# Overview & Initial Setup

The CBU-CM405-FC is a small RPAS flight controller designed to mount directly to a Raspberry Pi Compute Module 4 (CM4). It measures just 55x40mm and weighs 16g. All flight control is processed on the STM32, allowing the CM4 to run any OS, no need for a Real Time Kernel!

* 5v, 3Amp Regulator  
* MCU: STM32F405
* IMU: 1x ICM20602, 1x BMI270
* Barometer: BMP280
* Dual Micro SD Card slots
* 5x UARTs (1 reserved for CM4) (Female Headers)
* 1x I2C
* 2x ADC (Voltage + Current Sense)
* 2x MIPI CSI Cameras (2 Lane-CAM0 & 4 Lane-CAM1)
* 4 Port USB Host Hub (Male Headers)
* DFU/EMMC/Telemetry Micro USB Ports

## Initial Setup

Upon removing from the packet please inspect for damage. 

1. Slide both [DIP Switches](https://wiki.cbunmanned.com/wiki/products-eol/cbu-cm405-fc-eol/dip-switch) to the ON position
2. Connect the micro USB port to the PC avoiding USB extensions. See notes on [power supply requirements](https://wiki.cbunmanned.com/wiki/products-eol/cbu-cm405-fc-eol/power-requirements).
3. [Flash ](https://wiki.cbunmanned.com/wiki/products-eol/cbu-cm405-fc-eol/flashing-guide)the STM32 with the latest available [Firmware](https://wiki.cbunmanned.com/wiki/products-eol/cbu-cm405-fc-eol/firmware-build-files).
4. Disconnect power.
5. If using with a CM4, Slide both Dip Switches to OFF. If no CM4 is installed Slide Only "1" to OFF.

| Dip Switch | For Flashing | With CM4 Installed | Without CM4 Installed |
| ---------- | ------------ | ------------------ | --------------------- |
| 1 - DFU    | ON           | OFF                | OFF                   |
| 2 - 3v3    | ON           | ON                 | OFF                   |