AppVerifier.

Check a download. Every release is built and published by GitHub Actions, never on a personal computer:

• The release notes end with the APK's SHA-256 checksum. Compare it with sha256sum TalkCtrl-vX.Y.Z.apk (or Get-FileHash on Windows).
• Each release APK has a signed build provenance attestation. With the GitHub CLI, gh attestation verify TalkCtrl-vX.Y.Z.apk -R VoidedKN0X/TalkCtrl proves it was built by this repo's workflow from the tagged commit.
• The signing-certificate fingerprint above stays the same for every release.

Permissions. TalkCtrl has no location permission.

Permission	What TalkCtrl uses it for
Nearby devices (Bluetooth scan, neverForLocation)	Finding your unit. Android can't use it to work out where you are.
Nearby devices (Bluetooth connect)	Talking to your unit.
Internet	Only the firmware check, release notes and download you start yourself, to update.cardosystems.com over HTTPS. The code refuses every other host; the build checks this permission list.
Foreground service (connected device)	Keeps a firmware transfer going if you leave the app, with a progress notification and Abort.
Notifications	That progress notification.
Use biometric hardware	Optional fingerprint unlock for the app lock.
Hide other apps' floating windows over the PIN screen	While the lock or PIN screen is showing, other apps' floating windows are hidden over it.
App-internal broadcasts (com.vknxworks.talkctrl.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION)	Added by AndroidX so that only TalkCtrl itself can send to its own internal receivers.

See Privacy for what happens to your data.

App lock

Turn the app lock on under Settings > Privacy and security > App lock. It's off until you turn it on.

• Its own app PIN of at least 6 digits, separate from your phone's screen lock. Very obvious PINs such as 111111 or 123456 are refused.
• Unlock with fingerprint (optional) only accepts strong biometrics, checked by the phone's secure hardware. The PIN is still needed after the phone restarts and at least every 72 hours.
• The PIN is never stored. It's stretched with 600,000 rounds of PBKDF2 and mixed with a key held in the phone's secure hardware.
• Wrong PINs: after 5 tries you wait 30 seconds, doubling up to 15 minutes. Restarting the app or the phone, or changing the clock, doesn't skip the wait.
• Forgot your PIN? It can't be recovered. The lock screen offers to forget your unit and saved profiles and turn the lock off. Nothing on the unit itself is changed.

Privacy

Telemetry-free. TalkCtrl has no analytics, crash reporting, usage stats or tracking of any kind.

• Bluetooth only, to your unit. Everything TalkCtrl does to your intercom goes over Bluetooth between your phone and the unit.
• One kind of internet request, only when you tap it: the firmware check, release notes and download, to Cardo's public update server, carrying only the model name in the address. No account, serial number, device ID or location.
• No cleartext: the network security configuration forbids unencrypted connections.
• The serial number is shown on the phone only (after a tap) and never sent anywhere.
• The remembered unit (its Bluetooth address and name), your profiles and settings are in TalkCtrl's private storage. Android backups don't include them, and TalkCtrl is left out of Android's cloud backup and its phone-to-phone transfer.
• The Support, Report a bug, Source code and Licence links on the You page open in your browser, only when you tap them.

How TalkCtrl is made

TalkCtrl is a one-person project by VoidedKN0X (VKNXWorks). Much of the code is written with the help of AI (Claude, by Anthropic). I decide what the app does, review the changes and use the app myself. Every change is listed in the changelog, and you can read every line of code here.

The protocol notes in PROTOCOL.md were made by reading the Cardo Connect Android app, only to make TalkCtrl work with Cardo units you own. No Cardo code or assets are in TalkCtrl. TalkCtrl isn't made by, affiliated with or endorsed by Cardo Systems; Cardo, Packtalk and Freecom are their trademarks.

Build from source

You need Android Studio, or JDK 17 or newer and the Android SDK.

1. Clone the repo:

   git clone https://github.com/VoidedKN0X/TalkCtrl.git
   cd TalkCtrl

2. Build the app:

   ./gradlew assembleDebug

   On Windows, use gradlew.bat assembleDebug. ./gradlew testDebugUnitTest runs the protocol tests.
3. The APK is in app/build/outputs/apk/debug/. Copy it to your phone and install it.

Dependency verification. Every library and build plugin download is checked against the sha256 checksums in gradle/verification-metadata.xml, and the build fails on any mismatch. When you change a dependency, a plugin or the Gradle version, run the Dependency verification metadata workflow (Actions tab, Run workflow), check the diff of the file it prints and commit it in the same push.

Support the project

TalkCtrl is free and open source. If it's useful to you, you can support development on GitHub Sponsors. Please report bugs and ideas with the bug report and feature request forms. If you have a Cardo unit, telling which features work on it helps the most. Starring the repo helps too.

Found a security problem? Please don't open a public issue; see SECURITY.md.

The Ctrl series

Native Android apps for self-hosted services and everyday tools, all with the same design.

App	What it's for
AdCtrl	Control your AdGuard Home DNS server
ArrCtrl	Radarr, Sonarr, Prowlarr, Bazarr, qBittorrent, autobrr and Cleanuparr in one app
BeamCtrl	TV remote for phones with an IR blaster
CallCtrl	Phone app: dialer, call history and in-call screen
CameraCtrl	Private camera with RAW (DNG) on every lens
ChatCtrl	Matrix chat client for matrix.org and self-hosted Synapse
ClockCtrl	Alarms, timers, stopwatch and world clock
ContactCtrl	Contacts: browse, edit, import and export
CraftyCtrl	Manage Minecraft servers on Crafty Controller
DateCtrl	Calendar for the calendars on your phone and your accounts
FilesCtrl	File manager with NFS, SMB, SFTP, FTP and WebDAV
FrigateCtrl	Watch and review your Frigate NVR cameras
GalleryCtrl	Private, offline gallery with an encrypted vault
ImmichCtrl	Photos and backup for your Immich server
JellyCtrl	Movies, shows, music and Live TV from Jellyfin
LijnCtrl	Live De Lijn bus and tram departures
LumenCtrl	Private, offline photo and video editor
MailCtrl	Email for Gmail and Proton Mail
MapsCtrl	Private, offline maps and navigation
MemoCtrl	Notes on your Memos server
NaviCtrl	Music player for Navidrome servers
PaperCtrl	Scan and browse documents on Paperless-ngx
PrintCtrl	Bambu Lab printers through Bambuddy, and Spoolman spools
ProxCtrl	Manage your Proxmox VE server
RecorderCtrl	Private, offline voice recorder
RideCtrl	Offline maintenance, fuel and mod log for your vehicles
SeerrCtrl	Request movies and shows on Seerr / Jellyseerr
ShutterCtrl	Remote control and photo transfer for Canon cameras
SoundCtrl	JBL headphones and speakers, without the account
SumCtrl	Offline calculator, unit converter and work tools
SynapseCtrl	Administer your Matrix Synapse server
TalkCtrl (this app)	Cardo intercom settings, radio and updates
TapoCtrl	Tapo plugs and bulbs on your home network
TextCtrl	Private SMS and MMS messaging
TrueCtrl	Monitor and manage your TrueNAS server
WakeCtrl	Keep the screen awake, per app or while charging
WrtCtrl	Manage your OpenWrt router

License

TalkCtrl is licensed under the GNU General Public License v3.0. © VKNXWorks

Fonts, bundled in the app (nothing is downloaded): Space Grotesk and JetBrains Mono, both under the SIL Open Font License 1.1 (FONT-LICENSE-SpaceGrotesk.txt, FONT-LICENSE-JetBrainsMono.txt).