The project I’m developing is described in this thread L85 GPS problem.
I currently use the L86 GPS module with the AXN_5.1.9_3333 firmware and I encountered the following problem:
After the L86 performs the position FIX, if i remove and reconnect power (the V_BCKP remains powered by a 3.3V battery),L86 takes more than 30sec to redo the FIX (
AXN5.1.9_Log2.pdf (184.6 KB)
AXN5.1.9_Log1.pdf (107.7 KB)
after many tests I found that the problem occurs when the position fix interval (set using $PMTK220) is less than 1sec (i work with 100mSec)
The problem does not depend on the board (I did the same tests with the GNSS-L8X-EVB_2.2 evaluation board) but on the firmware version installed in the L86,
in fact with the AXN_3.21_3333 or AXN_5.1.6 FIX is executed in less than 3 sec (
AXN5.1.6_Log2.pdf (63.4 KB)
AXN5.1.6_Log1.pdf (66.7 KB)
Is there any firmware or configuration update that allows me to overcome this big problem?
I’m not sure about the envirnoment where you test. From the log you provided, the number of satellite in view is about 4~6. That means the signal level is very low. So the module have chance to get fixed slower.
I don’t have GSV and GSA sentences for further confirmation. If you can enable them, please provide me with new log. Thanks.
I did the tests in the same conditions, same external antenna placed in same position, same board (GNSS-L8X-EVB_2.2 QUECTEL evaluation board) using 2 GPS module with AXN5.1.6 and AXN5.1.9 firmware respectively.
The logs were made within a few minutes of each other, as you can see the number of satellites is almost the same in all log, the only difference is that AXN5.1.6 sees 6 satellites and fixes in less than 5 sec (AXN5.1.6_Log2 and AXN5.1.6_Log1), while AXN5.1.9 when fixes, after 30sec or more, sees only 4 or 5 (AXN5.1.9_Log1 and AXN5.1.9_Log2), it doesn’t seem normal to me.
I would add one thing regarding the number of satellites, I noticed a certain degradation in the number of satellites that the GPS can see, between firmware version, as I reported in the discussion L85 GPS problem.
I don’t understand why in the same conditions the most recent firmwares have lower performance than the older ones.
Regarding the addition of the GSV and GSA sentences, i am unable to provide the other logs at this time, but I would need an answer based on the existing information.
Please help confirm the firmware version of the EVBs by sending $PQVERNO,R*3F
How likely is this problem to reappear?
With AXN5.1.9 the problem appears systematically
I will send you latest L86 firmware via message.
I suggest you adding AGNSS function to your device. It needs to download EPO files from AGNSS server. EPO (Extended Prediction Orbit) is an AGNSS feature provided by the chipset supplier, which can improve sensitivity and shorten TTFF (time to first fix).
I tried the firmware you sent me, it behaves like L86NR03A01S and therefore does not solve the problem.
I don’t understand why I have to use AGNSS, when the datasheet says:
“The V_BCKP pin supplies power for RTC domain. It should be valid when powering on the module. The
voltage of RTC domain ranges from 2 V to 4.3 V. In order to achieve a better TTFF, RTC domain should
be valid all the time. It can supply power for SRAM memory in RTC domain which contains all the
necessary GNSS information for quick start-up and a small amount of user configuration variables.”
Why does the L86 work as described in the datasheet if I set the position fix interval to 1 sec while if I set it to 100mS it doesn’t?