Pixhawk serial ports multiplexer

I’m building a new quadcopter with two gps, optical flow sensor, osd, telemetry, 3 axis gimbal (storm32)
Each if this components use serial port, but pixhawk seems to haven’t more than 4 physical and virtual (according to parameters list) serial ports.

Could you say if its possible to multiplex serial ports or at least use the usb connector… ?

I think you could probably connect the optical flow and the OSD to the same port, since OSD is only receiving (at least mine is) and the optical flow is only transmitting, as long as the use the same protocol at the same baudrate.

I was planning to connect optcal flow on USB

I use minimosd, I see on minimosd arducopter wiki " To connect to APM 2.5 and 2.6, use a 5-pin splitter cable that allows the telemetry port to be connected to both a SiK Radio and the MinimOSD."


Its not the same connector as pixhawk but I think that protocol and firmware major part are the sames.

Someone can confirm it ? :slight_smile:

Can I do the same thing with the two gps (same protocol)… ?

You can practically put as many ‘read only’ devices (like OSD, maybe the gimbal?) on a serial port since all they are doing is reading a serial stream

  • What optiflow sensor are you using? Some can use I2C instead of serial.

  • If you are using HERE or Zubax GPS, you can use CAN instead of serial. That might require Copter 4.0 which is still in beta, though.

  • Pixhawk may be capable of using Serial5, I don’t remember. The Cube definitely can.

I use ThoneFlow-3901U (UART) as optical sensor

storm32 gimbal doesn’t seems to use same serial protocol than OSD/Sik Radio

Could you say if I should put the two gps modules as close as possible each-other or keep a distance between them ?

Each antenna will block some sky for the other. Space them apart to lower the angle.

Also, if there’s badly shielded active circuitry at the antenna, noise is generated. With your everyday 25x25 mm ceramic patch, reception gets ugly fast.

1cm space is suffisent ?

I can put the gps 5cm away from each-other.

It sufficient to avoid EMI problems… ?

its good to cover each gps module with cooper tape… ?