Latest UBLOX GPS modules have a feature that's not yet activated from factory but can be unlocked within a couple of minutes. I have an instant 3D GPS fix every time I plug in my battery or let's say within 10-30 seconds, you should get 10 to 20 sats within 2 minutes.
What you need:
- Download Ucenter2 https://www.u-blox.com/en/u-center-2
- Make an account for AssistNow https://www.u-blox.com/en/product/assistnow
- Apply for the AssistNow token (which you'll receive per email)
Work with caution and at your own risk! I'm not responsible for bricked modules!
This enhancement will lock baudrate to 115200 and 10hz update frequency between FC and GPS module. Second part adds an Almanac that tells your GPS what sats it's supposed to see (predicted data) instead of blindly searching for sats.
1. Connect USB cable and battery (for GPS power) and open up the Betaflight Configurator and confirm that the correct UART (Port) is activated for GPS (remember the UART number for later) and select baudrate 115200 if not already selected. (Don't forget cooling for your VTX while the battery is connected !)
2. Go to CLI and enter "serialpassthrough 3 115200". Most iFlight BNFs have the GPS module installed on UART4(-1 to address the serial address) = 3, that's why 3 and not 4.
3. Some cryptic stuff should appear, not sure why but it does. If it doesn't, start all over again by disconnecting battery and USB cable, close and open up again the Configurator.
4. Cryptic stuff there? Then close the Betaflight Configurator and open up Ucenter2. Click on "Add device" and select the only STM device available. Leave auto bauding on for now.
5. Click on Device Configuration and then "Import" on the left.
6. Download and select the Configuration file from https://drive.google.com/file/d/1G0_jd9WnVG30PEvGIsJL6wtevVywxZuS/view?usp=share_link
7. Click on Send. Green checkmarks should run down the commands on the right.
8. Since your GPS module is supposed to change baudrate and I'm not sure if during the process everything was successfully stored, we now close the Configuration window and click on "Add Device" again but this time select a manual baudrate of 115200.
9. Your GPS should be connected again. If that's not the case then repeat step 2-4 but and reconnect it. Remember to use the baudrate 115200 instead of auto bauding this time.
10. GPS should be connected again with the status "receiving data". We now repeat step 7 and send all settings again. We close the Device Configuration Window. So far we've setup our GPS to run at 10hz and baudrate 115200.
11. Now there comes the magic. Click on the tool icon and AssistNow Offline.
12. Click on Default server (it pulls an URL by itself) and copy paste your token from the email you received, then hit Save settings.
13. Select every available checkbox option, leave the rest at the default and click on Download from server. This small file should just take a second. Scroll down and hit Transfer with reset and aiding (Host).
ATTENTION: You'll get 7 days of data but your GPS will also further update the Almanac while flying. You can also select 35 days if you don't regularly fly. Since this is an offline Almanac you'll either need to fly or keep updating it in intervals to enhance the GPS cold start speed.
14. Wait for it to finish. Click on close and select "Flash" this time, then hit Transfer again.
15. Finished. If you want to know what AssistNow is doing, please go and checkout the ublox documentation. Your GPS is now setup with 10hz, 115200 baud rate and has an Almanac installed for instant cold start GPS fix.
Thank me later.