CubeCell-GPS-6502 - battery/supercap?

#1

Hey team,

I finally got my new boards, after they travelled backwards and forwards a few times. Such are the times we live in. I will publish a TTN Mapper script for it soon since that’s a good demo app for LoRaWAN mixed in with the gps reading.

In any case, there is an unpopulated square on the board, and looking back at the early production photos shows there was a battery/supercap in that spot. It’s not going to matter much for me, but I’d be interested in knowing why that didn’t turn out to be useful/possible for keeping the ephemeris over deepsleep? Can/should it be retrofitted for some use cases?

Great GPS reception on the onboard antenna too. I would suggest marking the u.fl sockets in a future release too (GPS vs LoRa)

Thanks,
Bruce

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#2

Hi，
At the beginning，we considered a super capacitor which is connect to VDD as the GPS back power for gps rtc module. But finally we cancelled it because the super capacitor works only when there is no battery.

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#3

@bwooce Did you ever by any chnace make progress with the TTN Mapper script? I have one of these boards enroute and looking forward to playing with it. Did you manage to squeeze down the long and lat for your payload ok? Thanks again!

#4

Yeah I’ve got a decent script for it, I wanted to control (alternate) the DR (Spreading Factor) though but the CubeCell overrides what I set with setDR() on transmit and I stalled out before getting it working (anyone solved that?) - it’s stuck on SF7 but that’s what TTNMapper recommend anyway.

It’s using 10 bytes as I put in an extra byte for a satellite count and point-of-interest indicator bit (set by pressing a button). It uses a stupidly small amount of power compared to the ESP32 board it replaces, and has better RF performance too.

The lack of the GPS supercap is occasionally an issue in this use case as I power it down when I’m not using it - it’s taken many minutes to regain full lock sometimes. I will refit a super-cap when they finally arrive, the one I stole from another GPS module improved things a lot on another board.

The code is up on my GitHub, along with the .js decoder for TTN.

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#5

@bwooce - you are a star! Much appreciated!