BG951A-GL GNSS Application Notes Clarifications

IoT Modules LPWA Module
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1

Hello,

I have 3 questions about the BG951A-GL. I have been having extreme difficulties getting consistent results from the chip. I am using a BG951AGLTEB-KIT for testing and development.

First 2 questions relate to the Quectel_BG77xA-GL&BG95xA-GL_GNSS_Application_Note_V1.2 document:

Question 1:
In section 2.3.1.18. AT+QGPSCFG=“gnss_mode” Select GNSS Mode there are 2 notes. The second one reads:

  1. BG951A-GL module supports this command only over the main AT port when
    AT+QGPSCFG=“gnss_mode”,1.

I do not understand what this means. It is effectively saying that the command only works when the command setting is currently 1. However the default value is 0 so then it should never work, and in my experience the command still functions when set to 0 or 2.

This is an important question as I am having very unpredictable behaviour from the module, and understanding when this command actually works is crucial. I wondered if the note was meant to specify that it only works under a specific setting of AT+QGPSCFG="outport".

Question 2:
In section 2.3.2. AT+QGPS Turn on GNSS there is a parameter <GNSS_mode>.

This is the first parameter in the write command (<GNSS_state> is for the read command only). The only setting is 1: “Stand-alone mode” but I don’t know what this is. All models BG95x have this as well as the original BG95, so it cannot be related to AT+QGPSCFG=“gnss_mode”,2 setting which makes the BG951 be controlled from the GNSS Uart independent of the modem / main AT Port. So what does this mean / refer to?

Question 3:
I was speaking to somebody about my these difficulties. They told me the module can have inconsistent behaviour if it is not powered down in a specific way. They said they were told over the phone by Quectel a specific way to shut it down to ensure al caches are saved and discarded correctly.

How do I correctly power down the module and the GNSS. And how do I power it down if the GNSS Uart stops responding (or GNSS commands stop responding over main AT port; meaning internally the GNSS MCU isnt responding)?

I know this is a long post, but I really appreciate any help you can provide me.

Best Regards,
Max

2

Hi @Max_Holstegge

A1:
[ When you set AT+QGPSCFG=“gnss_mode”,1, GNSS communicating over MAIN_UART port.
for AT+QGPSCFG=“gnss_mode”,2. GNSS AT commands should be sent over external GNSS_UART port.]

A2:
Stand-alone mode means there is on realying any external auxiliary information(e.g AGPS,XTRA…)

A3:
For the power down, please take reference with BG951A-GL HD