Copter connection to ground station with USB-FTDI?


I have a USB cable from my Linux machine connected to a FTDI adaptor. The Tx/Rx pins are then connected to my flight controller’s Rx/Tx (swapped) for SERIAL4. I set the SERIAL4_TYPE to 2 and the SERIAL4_BAUD to 115.

I’m trying to connect to a flight controller using mavproxy: --master=/dev/ttyUSB0 --baudrate=115200

Here’s the strange part: It connects successfully only when I provide power to the flight controller’s usb port (SERIAL0). If I provide power from a lipo battery (through the PDB/ESCs), then I cannot connect.

What’s going on here?

The use case is connecting a drone to a TCP/IP radio (microhard) that supports a USB serial connection, then remotely connecting over a network to a ground station.

Sounds like a bad ground.

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Bad ground on the FC? Is there a way to test with a multi meter?

Bad ground in your configuration. In other words, when you power with a battery, it’s plausible that the ground is not common to the FTDI adapter connection. Confirm you have the ground wire connected to the UART port and not just RX/TX.

You were right, Yuri. Indeed there needed to be an additional wire connected between the FTDI ground and the FC ground. All is good now, connecting as expected over the network.

Thanks I appreciate it!