OpenXSensor for DLG with 1S LiPo

[nppc]

I have 1m DLG with FrSky receiver. There is not much space left in the fuselage, but I want to install Altimeter. OpenXSensor very good candidate. The size of Arduino Pro Mini is good, but adding Pressure sensor board to it makes it difficult to fit.

So... Lets see what we can remove from Arduino Pro Mini board...
I do not need serial pads, because I already flashed OXS. Also LDO is not needed if we using 1S LiPo. And of course a RESET Button is quite huge.
With dremmel we can cut it like this (red lines) without much pain:

We can cut unneeded PCB to save weight and space.

One problem I marked with Yellow circle. We will disconnect Reset pin of ATmega from 10K pull up resistor. So, later we should restore it.

It is Arduino Pro Mini running at 8Mhz. But I think 16Mhz Arduino will work too, because it can run with no problem from 3.3V.
Flying my DLG I never let my 1S LiPo to discharge more than to 3.5 volts, but with working servos voltage can drop till 3.2 volts so, 8Mhz is much safer.

Next, lets test it...

Prototype. Everything working fine from 1S LiPo

Seems works fine. I have stable readings on my Transmitter.

Need to brush it up to make cleaner layout.

Ready to install to small DLG :)

Now we should cover the pressure sensor with some sponge and wrap it all with tape.

There is still should be done some real world tests, because I'm not sure how ms5611 board will work with 3.2 voltage. Also, maybe I need to add more capacitors to the Arduino board. We'll see...

The weight of this OXS is about 4 grams and in my DLG I have 5 grams of dead ballast, so it is will be very nice replacement.

Pavel

[nppc]

So, today I had a test of my OpenXsensor vario.
Works very well, stable and adequate readings, so no need any additional stabilization of power or decoupling.
Today was quite windy about 10m/s.
Had a flight for 21 minute with max altitude at 54 meters.
Excellent tiny vario!

Pavel

[jhsa]

Well done.

João

[nigelsheffield]

if width is the problem as dlg pods get thinner the arduino nano is fractionally narrower then the pro mini....but longer.

[frater]

I have yet to start with Arduino and therefore a lot to learn. I might be missing a lot, but anyhow....
Can you tell me why you don't have these 2 PCB's on top of each other??

[kalle123]

You "butchered" the arduino, but left the MS5611 alone.
Lot of unused components there.

[nppc]

I have yet to start with Arduino and therefore a lot to learn. I might be missing a lot, but anyhow....
Can you tell me why you don't have these 2 PCB's on top of each other??

It was not an option in my case. I have very narrow space in mine DLG. To have them on top each other will not fit. But if space no problem for you, then let it go. Maybe you do not need to cut the board at all?

Pavel