LC86GLA does not output NMEA frames

IoT Modules GNSS Module
1

I’m starting to work with LC86GLA and I’m now testing 3 units.

After a few days, one of the units stopped sending NMEA frames (RMC, GGA, etc.), it only outputs the following information during its initialization (when turned on):

[Bootloader] bl_uart_init done
set CP10 and CP11 Full Access
[CLK] Dynamic Clock Management: Enable
[CLK] frequency meter
CM4(CMSYS) freq [215974]KHz
BUS(FSYS) freq [107974]KHz
SFC freq [107974]KHz
SPISLV freq [0]KHz
I3C freq [108000]KHz
RTC SRAM freq [107974]KHz
hal_flash_init
BL Jump to addr 0x8009000 (0)
$PQTMVER,1,MODULE,LC86GLANR12A02S,2023/12/26,09:53:00*11

I had tried to send $PAIR007 to reset the module to its factory default settings but still same behaviour and no NMEA frames.

I would really appreciate any comments on what the problem and root cause of this unit’s failure could be, as I am now evaluating Quectel GNSS LC86GLA to be used in series production for a project.
Tks!

2

btw, as additional informantion, when I sent $PAIR0073D to the module I got the following response: $PAIR001,007,23E

but according to its manual, the correct response should be: $PAIR001,007,0*3C

Not sure if this is the case, but this response number “2” I got means error code “Failed execution” for PQTM Messages.

3

Did you find a solution to this as I have the same problem, devices work for 2-3 weeks and then one by one they all start to enter this state

4

Hi @system123

Thank you for reaching out

May i know is the Firmware upgrade done by using QGNSS?

I will send you the latest firmware for upgrade, please check your email and let me know if you have received it

Best regards,

5

I will try the firmware update, but why does this happen in the first place?

6

Hi @system123

May i know how do you supply power to the VCC and VBCKP?

You can try send the following command to verify if NMEA message is output
$PAIR002*38

Best regards,

7

VCC is supplied from the same 3.3V supplying my ESP32 (Lilygo T-SIM7000)
VBCKP is connected to an MS621FE rechargable 3V cell
The input power is using a DC-DC converter with TVS that takes 12V to 5V which then goes into the Lilygo LDO and power circuitry.

All PAIR commands do not get ACK, so there is no effect. The device tries to JL from bootloader and there afer reboots as if the watchdog triggered it.

There can be cases when the power turns off suddenly (as it is connected to a vehicle). The device ran fine (roughly running 9-10 hrs a day) for about 2 weeks and then between week 2 and 3 we saw multiple devices fail in the same way. This was also a period of increases solar activity.

8

Hi @system123

Are you able to check the voltage fluctuation for both VCC and VBCKP? The recommended allowable voltage fluctuation should be kept below 50 mV.

if possible, can you check the power up sequence and the minimum voltage being supply to the device

img_v3_02uo_044f638f-c7f3-47eb-b0a7-4986baea66ix
img_v3_02uo_044f638f-c7f3-47eb-b0a7-4986baea66ix666×213 11.3 KB

best regards,

9

Unfortunately I cannot monitor that in the field, but the DCDC power supply we are using has less than 50mV ripple at 3.3V