Start developing

Start with the Cerberus N16R2 board profile, a USB data cable, and a known firmware release. Keep the onboard S3 and C5 images from the same release.

1. Identify your device

Record the board revision, installed expansion board, and firmware version. Cerberus has 16 MB S3 flash and 2 MB quad PSRAM. The C5 memory baseline is WROOM N4: 4 MB flash and no PSRAM.

The device is independently programmable on both processors. The USB connection reaches the S3. A temporary S3 bridge exposes the onboard C5 for programming through that same connector.

2. Install a working baseline

Open the Cerberus USB Installer in a supported desktop browser and follow its S3 bridge → C5 → final S3 sequence. The final S3 application must be installed and verified before the device is ready to use. The installer repository contains maintenance information.

Use a data-capable USB cable. Close applications that hold the serial port. The port can change when the bridge appears or the S3 returns to its ROM downloader.

3. Get the firmware source

The public Cerberus Sentinel repository provides a working implementation of display, touch, battery status, SD, USB, and the S3/C5 link. This Dev Board repository contains reference material and small examples; it is not a complete firmware image.

git clone https://github.com/463N7/Cerberus-Sentinel.git
cd Cerberus-Sentinel
python -m pip install platformio==6.1.19
python tools/build_sentinel.py --target all --package

These build commands do not program your device. Consult the firmware repository's build and recovery guide for its current release workflow. See programming for memory and driver constraints.

4. Confirm the built-in features

• S3 boots and reports the expected version and memory.
• LCD orientation, colors, and backlight are correct; touch works at each corner.
• Onboard C5 is online with the matched protocol/firmware version.
• A known FAT32 card mounts and passes a controlled file read/write test.
• Battery voltage and percentage are plausible, or the unavailable state is shown clearly.
• USB remains usable after resetting and cold power-cycling.

Begin expansion work only after these baseline checks pass. Keep a recovery image and record the original pin assignments.

Recover the S3 USB connection

1. Hold the board's S3 BOOT control.
2. Tap RESET while keeping BOOT held.
3. Release BOOT, select the native S3 USB port, and reinstall the final S3 firmware.
4. Reset or power-cycle into the application and confirm its version.

Use the board's S3 BOOT and RESET controls for recovery.

Next steps

Use the pinouts, review the expansion add-ons, and work through the programming guide. The RF/NFC board and six-C5 bank are expansion add-ons, and both are still in testing. Record hardware results using the compatibility-report forms linked from the repository.