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gpsgsmat-commandsim-cardnmea
Victor Vargas
Victor Vargas

Reputation: 103

SIM868 GNSS Not outputting the data from AT+CGNSINF command

I've been developing a PCB board with the SIM868. And per the 'SIM868_Series_Hardware_Design_V1.06' I implemented the "All-in-one Mode" All in one Mode

My Schematic is as follow:

SCH Snap

I've been following the GNSS sequence per the 'SIM868_GNSS_Application Note_V1.00' document.

It basically instructs you to follow the AT commands

  1. Turn on GNSS module [AT+CGNSPWR=1]
  2. Set NMEA sentence [AT+CGNSSEQ="RMC"]
  3. Query GNSS info [AT+CGNSINF]

The problem I'm having is that when I request the GNSS info, i get the following output

**+CGNSINF: 0,,,,,,,,,,,,,,,,,,,,** .

The first parameter (Which is GNSS run status] is set always to '0' when it should be '1' since I send the [AT+CGNSPWR=1] first and the module reply correctly [OK reply]. Also the 10k [R49] pull-up is installed between GNSS_EN and GPIO1.

If I look at the trace of GPS_TX [pin 61], I do get the NMEA sentences and the LAT,LON,VEL,UTC etc parameters.

I have measured the UART2_RXD [pin23] and it effectively gets the UART signal from the GNSS module

The FW version of the SIM868 is [1418B02SIM868M32].

Any guess why it fails to request the GNSS info?

Upvotes: 1

Views: 6080

Answers (1)

user9856749
user9856749

Reputation: 1

I have similar pcb design. Had a GNSS problems too. Finally it's working. Have 1 exception in design. I'm not using R49(R101). GNSS_EN is controlled with MCU. Problems was in soldering quality. After resolving this problems - my output is +CGNSINF: 1,,,,,,,,,,,,,,,,,,,, and have a fix in short time.

Upvotes: 0

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