Wiring

There are three methods of hooking up the board.

Option 1 - Direct Bluetooth Connection

This option requires transmitter that has a Bluetooth training module. Some transmitters, like FrSky, have this module preinstalled. Others, like Radio Master TX16s, allow adding this module by the user. See Add in Bluetooth Module.

The picture above shows 2 different ways for powering the board. Setting power to one of the inputs will be enough. Although, voltage can be applied to both power inputs at the same time. In this case it is very important that the battery voltage should be not less than +5V. USB is connected to VIN via a Schottky diode. After that, power goes from VIN to the internal 3.3V regulator. So, if voltage on VIN will be less than the voltage on USB, the USB port will start charging the battery with uncontrolled current. The results will most likely be catastrophic. So, applying more than +5V to VIN will be always safe regardless if the USB cable is attached or not.

Option 2 - Wired connection

The Nano 33 BLE board is attached to the transmitter with a cable. Standard PPM connector does not have a power line in it. In this case battery or power from the USB port is required. The SBUS connector on the transmitter may have a power line. In this case it would be possible to power the Nano 33 BLE board from the transmitter.

!!! Some radios have been found to output too high a voltage on the trainer port. So far just the Spektrum DX18. This is causing the Nano 33 BLE to fail. Please see, DX18 for a solution using a Zener diode to prevent high voltages on the PPM pin.

Option 3 - Bluetooth Bridge

This option is a combination of the first and the second. The first board operates in the same way as it works in the option 1, while the second board operates like in the option2, except it gets data from the Bluetooth connection instead of its IMU module.