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GSM UART GNSS

Application Note

GSM/GPRS Module Series

Rev. GSM_UART_GNSS_Application_Note_V3.0

Date: 2013-08-16

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GSM/GPRS Module GSM UART GNSS Application Note

GSM_UART_GNSS_Application_Note Confidential / Released 1 / 13

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About the document

History

Revision Date Author Description

3.0 2013-08-16 Bob DENG/Ray XU Initial

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Contents

About the document ................................................................................................................................... 2

Contents ....................................................................................................................................................... 3

Table Index ................................................................................................................................................... 4

Figure Index ................................................................................................................................................. 5

1 Introduction .......................................................................................................................................... 6

2 Description ........................................................................................................................................... 7

2.1. AT Command Syntax ............................................................................................................... 7

2.2. Description of AT Command .................................................................................................... 7

2.2.1. AT+QGPSRD Read GPS Data ..................................................................................... 7

2.2.2. AT+QGPSCFG GPS Configuration ............................................................................... 9

2.2.3. AT+QGPSCMD Send NMEA Commands Defined by Manufacturers ........................ 10

2.3. Hardware Connection ............................................................................................................ 11

3 Appendix A Reference ....................................................................................................................... 13

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Table Index

TABLE 1: RELATED DOCUMENTS .................................................................................................................. 13

TABLE 2: TERMS AND ABBREVIATIONS ........................................................................................................ 13

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Figure Index

FIGURE 1: REFERENCE DESIGN FOR IDENTICAL LEVEL .......................................................................... 12

FIGURE 2: REFERENCE DESIGN FOR DIFFERENT LEVEL ......................................................................... 12

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1 Introduction

This document mainly introduces how to use the UART GPS function of Quectel module. With this

solution, MCU can get the GPS data from the module’s main UART by AT commands.

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2 Description

2.1. AT Command Syntax

Test Command AT+<x>=? This command returns the list of parameters and value ranges

set by the corresponding Write Command or internal processes.

Read Command AT+<x>? This command returns the currently set value of the parameter

or parameters.

Write Command AT+<x>=<…> This command sets the user-definable parameter values.

Execution

Command AT+<x>

This command reads non-variable parameters affected by

internal processes in the GSM engine

2.2. Description of AT Command

2.2.1. AT+QGPSRD Read GPS Data

Get a variety of standard GPS NMEA data.

AT+QGPSRD Read GPS Data

Test Command

AT+QGPSRD=?

Response

+QGPSRD:

(“NMEA/GGA”,”NMEA/GLL”,”NMEA/GSA”,”NMEA/GSV”,”N

MEA/RMC”,”NMEA/VTG”,”NMEA/ZDA”)

OK

Read Command

AT+QGPSRD?

Response

+QGPSRD: “NMEA/GGA”

+QGPSRD: “NMEA/GLL”

+QGPSRD: “NMEA/GSA”

+QGPSRD: “NMEA/GSV”

+QGPSRD: “NMEA/RMC”

+QGPSRD: “NMEA/VTG”

+QGPSRD: “NMEA/ZDA”

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Parameters

Example

AT+QGPSRD=? //Test mode.

+QGPSRD:

(“NMEA/GGA”,”NMEA/GLL”,”NMEA/GSA”,”NMEA/GSV”,”NMEA/RMC”,”NMEA/VTG”,”NMEA/ZDA

”)

OK

AT+QGPSRD? //Query the current parameter values.

+QGPSCFG: “NMEA/GGA”

+QGPSCFG: “NMEA/GLL”

+QGPSCFG: “NMEA/GSA”

+QGPSCFG: “NMEA/GSV”

+QGPSCFG: “NMEA/RMC”

+QGPSCFG: “NMEA/VTG”

+QGPSCFG: “NMEA/ZDA”

OK

AT+QGPSRD=”NMEA/GGA” //Query GGA NMEA sentence.

+QGPSRD: $GPGGA…..,

OK

AT+QGPSRD=”NMEA/GLL” //Query GLL NMEA sentence.

OK

Write Command

AT+ QGPSRD=<type>

Response

+QGPSRD: <NMEA Format Data>

OK

ERROR

Reference

<type> String parameter type, indicates the value of <type>.

“NMEA/GGA”

“NMEA/GLL”

“NMEA/GSA”

“NMEA/GSV”

“NMEA/RMC”

“NMEA/VTG”

“NMEA/ZDA”

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+QGPSRD: $GPGLL…..,

OK

2.2.2. AT+QGPSCFG GPS Configuration

Parameters

1. Parameters will be automatically saved into NVRAM after they are configured successfully. This

command can be saved by AT&W.

2. If the module has three serial ports, it is recommended to use UART3 to connect GPS engines, or

use UART2 to connect GPS engines.

3. UART2 is also named as DBG_UART.

AT+QGPSCFG GPS Configuration

Test Command

AT+QGPSCFG=?

Response

+QGPSCFG: <type>,<value>

OK

Read Command

AT+QGPSCFG?

Response

+QGPSCFG: “GPSPORT”,”UART2”

+QGPSCFG: “GPSBAUD”,9600

+QGPSCFG: “GPSINIT”,0

OK

Write Command

AT+ QGPSCFG=<type>[,<value>]

Response

OK

ERROR

Reference

<type> String parameter type indicates the configuration parameter type.

“GPSPORT”

“GPSBAUD”

“GPSINIT”

<value> For different <type>, the <value> is shown as below::

If <type> is “GPSPORT”, <value> is “UART2” or “UART3”.

If <type> is “GPSBAUD”, <value> is baud rate such as 115200,57600,19200,9600,4800.

NOTES

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Example

AT+QGPSCFG=? //Test mode.

+QGPSCFG: <type>,<value>

OK

AT+QGPSCFG? //Query the current parameter values.

+QGPSCFG: “GPSPORT”,”UART2”

+QGPSCFG: “GPSBAUD”,”9600”

+QGPSCFG: “GPSINIT”,0

OK

AT+QGPSCFG=”GPSPORT”,2 //Select the module’s UART2 port to receive GPS data.

OK

AT+QGPSCFG=”GPSBAUD”,9600 //Set the baud rate of the UART2 port to 9600 to receive GPS

data.

OK

2.2.3. AT+QGPSCMD Send NMEA Commands Defined by Manufacturers

Parameters

AT+QGPSCMD Send NMEA Commands Defined by Manufacturers

Test Command

AT+QGPSCMD=?

Response

+QGPCMD: <cmd_str>

OK

Read Command

AT+QGPSCMD?

Response

+QGPCMD: <cmd response>

OK

Write Command

AT+ QGPSCMD=<cmd_str>

Response

OK

ERROR

Reference

<cmd_str> String parameter type indicates NMEA private commands defined by manufacturers.

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Example

AT+QGPSCMD=? //Test command.

+QGPCMD: <cmd_str>

OK

AT+QGPSCFG=”GPSINIT”,1 //GPS function initialized.

OK

AT+QGPSCFG=”GPSPORT”,”UART2” //Set GSM module’s UART2 to receive GPS data.

OK

AT+QGPSCFG=”GPSBAUD”,9600 //Set baud rate of UART port to 9600 to receive GPS

data.

OK

AT+QGPSCMD="$PMTK314,1,1,1,1,1,5,0,0,0,0,0,0,0,0,0,0,0,1,0*2D" //Send GPS NMEA private

command defined by MTK.

OK

AT+QGPSCMD? //Query the response of the command mentioned above.

+QGPSCMD: $PMTK001,314,3*36 //$PMTK001,314,3*36 is the response to above MTK

private NMEA command.

OK

AT+QGPSCFG=”GPSINIT”,0 //Turn off the GPS function.

OK

2.3. Hardware Connection

I/O level of all Quectel GSM modules is 2.8V. GPS/GNSS modules have two types of I/O level: 1.8V and

2.8V. You can get the I/O electric characteristics of UART from the document of Hardware Design. The

hardware connection between Quectel GSM modules and GPS/GNSS receiver is illustrated as below.

If GSM module has the similar I/O level with GPS/GNSS module. A 1K resistor is recommended to insert

between GSM module and GPS module for a better communication performance. It would be fine if GSM

and GPS/GNSS module are connected directly.

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GSM module

RXD

TXD

TXD

RXD

GPS/GNSS

Module1K

1K

GNDGND

Figure 1: Reference Design for Identical Level

If the GSM and GPS module have different level respectively (1.8V and 2.8V), a level shift is employed.

The following picture shows the combination of resistor and transistor forming a level shift.

GSM module

TXD

RXD

1.8V

4.7K

VDD_EXT 4.7K

2K

TXD

RXD

GND

GPS/GNSS

module1K

GND

Figure 2: Reference Design for Different Level

1. VDD_EXT is the output voltage of GSM module. It is 2.8V voltage level.

2. Since GSM and GPS/GNSS module may have their own UART name, so all the name of UARTs are

unified as TXD and RXD.

NOTES

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3 Appendix A Reference

Table 1: Related Documents

SN Document name Remark

[1] NMEA-0183 standard

Table 2: Terms and Abbreviations

Abbreviation Description

NMEA National Marine Electronics Association

GNSS Global Navigation Satellite System.

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