[IOT] BDS/GNSS Full Constellation Positioning and Navigation Module–ATGM332D-5N

With the continuous progress of technology, navigation systems have become an indispensable part of our daily life. Traditional navigation systems often only provide basic maps and route planning, which is not enough to meet some special needs or personalized positioning.Full Constellation Positioning and Navigation ModuleThe emergence of the navigation module brings us a brand new navigation experience. By combining the doctrine of astrology and personal traits, this navigation module can provide users with more personalized positioning services, so that everyone can find the most suitable road and direction for themselves. In this article, we will explore the principles, functions and advantages of the All Constellation Positioning Navigation Module, bringing you a journey of discovery about the future of navigation systems.

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I. Functional description

1.1 General

ATGM332D-5N series modules are 12X16 size high-performance BDS/GNSS full constellation positioning and navigation modules. These modules are based on the fourth generation of low-power GNSS SOC single-chip – the ATGM332D-5N series.AT6558It supports a wide range of satellite navigation systems, including China’sBDS(Beidou satellite navigation system), the United StatesGPSRussia’sGLONASSThe EU’sGALILEOJapaneseQZSS and satellite-based augmentation systemsSBAS（WAAS，EGNOS，GAGAN，MSASThe AT6558 is a true six-in-one multimode satellite navigation and positioning chip with 32 tracking channels that can simultaneously receive GNSS signals from six satellite navigation systems and realize joint positioning, navigation and timing.

ATGM332D-5N series modules have the advantages of high sensitivity, low power consumption, low cost, etc. They are suitable for in-vehicle navigation, handheld positioning, wearable devices, and can directly replace Ublox NEO series modules.

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1.2 Performance indicators

• Excellent positioning and navigation functions, supporting single-system positioning of BDS/GPS/GLONASS satellite navigation systems, as well as any combination of multi-system joint positioning, and supporting QZSS and SBAS systems.
• Support for A-GNSS
• Cold-start capture sensitivity:-148dBm
• Tracking sensitivity:-162dBm
• Positioning accuracy:2.5 meters（CEP50）
• Time of first orientation:32 sec.
• Low power consumption: continuous operation<25mA（@3.3V）
• Built-in antenna detection and antenna short circuit protection

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1.3 Module Functional Block Diagram

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1.4 Areas of application

• Vehicle Positioning and Navigation
• Cell phones, tablets, handheld devices
• Embedded Positioning Devices
• wearable

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1.5 Assisted GNSS (AGNSS)

The ATGM332D-5N series modules all support the Auxiliary GNSS (AGNSS) function, which provides the receiver with auxiliary information necessary for positioning, such as messages, rough position and time. This information can significantly reduce the time to first fix in both strong and weak signal environments.

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1.6 Output protocols

ATGM332D-5N series modules are available through theUART As the main output channel, follow theNMEA0183 The protocol format of the output.

UART Portal:【IoT】 Read the UART communication protocol in one article

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1.7 FLASH

ATGM331C-5N Series ModulesEquipped with FlashIt is possible to update the positioning functions and algorithms through the online upgrade function. This configuration function allows customers to configure the positioning update rate independently to obtain the applicable low power consumption; it allows customers to be updated with the latest optimization progress of global multimode positioning; it allows customers to add new control functions, such as positioning records, regular geo-fencing, and customized output formats.

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1.8 Antennas

ATGM332D-5N series modules supportactive antennawithpassive antenna。

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1.9 Upstream tools

CCM provides theGNSSToolKitThe Lite version of the package (Windows Version,Android version) for locating output parsing and operating mode configuration.
CCM provides theUBF Serial Upgrade ToolThe software package (Windows The PC-based online upgrade tool is available for PC-based versions. The device-based online upgrade program has to be developed by the customer.

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II. Technical description

2.1 PIN Ranking Chart

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2.2 Pin Definitions

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2.3 Electrical parameters

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2.4 Technical specifications

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2.5 Module Application Circuitry

2.5.1 Active antenna application program (antenna power supply, antenna detection and short-circuit protection are provided inside the module)

2.5.2 Passive Antenna Application Scenarios (Adding a LNA to the RF_IN input of the module)

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2.6 Notes on Module Usage

• Low-ripple LDO power supplies are used to keep ripple within 50mVpp.
• Try not to run other high frequency and high amplitude digital signals near the module. It is better to fill all underneath the module with ground wires.
• The antenna connector is located as close as possible to the module’s RF input pins, with attention to 50-ohm impedance matching.
• The module itself has active antenna access, unplugging, short circuit detection circuit, and at the same time, when the antenna is accidentally short-circuited, the antenna’s power supply current will be limited (50mA), which serves as a protective function. When the status of the above three antenna ports changes, corresponding information can be output from the serial port. For example

$GPTXT,01,01,01,ANTENNA SHORT*63 
$GPTXT,01,01,01,ANTENNA OPEN*25 
$GPTXT,01,01,01,ANTENNA OK*35

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2.7 Electrostatic protection:

The ATGM332D-5N module series are electrostatic sensitive devices. Frequent electrostatic contact can lead to accidental damage to the modules. In addition to the standard electrostatic protection requirements, the following points should be followed as much as possible:

1. The first position of the contact module should be PCB GND unless PCB GND is already well grounded.
2. When connecting the antenna, connect GND first and then the signal cable.
3. When touching the RF part of the circuit, do not touch the charging capacitor and keep away from devices and equipment that can generate static electricity, such as dielectric antennas, coaxial wires, soldering irons, etc.
4. To avoid charge discharge through the RF input, do not touch the exposed portion of the antenna dielectric. For cases where contact with the exposed antenna media may occur, anti-static protection circuitry needs to be added to the design.
5. When soldering connectors, antennas connected to the RF input, be sure to use a static-free soldering gun.

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III. Module development

3.1 Module Connection Cables

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3.2 Installation of drivers

After connecting the cable, install the driver for the ch340 and the serial number appears.

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3.3 Data parsing

The best test is to bring the computer to the open space outdoors, if the antenna is placed outside the balcony, there is a certain chance of positioning failure, which is affected by the distance between the building, the obstruction and other factors. The first time positioning in open space is usually within one minute. The LED on the board keeps flashing at a certain frequency to prove that the positioning is successful, we use the serial port to look at the data, the baud rate is defaulted to9600。

After successful positioning, the data is displayed on the serial port:

$GNGGA,084852.000,2236.9453,N,11408.4790,E,1,05,3.1,89.7,M,0.0,M,,*48
$GNGLL,2236.9453,N,11408.4790,E,084852.000,A,A*4C
$GPGSA,A,3,10,18,31,,,,,,,,,,6.3,3.1,5.4*3E
$BDGSA,A,3,06,07,,,,,,,,,,,6.3,3.1,5.4*24
$GPGSV,3,1,09,10,78,325,24,12,36,064,,14,26,307,,18,67,146,27*71
$GPGSV,3,2,09,21,15,188,,24,13,043,,25,55,119,,31,36,247,30*7F
$GPGSV,3,3,09,32,42,334,*43
$BDGSV,1,1,02,06,68,055,27,07,82,211,31*6A
$GNRMC,084852.000,A,2236.9453,N,11408.4790,E,0.53,292.44,141216,,,A*75
$GNVTG,292.44,T,,M,0.53,N,0.98,K,A*2D
$GNZDA,084852.000,14,12,2016,00,00*48
$GPTXT,01,01,01,ANTENNA OK*35

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Let’s interpret the data step by step
Inside the data, we see three types of data.GN、GP、BD on behalf ofdual mode、GPS mode、Big Dipper mode。

NMEA0183 Protocol The contents of the frame format can be found in the following tables:

(1) $GPGGA (GPS Positioning Information)

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(2) $GPGLL (geo-positioning information)

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(3)$GPGSA (current satellite information)

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(4) $GPGSV (visible satellite information)

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(5) $GPRMC (minimal positioning information)

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(6) $GPVTG (ground speed information)

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(7) Antenna status output

$GPTXT,01,01,01,ANTENNA OK*35

Ok means the antenna has been detected, open means the antenna is disconnected.

Calculation of UTC time and current Beijing time

$GNGGA,084852.000,2236.9453,N,11408.4790,E,1,05,3.1,89.7,M,0.0,M,,*48

What you see is the UTC time in the format hhmmss.sss, with three decimal seconds ignored, which would be 08:48:52.

UTC + time zone difference = local time

The time zone difference is positive in the east and negative in the west. In this case, the time zone difference between the eight eastern zones is recorded as +08, so the Beijing time is 16:48:5. Conversion of latitude and longitude

Concerning the conversion of latitude and longitude

$GNRMC,084852.000,A,2236.9453,N,11408.4790,E,0.53,292.44,141216,,,A*75

Data format: Degree score format converted to Baidu Google Map format.
Latitude: ddmm.mmmm North 2236.9453 22+(36.9453/60)= 22.615755
Longitude: dddmm.mmmm East 11408.4790 114+(08.4790/60)=114.141317

If you want to convert it to degrees, minutes, and seconds.
North 2236.9453 = 22 degrees 36 minutes 0.9453×60 seconds = 22 degrees 36 minutes 56.718 seconds
Longitude 11408.4790 = 114 degrees 8 minutes 0.4790×60 seconds = 114 degrees 8 minutes 28.74 seconds

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IV. Hot start Warm start Cold start

cold startIt is the process of starting a GPS in an unfamiliar environment until the GPS makes contact with the surrounding satellites and calculates the coordinates. The following conditions are considered to becold start：

• For initial use;
• When battery depletion causes loss of ephemeris information;
• Move the receiver over a distance of 1000 kilometers with the power off.

That is to say, the cold start is a mandatory start through the hardware way, because the distance from the last operation of the GPS has been cleared out of the internal positioning information, GPS receivers lose satellite parameters, or the parameters that already existed and the actual reception of the satellite parameters are too different, resulting in the navigator can not work, you must be from the new satellite to provide the coordinates of the data, so that the vehicle from the basement to start the navigation is 100% counted as a cold start, so that the vehicle from the basement start navigation. This is also the reason why it takes a long time to search for stars from the basement.

warm startIt refers to the startup more than 2 hours from the last positioning time, and the time of searching and positioning is between cold start and warm start. If you have used GPS positioning on the previous day, the first startup on the next day is a warm startup, and the last position information will be displayed after the startup. Because the latitude, longitude and altitude before the last shutdown are known, but due to the long shutdown time, the ephemeris has been changed, the previous satellites can not be received, a number of satellites in the parameter have lost contact with the GPS receiver, and it is necessary to continue to search for satellites to supplement the position information, so the time of searching for satellites is longer than the warm start and shorter than the cold start.

hot startIt refers to the startup of GPS without much movement from the last shutdown place, but the time from the last positioning must be less than 2 hours, and the startup after some preparations such as saving and shutting down before startup by means of software.