BLE Serial for RTK Express?

GPS/GNSS
1

I’d like to be able to use BLE Serial on my RTK Express so that I can use my web app on Android. I looked at the firmware for both RTK Surveyor and RTK Everywhere and see that BLE serial is supported in the newer firmware. The Bluetooth.ino interfaces that each uses are very similar.

I’ve compiled the stock RTK Surveyor firmware, but I’ve not yet risked bricking my Express. I’m wondering if a SparkFun engineer could comment on the likely hood of getting the Surveyor working on esp32@3.0.7 with the newer BLE support?

Specifically,

You tried to upgrade the Express firmware but hit road blocks?
You did not try because these are older products and time marches on?
You did not try, but know of hard blockers?

Is it likely that if I’ve built the firmware successfully then I can load it with out bricking my RTK Express?

Thanks, John

2

Hi John,

Congrats on compiling from source. It’s no small task and you are one of a select few!

You cannot brick an ESP32 via the serial bootloader. I’ve done many mean things to many ESP32s and they are always recoverable (at least from a software perspective). You will always be able to re-flash production firmware to bring your Express back to original operation.

You are welcome to tailor RTK Firmware to work on ESP32 Arduino v3.x core. The main limiter is RAM. RTK Surveyor Firmware (RTK Express, Surveyor, Facet, etc) assumed 0 PSRAM, whereas RTK Everywhere can add additional features because we have more RAM on those platforms (RTK Torch, EVK, Postcard, etc all have external PSRAM of a few MB or more). Internally we talked about handicapping some features in order to add others to RTK Surveyor Firmware but it just got too complicated (hence we broke from RTK Surveyor firmware to RTK Everywhere). If you’re savvy, you can remove some features (I dunno, WiFi) and upgrade the core to v3.x. I will say the ESP32 Arduino v3.x core does take more RAM just at a basic compilation level. I have seen the various libraries (WiFi and BT are the big offenders) take more RAM in v3.x.

Best of luck and please let us know what you changed/added. Perhaps we can add some of that to RTK Everywhere.

2 Likes
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Thanks for encouragement. We’ll see how far I get.

I’m wondering about POINTPERFECT_TOKEN? If the necessary to enable the chip or just to use the uBlox network service?

J

4

You can compile without it. That’s our magic token. It’s just for PointPerfect provisioning (Facet L-Bad).

1 Like
5

Uggh - The Express dropped the serial line after one or two blocks of the firmware were loaded and now won’t enumerate on the USB. I don’t see a reset button inside.

Ideas?

Thanks. J

6

I was pulling my hair out yesterday, trying different cables, checking that other devices would enumerate and looking for other ways to reset the esp32. Anyway, after leaving the Express unplugged over night and trying yet another cable - This morning everything looks OK and I’ve flashed the stock firmware. AND I flashed my own build. Yeah!

Very strange, but all is well.

J

7

You had me scratching my head as well! Good to hear everything is back to normal.