DJI O4 arming with Raspberry Pi Pico

Custom Raspberry Pi Pico firmware provides the ARM/DISARM state used by the DJI O4 bench setup. A wired UART/MSP connection brings the unit into a repeatable test state and supports integration with Linux-side test control.

The problem

RF experiments are much easier to compare when the transmitter starts from a known state every time. Manually powering, arming and configuring a test unit introduces variation and makes longer automated test sequences difficult to reproduce.

How Pico provides the arming state

The Pico runs a custom MSPv1 endpoint over UART at 115200 baud. It handles the FC-style messages used by the test setup and reports the armed or disarmed state to O4. The host interface provides status and test commands, allowing the serial exchange and state changes to be checked during a run.

Architecture

Confirmed on the bench

The controller can reproduce arming/disarming behaviour used by the test setup and provides a deterministic way to bring the O4 unit into a known bench state. The setup also demonstrated voltage telemetry in the goggles and a working DisplayPort OSD path used during development.

Integration with the automated bench

The automated test rig combines the Pico serial controller with relay-based power control and an independent hardware cutoff. This gives repeatable runs with defined start and stop conditions. The arming interface is a separate part of that wider test arrangement.

What this enables

With power and control under software supervision, a Linux host can run repeatable experiments, associate captures with known transmitter state and retain evidence from each test. This is more useful for Sky Serpent development than manually operating the transmitter for every capture.