EC-21AU EC-25AU GPS Working then Stop Working - How to flash - we cannot ship our products

IoT Modules LTE Standard Module
1

Hello Quectel

We use EC-21AU LCC and EC-25AU LCC in our product. Usually GPS function works well. Hardware design is same as Quectel App note.

Sometimes at unpredictable time the EC-21AU or EC-25AU in our product will fail and not return latitude and longitude. This seems to happen when power cycles. After this fail reset cannot fix.

At the moment we have EC-21AU and EC-25AU built on our product. But cannot return latitude and longitude.(Usually always is OK).

We would like the tools to try to flash both parts with newest firmware to try to fix. We use LCC version so if we cannot flash and fix we need to discard which is expensive.

Please help. Thank you,

Tony

Further test results:
NMEA GPGSV query fails. But but 4 remaining NMEA queries respond, but data is blank. In a loop we test all NMEA sentences below. But GSV sentence no response. In the code loop below we request all 5 NMEA GPS sentences. 4 response but are blank. GPGSV no response (this is the blank line in the loop).

$GPGSA,A,1,1E
$GPVTG,T,M,N,K,N2C
$GPGGA,0,66
$GPRMC,V,N53

$GPGSA,A,1,1E
$GPVTG,T,M,N,K,N2C
$GPGGA,0,66
$GPRMC,V,N53

$GPGSA,A,1,1E
$GPVTG,T,M,N,K,N2C
$GPGGA,0,66
$GPRMC,V,N53

2

Hi @tonyrichardson
The problem you are talking about is that nmea statements occasionally appear, but there is no location information, right? Can you tell me the specific model, because there are many branches of these two models, and it would be better if you could tell me the version you are currently using.

3

Hi Lyman,
Thank you for your reply. So far we fixed the problem. It seems to be signal strength. If GPS signal is too low when we query GPGSV we get no response. But other NMEA strings DO respond. However they have no data. We doubled gain in our external GPS antenna and problem is fixed. GPGSV responds OK.
Tony.