I don’t know man, with 3MB per hour, if i have a 256GB card in it, that’s 85k+ hours that I can log, that’s 9.7 years of non stop logging. 
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Actually it’s not that. Its to do with how GPS works and if you want to read more about it, the search term you would use is GPS TTFF (which stands for Time To First Fix)
A GPS device can have 3 states
Cold - From factory or hasn’t been powered up for a long time. The receiver must find 1 satellite and then from this it can get the data about the other satellites, this data is called the almanac and is transmitted continuously every 12.5 mins and is valid for 180 days. TTFF is around 15 - 20 mins
Warm - was powered up recently and has the “almanac” now it just needs to get the ephemeris data (details of satellite orbital characteristics) this ephemeris data is valid for 4 hours
Hot - was powered really recently and already has ephemeris data and the almanac so fix is super fast.
Sorry for the derail, but that’s why the first time you turn it on it takes a while to get a fix. What @hexakopter is saying is it can take even longer if you have it buried somewhere.
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The maximum is 32 gb because that’s what FAT32 filesystem supports. But you don’t have to think about it because SD card is included with Metr Pro CAN + SD module. Even with 16 gb it is overkill anyway.
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hot damn, that’s a nice touch. now i just need to put my other metr into my boards, so i can get the can version
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Anybody in the US get their Metr Can order? Mine seems to be stuck between Germany and the US since Dec 23rd
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Nope my Metr is stuck in limbo as well 
Fucking Covid
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Is it just the metr can ones? I just got a metr a week or 2 ago
Edit: ordered Jan 1 received Jan 19
Metr can for me that I ordered back in Nov 22.
To @kilow, @ProfoundMagician and everyone else that got their Metr Pro orders shipped out in December 2020.
I checked the tracking numbers and it looks like all the packages haven’t reached the US yet. The shipping company states that transport capacities to the US are reduced because of Covid-19 and some packages are shipped to the US via ocean freight.
I am guessing that December shipments were send via ocean freight and January ones via airfreight. That would explain why some January 2021 orders are already delivered and all December ones haven’t reached the US yet.
I am very sorry for these long delays, but their isn’t anything we can do at the moment to speed up delivery, because it is completely in the hands of the shipping company. Because packages to Australia also took longer, but reached their destination now, I am hoping its the same for US packages in the near future.
I will regularly check some US tracking numbers and let you know when the first ones reach the US.
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No worries, I’m pretty slow getting all my stuff put together anyway.
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Blockquote Yes you can. A tool would be required for decoding the format, but we can fix that.
Is there any news on this tool? I’d love to get access to the full log file as well
What is the use case? Are you recording very long sessions? If they are below 1 hour, you already get very good resolution
It’s to analyze data of a delivery vehicle, the sessions could be up to 10 hours. It could be used for days on end without any uploads so it would be nicest to be able to ‘drag and drop’ a bunch of files at the same time
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I am quite busy right now with other things, but I can spend an hour just to help you with format documentation. On how to decode the binary file from SD card, something like this:
| byte count | payload |
|---|---|
| 1 | file version |
| 8 | unix time (ms) |
| N | compressed data |
Compressed data uses LZS algorithm and is just a sequence of packets in format that VESC uses
| byte count | payload |
|---|---|
| 1 | start marker, usually 2 or 3 |
| 1-2 | packet length |
| N | data |
| 2 | crc16 |
| 1 | end marker, usually 3 |
But you probably want a tool that can display files from SD card similar to what metr.at does, right? Or in other format? Does the tool have to operate locally? Would you be up to create this tool on your own? Or maybe sponsor the development?
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Just curious, why it uses a different format than the json from the app?
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JSON format takes more space which makes transfer via BLE really painful. Although easy to read, current JSON format does not support easy adding of new data by just writing to the end of the file. Keeping structures in memory, modifying different parts of the file would be necessary, which would be a bad choice for continuous logging and limited resources available on nRF52
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I’ll be analyzing the data with a Python script/other language so I don’t necessarily need the beautiful graphs and overlays of Metr.at. Also since you’re busy right now, I’ll give the decoding a shot and see if I run into issues. Thanks for the formatting info!
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mine just showed up with torn packaging, in a bag the post office re-packaged it in.
So what app uses the GPS so far? does the metr app have a new version or something?
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Just the regular metr app.
Connect metr to vesc, gps module to metr, connect metr to phone and boom it detects the external GPS (even shows you)
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