Hardware

March 2013

Ok, some more hardware plans. Initially I thought that Raspberry Pi would be a good choice for a groundstation. But since XEFIS runs on Qt5 and does a lot of drawing, it needs more capable CPU than some slow ARM on Raspberry Pi. GPU won’t cut it, because I’m already using Qt’s QPainter and I’m not willing to rewrite everything to OpenGL. So, Rasperry runs XEFIS rather slowly – 1 fps with EFIS and NAV displays – and doesn’t meet my needs. ;-) So I bought a mini-ITX motherboard with dual-core 1.86 GHz Atom. And then added threaded painting to XEFIS. Works fine now. 15-20 fps is OK, and it will be even more if I hide ND, which I won’t really need for FPV flying (or at least I won’t need all VORs, DMEs, airports, etc displayed).

Raspberry Pi will find its place inside the model and will run XEFIS, too, but without any “displays” – just modules responsible for automated flight, communication, etc. They are not very CPU-demanding.

There’s also a LCD panel, Chinese LG substitute, that waits to be connected to the motherboard. I had to order LVDS connector to the motherboard from China, since obviously Intel had to put a connector that’s impossible to buy in normal electronics store.

Raspberry Pi + GPS receiver, Intel DN2800MT Atom motherboard

Raspberry Pi + GPS receiver, Intel DN2800MT Atom motherboard

A brief list of what I have already:

  • Motherboard
  • LCD panel
  • Noname 16 GB SSD hard drive (Archlinux installed)
  • Knobs, switches, interfaces, 7-segment displays
  • Small TV display
  • Casing
  • Barometric pressure sensor – for airport pressure reference

Things related to the plane:

  • Raspberry Pi
  • Adafruit I²C-PWM controller (for servos)
  • GPS module
  • Barometric pressure sensor

I still need:

  • CNC-cut panels
  • MAX7219 chips for controlling switches and 7-segment displays
  • At least three 5 Ah 3-cell LiPo batteries
  • Communications modules – controlling and telemetry

And for the plane:

  • Airframe
  • IMU with compass
  • Airspeed sensor
  • Current and voltage sensor
  • Transceiver for plane control and telemetry
  • Pan-tilt mechanism for camera
  • Backup camera
  • Servos, motor, etc.

Maybe I’ll try to hack EagleTree Airspeed sensor, will see. They don’t have any documentation, so they’re basically useless if not used with other EagleTree modules, unless someone tries to figure out their communication.

Since I don’t plan to put radio modules inside my groundstation, I’m not worried about them now. Let’s say that radios will be a separate station.

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