Logging NMEA XDR sentences
Hello,
I think I read carefully the various discussions about weather data logging and the NMEA reader but they keep to be distinct topics.
On one hand some users (and I) want to log some weather data like barometric pressure and temperature (both from the phone internal sensors) and on the other hand there is a great feature for data logging, the NMEA reader (if I understand what it does).
During my trips (by foot or kayak), I use to carry a small waterproof Arduino based bluetooth device (self made and $30-40) that reports the local temperature and UV index to my phone via bluetooth 4. I use a terminal App to read the values reported.
Recently, I discovered the Locus Map NMEA reader feature but I wasn't able to use it because Locus Map says it can't connect the device. I don't know why.
Even if it connected, (afaik) Locus Map doesn't decode the weather related NMEA sentences and to be honest, those are a mess.
Is there any way to do what I want? As I programmed the device, I can probably change it for another protocol (but not ANT+ as it requiers another radio module, not a standard BT 4 radio).
Or is there a plan to extend the NMEA reader?
btw I suspect, I can't connect my device because it uses bluetooth 4 instead of bluetooth 3. I am right ?
Any comment or reply to my questions will be appreciated.
Thanks.
Jean-Louis
I like this idea 
Hi Jean-Luis,
Locus can connect with BT 4.0 devices in general but probably the issue with yours is in selected protocol, try to re-program it. Nevertheless, as you correctly presume, Locus can't read weather data, only coordinates, elevation, times and other basic NMEA parameters.
Hi Jean-Luis,
Locus can connect with BT 4.0 devices in general but probably the issue with yours is in selected protocol, try to re-program it. Nevertheless, as you correctly presume, Locus can't read weather data, only coordinates, elevation, times and other basic NMEA parameters.
Hello,
It's not the reply I hoped but thank you.At least I know now that it isn't a BT problem.
Thanks.
jl
Hello,
It's not the reply I hoped but thank you.At least I know now that it isn't a BT problem.
Thanks.
jl
Hi,
we'll discuss this topic in a wider team next week. I'll let you know the result.
Hi,
we'll discuss this topic in a wider team next week. I'll let you know the result.
Good day jlp6k,
this functionality is currently not implemented in Locus Map. To be true, both NMEA readers ( BT GPS and also NMEA reader ) works only with older BT 3.0. This is one problem, second is that NMEA Reader is made mainly for reading points from NMEA messages.
I can imagine extending NMEA reading to consume also special NMEA messages with temperature and pressure data and supply these information into Locus Map system. It will anyway require improve support for 1) BT 4.0, 2) special NMEA messages.
I plan to completely rewrite BT support in Locus Map ( during 2018 ), so there should option to add support for it. For this I'll anyway need link to some official documentation for these special NMEA messages. Also are they used in some known public BT devices?
Good day jlp6k,
this functionality is currently not implemented in Locus Map. To be true, both NMEA readers ( BT GPS and also NMEA reader ) works only with older BT 3.0. This is one problem, second is that NMEA Reader is made mainly for reading points from NMEA messages.
I can imagine extending NMEA reading to consume also special NMEA messages with temperature and pressure data and supply these information into Locus Map system. It will anyway require improve support for 1) BT 4.0, 2) special NMEA messages.
I plan to completely rewrite BT support in Locus Map ( during 2018 ), so there should option to add support for it. For this I'll anyway need link to some official documentation for these special NMEA messages. Also are they used in some known public BT devices?
Hello,
I've read some information about commercial devices (mainly boat stuff) and they all provide their data through different NMEA sentences: MTW (Mean Temperature of Water) or XDR. In the later case, the data seems to be quite free which may cause some decoding problems, but it allows a wider choice of data types (in fact any kind of data collected with sensors).
As you probably know, NMEA protocol is closed. So I wasn't able to find any free recent documentation. But I collected some information available on few web sites and forums (afaik gathered by reverse engineering). Here are the more interesting ones:
As Locus Map already provides an interface with some BT4 devices, another way to solve data input problem may be to provide an open interface. You may add a "generic open BT 4 device" in the bluetooth manager with a simple protocol (e.g. a stream of <type>,<value> (maybe P,1000 for pressure,value in millibars or T,22.5 for temperature,value in Celcius)). Or it may be an "open temperature BT4 device", "open pressure BT4 device", ... with an even simpler protocol, just a stream of values. But these ways of reading sensor data are not far from reading NMEA.
I know my need to log temperature (and other weather data) along with the track is quite a niche wish, but I'll be happy to help Locus Map enhancement in any way you may think, so don't hesitate to ask.
Thank you.
Jean-Louis
Hello,
I've read some information about commercial devices (mainly boat stuff) and they all provide their data through different NMEA sentences: MTW (Mean Temperature of Water) or XDR. In the later case, the data seems to be quite free which may cause some decoding problems, but it allows a wider choice of data types (in fact any kind of data collected with sensors).
As you probably know, NMEA protocol is closed. So I wasn't able to find any free recent documentation. But I collected some information available on few web sites and forums (afaik gathered by reverse engineering). Here are the more interesting ones:
As Locus Map already provides an interface with some BT4 devices, another way to solve data input problem may be to provide an open interface. You may add a "generic open BT 4 device" in the bluetooth manager with a simple protocol (e.g. a stream of <type>,<value> (maybe P,1000 for pressure,value in millibars or T,22.5 for temperature,value in Celcius)). Or it may be an "open temperature BT4 device", "open pressure BT4 device", ... with an even simpler protocol, just a stream of values. But these ways of reading sensor data are not far from reading NMEA.
I know my need to log temperature (and other weather data) along with the track is quite a niche wish, but I'll be happy to help Locus Map enhancement in any way you may think, so don't hesitate to ask.
Thank you.
Jean-Louis
Good day jlp6k,
thank you for a very useful information. Creating some generic interface is not now too simple. I have in mind change of Bluetooth manager system in Locus to some more flexible system, which should then support custom NMEA messages like this without bigger problems. Unfortunately time is my enemy and I have to choose where to invest it .. and I'm sure you will understand that this, for me very interesting topic, is not something most of users will appreciate in Locus for now.
I've changed your question to idea, so other may votes if interested. Because post is correctly tagged with "bluetooth" tag, I'll for sure find it next year when I believe, work on new BT manager will be done. Thank you for understanding.
Good day jlp6k,
thank you for a very useful information. Creating some generic interface is not now too simple. I have in mind change of Bluetooth manager system in Locus to some more flexible system, which should then support custom NMEA messages like this without bigger problems. Unfortunately time is my enemy and I have to choose where to invest it .. and I'm sure you will understand that this, for me very interesting topic, is not something most of users will appreciate in Locus for now.
I've changed your question to idea, so other may votes if interested. Because post is correctly tagged with "bluetooth" tag, I'll for sure find it next year when I believe, work on new BT manager will be done. Thank you for understanding.
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