Thanks for the feedback @CycloMies!
Great to hear that battery life is so good! Is it two days with the LilyGO ESP32 board and the 18650 battery? (Still waiting for my board to arrive to check myself).
Re. additional buttons: I can see them useful on the ground, but not when flying… What is the use case for additional buttons you are proposing?
If you are to build a new board, you might want it to be as versatile as possible. Good boards tend to get more users, and thereby better support (incl. pre-built device code).
User buttons are to easy the use of the device UI. Currently only one button sets tight restrictions on how users can interact with the device (only press, long press, double press…). We might want features, like to be able to report our status (on the ground, on an airplane, leaving the plane…), answer easy yes/no questions, or to set the settings of the device. To do this, a couple buttons would easy the process.
Regarding to battery life, @geeksville have shared a sheet on google drive with proper calculations. There are also lots of real life tests reported on this forum. However, sorry to say, I couldn’t find the links for you. 
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Thanks, this makes sense. I also cannot find the spreadsheet you mention.
oh yes - paragliding was one of the main usecases I’d eventually like to see this project widely used for (I’m a now lapsed formerly very active P4 pilot). If you do make a board, possibly work together with corvus. Also consider stuffing a BMP280 so it could work as a mesh enabled vario - so that all pilots in an area could share a dynamic auto-built lift map of the thermals.
Paragliding is almost an ideal case because each radio has GREAT line of sight, so in most cases forwarding packets isn’t even needed (and power levels can be low and speed can be set high). If someone lands out, any radio in the air will ‘magically’ route their packets to everyone else. So that all users have a current and last known position map for all pilots. Which is useful for retrieves and for safety/accidents.
(I’ve only skimmed this great thread - but if I’ve missed anything I can help comment on I"m happy to do so)
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We would also love to bring this to the world of powered paragliding someday soon. Im one of the co-founders of openppg.com and currently working on an nrf52 based board (currently just focused on BLE and not mesh, yet).
We’re a small but well connected team in the flying world and happy to help figure out ways to tie this in to our open source electric flying machines!
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@geeksville I saw references to ttgo eink nrf52 board in the github, what is the status of this project? Is the board available for purchase?
they are not. I just received a new rev of the board (to fix minor problems in the previous rev - which I’ll get to after some stuff for @syed’s board). I suspect they are close to shipping (but I don’t know, but this board looks ‘close or done’). It will probably take me 2-3 days to get it going.
Wow, very cool project! I always wanted to try PPG but was afraid of noisy gas engines :). With this, I have no excuse :).
Lets discuss paragliding-specific stuff on a separate thread?
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I have a couple of the ISP4520 modules, I just haven’t made a PCB for them yet! They are incredibly small.
When I first looked at the datasheet they had graphed a really good S11 figure of -42dB for a 40mmx50mm board size which is what I was going to target. They have subsequently released an application note that revises that to -3.8dB! I queried them on this and they said:
Thank you so much for your remark. We would like to highlight that curves in the app note and from the datasheet are both the result of simulations. We started to corelate these values with some tests on our module engineering batches, but we are definitely waiting our first production lots to get more data and calculate statistical values to be published in our documents.
So I would say it needs a few real life product examples to test their range.
Yes, I am working on a 40x50 mm ISP4520 board, will see the results once it is ready. Please, post any data you get meanwhile.
On my board I plan to provide a connector for an optional external antenna, in case the internal one is not good. But then the benefits of this miniature board with external antenna are not clear, as compared to nrf52 module + Lora module.
Yea I am more inclined to go for a EByte E22 module with a small external antenna as it also has a higher (claimed) receive sensitivity.
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Ebyte E104-BT5040U vs. E73
- more pins available,
- same pins spacing,
- USB connector,
- enclosure,
- 2 buttons,
- 2 LEDs (1 single color + 1 RGB),
- 32.768 kHz crystal,
- LEDs and push button mapping is compatible with PCA10059 (Nordic nRF52840 Dongle)
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Before going to the bother of building a board, I’d love some help getting this one working
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