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Altimeter and auto altitude


(Etienne Demers) #1

Hello guys,

ever thought about adding an altimeter to your list of sensors?

This would be a good addition especially with auto-altitude functionality.

BR2 seems to be a good platform for small work projects. Some of these project include water tank inspections. Since the clients may be filling during inspections, depth measurements gets a bit tedious for referencing anomaly elevations.

Cheers,
E.


(Jacob) #2

We are working on an altimeter! There is also support in software for altitude hold. I used this 3200$ micron echosounder to test the software. The price tag on ours will be quite a bit lower :blush:.


(Etienne Demers) #3

Nice one. Yeah, we need one that is not that expensive. Any ETA?

I’ve been looking at the echo sounders for fishing. Have sent a few emails out. Lets see what comes up.


(Tim) #4

Jacob,

Have you developed or planning support for NMEA 0183 depth sentences? I still have an Airmar DT800 that I want to integrate with my BR2…

Here’s the previous discussion on that:


(Etienne Demers) #5

Hi Tim,

you could use an arduino to convert the NMEA string to 0-5V…

Cheers,
E.


(Tim) #6

Hi E.,

I do appreciate the advice. I understand that solution may be “simple” to most, but it’s sadly beyond my abilities at the moment. Plus it seems like extra hardware and coding that ought to be unnecessary. The device outputs perfectly good RS422… in my noob mind, ideally I should be able to connect that directly to an appropriate interface on the Pixhawk or Raspberry and have that translated into a usable altitude parameter. I’m hoping this will be implemented someday.


(Etienne Demers) #7

Hello Jacob,

Out of curiosity. For auto-altitude / auto-depth, do you connect the altimeter output to the pressure sensor J402 on the pixhawk and use a relay to switch from altimeter to depth sensor?

Cheers,
E.


(Jacob) #8

The transition is done in software, and the autopilot will read both sensors simultaneously.


(Jacob) #9

This would be trivial to add (let me know when you need it), no need for extra hardware or analog signals.


(Tim) #10

Many thanks Jacob. Still trying to finish my ROV, so no sooner than about a month from now for me, but there are probably others waiting as well. I appreciate your responsiveness!


(Drew Fulton) #11

Hey Jacob,

I have just ordered a DT800 and would love to implement the NMEA 0183 depth sentences really soon. No idea what it would take to include but I’ll be receiving the unit next week and doing some field testing over the next couple weeks. My main field work isn’t until April so not 100% needed by then but it would save me from having to come up with a work around. Thanks!
Drew


(k.deboer) #12

Hey Drew,
How are you planning on installing the DT800? Will it fit in a 2" enclosure? Having an altitude hold feature would be a great option for sure.
Ken


(Drew Fulton) #13

Tim said that it should fit in a 2" enclosure with a little bit of sanding. My DT800 arrives tomorrow evening and I have a spare 2" enclosure so I’m hoping that works. If not, I’ll get a 3" enclosure and cut it down. My plan is to mount it inside the enclosure and then mount the wet side inside a water filled enclosure so that I can prevent pressure. I’ll do some testing to see how the plexiglass in front of the actual sensor impacts the readings. Unfortunately, I probably won’t get it hooked up and tested right away unless it fits in the 2" enclosure. I’ll post back when I have some progress.

Some quick research last night looks like connecting it to the Pi via USB shouldn’t be too hard (adapter also arrives tomorrow). There are some python libraries that will read the NMEA sentences so I’ll probably incorporate that into my existing software and then incorporate it into the ROV somehow. Lots of software development to do in the next 48 hours!


(Jacob) #14

It should be just a couple lines to add support:


(Etienne Demers) #15

Hello Jacob,

I am getting the micron altimeter and would like more info on how to hook it up.

Thank you,
E.


(Jacob) #16

I had connected it to a custom pcb with a microcontroller with code to read the altimeter, and send the data to the ROV via MAVLink.

There is no support for this at the moment, but I may be able to add something quickly. The driver will depend on the options you ordered the micron with. Please provide me with those details, and the documentation in case I can’t find mine.


(Etienne Demers) #17

I’m unaware of any options.

Can you tell me what you need?


(Jacob) #18

If I remember correctly, there was an option for polled vs freerunning mode, and another for output format.


(Etienne Demers) #19

These options are set by software. There is also a 0-5v output, wouldn’t that be easier to interface?


(Jacob) #20

These options are set by software.

They are not end-user configurable as I’m aware. I need the documentation.

There is also a 0-5v output, wouldn’t that be easier to interface?

Not for me!