Cube Blue flight-management module family

The CubePilot Cube Blue is a modular flight controller in the form of a flight management unit (FMU) that plugs into a separate carrier board through an 80-position Hirose DF17 connector. It is sold in two hardware versions, BlueF4 and BlueH7, and acts as the autopilot computer for multirotor, fixed-wing and VTOL unmanned aircraft. Because the processing module and the airframe wiring are separate parts, an integrator can design a carrier board once and replace the FMU later without rewiring the aircraft.

The two versions differ in processor, memory and inertial sensor. BlueF4 uses an STM32F427 microcontroller with 2 MB of flash and 256 KB of RAM, paired with an MPU9250 16G accelerometer and gyroscope. BlueH7 uses an STM32H753 with 2 MB of flash and 1 MB of RAM, paired with an ICM-20649 30G accelerometer and gyroscope. The H7 version has four times the working memory and a wider acceleration range, and it adds a CAN FD interface. CubePilot also documents that the H7 designs are the replacement path for older Cubes whose inertial sensors have reached end of life, and that they work with carrier boards following the CubePilot reference design.

Sensing is redundant. Every Cube carries three IMUs, two on a vibration-damped IMU board and one fixed to the FMU, together with two MS5611 barometers and two compasses, one on each of those boards. All sensors are connected over SPI, and a micro SD interface through SDIO provides on-board data logging.

The interface set is defined by the carrier board. The Cube provides 14 PWM servo outputs, of which eight are driven by the I/O processor and six by the FMU. The eight I/O outputs keep working from the radio-control input and on-board mixing when the FMU is not active, which gives a manual failsafe path. Receiver inputs cover CPPM, Spektrum/DSM and S.Bus, and there is one S.Bus servo output and an analog or PWM RSSI input. The unit also has five general-purpose serial ports, two of them with full flow control, two I2C ports that allow two GPS and compass units without address conflicts, two CAN buses, three analog inputs, an unbuffered SPI port for short cables, a buzzer driver, an RGB LED output and a safety switch with LED.

Power is a single 5 V supply with a compliant range of 4.0 to 5.5 V; the Cube does not include power management, so the power module sits on the carrier board. A second power input is available on the PRO carrier board, while the mini carrier board takes backup power from the servo rail. Power-monitoring signals reach the I/O chip so that power events are logged even during an in-flight reboot. The ideal operating temperature is -10 to 55 degrees C. The module is not waterproof and needs external protection. Mounting uses a 30 x 30 mm M1.6 hole pattern within a 35 x 35 mm footprint.

CubePilot offers several carrier boards for the Cube, including standard, Kore, ADS-B IN, mini and EDU450 versions, so one FMU can be matched to different airframe sizes and payload wiring. Typical uses are the flight control of survey, inspection and logistics aircraft, and OEM or development platforms that need a replaceable autopilot module.