Arduino telemetry system?

[perhapsleiana]

I looked into radio telemetry systems, and found that frankly they just don't have what I want, and they're expensive. I looked into making something using an Arduino or similar microcontroller (preferably lighter) and found that it's really not that expensive, but I would need my coding knowledge and it takes quite a bit of soldering.

First, you need two big enough microcontrollers, one for the base station and one for the aircraft or whatever is being telemetered.
Second you need a radio link with enough range. I am using an NRF24L01 pair, both with amplifiers. The base station will use an SMA antenna mount/port, while the sensor side will use a direct soldered antenna, because everyone hates uFL. I do.
Third, you need your display. So far I'm using a laptop as a serial monitor, but it has problems with being visible in the sun, and it's big. In the future I plan to use cheapo servos to make dial gauges for my readouts.
Fourth, you need your sensors, and you can use any type of sensor currently available for premade telemetry, but it will be cheaper, and you can also use many, more sensors.
Finally, you need to power it all with a dedicated 5V low noise BEC, and an additional linear regulator ship to pull that down to 3.3V for those circuits.

• Sensor side
  • Temperatures
    • DS18B20 contact temperature sensors
      • can be bus-chained and still only take up one digital MCU pin, I believe it goes up to 64 sensors on a single pin
      • Use for ESC and battery temps, you may also want one for ambient temp
    • TMP007 Thermopile
      • Goes on the i2c bus and can measure motor bell temperatures without touching the bell, because it's a short-range IR sensor
    • Thermistors
      • Mostly to be used for motor coils, since DS18B20 sensors can only get so hot before you lost 5 bucks because it's fried doing a vertical
      • Can be put on comparators to read maximum of n thermistors, can be wired in parallel for a pseudo-average reading, can also be put on serial ADC modules for more accurate readings and measuring ALL the temperatures, including individual motor coils, wires, e v e r y t h i n g
  • Speed
    • GPS module- will also give lat/lon but mainly it's for ground speed
    • Differential pressure sensor- these are paired with Pitot tubes and well documented by Ardupilot for measuring airspeed- pair with a barometer and a DS18B20 for other types of airspeed.
  • Altitude
    • Variometers, altimeters, and other barometric pressure-based altitude readings
    • GPS altitude if you get a good GPS module
    • Laser distance sensor for timing landing flare? Probably not worth the weight.
  • Performance
    • Energy (volt/amp) meters, battery cell monitor, the usual stuff
    • Sensors that measure airframe flexing, especially the wing
  • Flight
    • Attitude/Artificial Horizon - totally possible, but not necessary for LOS
    • Acceleration- make sure your sensor can take up to 10G, but this is fun to see data on.
  • Logging
    • Yeah, throw an SD card on there for log files, why not. It'll keep going if you lose signal even.

• Base Station Side
  • Servo-dial-indicators
  • Audio warnings (using a discrete text-to-voice module)
    • If a DAC is present, you gotta decide whether you want a computer voice or an actual recorded voice
  • Probably would be nice to have a display too, especially if it's a monochrome one for speed
  • Definitely have an SD card on the SPI bus.
    • Needed for voice feedback if you are using a DAC and non-generated audio
    • Needed for any display images
    • Needed for logging
  • User-configurable warnings via a display and 4 buttons, kinda like literally every lipo charger does
  • Side note: Anyone here done an Arduino-based lipo charger with custom firmware?

So, as you can see, the possibilities are ridiculous and endless.

Question is, is this all worth it, and how good is the radio link, and will it interfere with the main flight systems?

 

[FDS]

You can put a flight controller like the Matek F405 wing into most planes and get a ton of information via FPV display either as a separate screen or HUD in goggles, plus fully programmable flight function and autonomous control, all for under $80 including a camera.

 

[perhapsleiana]

You can put a flight controller like the Matek F405 wing into most planes and get a ton of information via FPV display either as a separate screen or HUD in goggles, plus fully programmable flight function and autonomous control, all for under $80 including a camera.

Yup, that's true, but I'm talking LOS and no FC. Can't have my critical systems rely on non-dedicated hardware, and can't have my flight controls rely on sensors other than the gimbals and switches in my Tx. Also, I'm aiming for sub- $60 for the whole shebang, and I already have a lot of the hardware.
That being said, the sensor side could definitely use a FC with modified firmware- what do you recommend for an Ardupilot board under $30 for this purpose?

 

[FDS]

I have no Ardupilot knowledge, sorry!
F405 is still flown by the TX, it just has automated options. True it can’t do voice alerts but the telemetry offered by a serial receiver can be used to set voice alerts in Open TX.

 

[perhapsleiana]

I know I’m using a Nano for the sensor side now, but I’m having trouble deciding what to do for the base side. Any suggestions?

 

[perhapsleiana]

Working on my panel meter design- I call them SADs. It's nice having a creative writing major in the house.

 

[perhapsleiana]

Update: These NRF24L01 +PA modules are not easy to work with, and I'm pretty sure both the ones I got were crappy clones that didn't even work. Ordered a higher-quality new pair because I busted both the cloned ones. This is frustrating, especially with bad flying weather.