# System Architecture
The Cube system architecture incorporates two functional blocks into a single physical module.
### PWM Outputs
Eight PWM outputs are connected to the I/O.
* Can be directly controlled by the I/O via the R/C input and onboard mixing even if the FMU is not active (failsafe/manual mode).
* Supports multiple update rates in three groups (one group of four outputs and two groups of two outputs).
* Supports signal rates reaching up to 400Hz.
* Output only.
* Each PWM output can drive up to 50mA, but the total limit for all eight outputs is 100mA.
Six PWM outputs are connected to the FMU.
* Supports reduced update latency.
* Cannot be controlled by the I/O in failsafe conditions.
* Supports multiple update rates in two groups (one group of four and one group of two).
All the PWM outputs are EDS-protected and are designed to survive accidental servo misconnection without damage. The servo drivers are specified to drive a 50pF servo input load over 2m of 26AWG servo cable.
The I/O PWM outputs can also be configured as individual GPIOs.
{% hint style="info" %}
The I/O PWM outputs are not high-power outputs. The PWM drivers are only designed to drive servos and similar logic inputs and do not include relays or LEDs.
{% endhint %}
### Peripheral Ports
All peripherals are connected through a single 80-pin connector. The peripherals are connected via a baseboard that can be customized for each application.
### Base Board
The initial base board features separate the connectors for each of the peripheral ports, but with a few exceptions.
#### Serial Ports
* Five serial ports are provided.
* The serial ports operate at a 3.3V CMOS logic level. They are 5V tolerant, buffered, and ESD-protected.
* Serial 1 and 2 feature full flow control.
* Serial 3 is recommended to function as a GPS port. A safety button and possibly a safety LED are included. An I2C for the compass and RGB LED is also provided.
* Serial 4 has an I2C on the second bus, allowing two compass modules to be connected simultaneously.
* Serial 5 is available as a header underneath the board. It is used for the onboard ADSB-IN receiver that is featured on newer carrier boards.
#### SPI Port
* Not buffered. Should only be used with short cable runs.
* Signals are 3.3V CMOS logic level, but 5V tolerant.
* SPI is only available to test points on the first base board, along with a CS and INT pin.
#### Analog Inputs
* Analogue 1-3 are protected against inputs up to 12V, but scaled for 0-3.3V inputs.
* The RSSI input supports either PWM or analog RSSI. As this input shares a pin with the S.Bus output, only one of them may be connected at a time.
#### CPPM, S.Bus and DSM/Spektrum Input
These inputs remain unchanged from the previous versions.
#### CAN Ports
The CAN ports are standard CAN Bus. Termination for one end of the bus is fixed on board. The drivers are onboard the FMU.
#### Piezo Port
The piezo port drives most piezo elements in the 5 - 300nF range at up to 35V. It is extremely loud, where the achievable sound pressure level is limited by the sensitivity of the piezo element being driven.
#### I2C
I2C is direct driven, un-buffered, and pulled up to 3.3v onboard the FMU.
### Sensors
All flight sensors in The Cube are connected via SPI.
| Cube Type | Life Cycle | IMU1 | IMU2 | IMU3 | Barometer1 | Barometer2 |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------- | ------------------- | ------------------------------------ | ------------------- | ---------- | ---------- |
| Cube Black
Cube BlueF4
Cube Green
| EOL | MPU9250 | LSM303D/L3GD20 | MPU9250 | MS5611 | MS6511 |
| **Cube Black+** | EOL | MPU9250 | ICM20602 | ICM20948 | MS5611 | MS5611 |
| **Cube PurpleF4** | EOL | MPU9250 | NA | NA | MS5611 | NA |
| **CubePurpleH7** | ACTIVE | ICM20649 | NA | NA | MS5611 | NA |
| Cube Orange
Cube Yellow
Cube BlueH7
| ACTIVE | ICM20649 | ICM20602 | ICM20948 | MS5611 | MS5611 |
| **Cube Orange+** | ACTIVE | ICM45686 / ICM20649 | ICM20948 / ICM42688 / ICM45686\_EXT2 | ICM42688 / ICM45686 | MS5611 | MS5611 |
{% hint style="info" %}
* IMU1 and IMU2 are isolated.
* IMU3 is not isolated.
* Data-ready signals from any of the sensors are **NOT ROUTED on the Isolated IMU.**
{% endhint %}
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