NMEA 0183 (ASCII) Protocol

For simple use, the Inertial Sense device supports a human-readable NMEA communications protocol based on NMEA 0183. The NMEA protocol is human readable from in a command line terminal but is less optimal than the binary protocol in terms of message length for the same amount of data.

Communications Examples

The NMEA Communications Example Project demonstrates how to implement the protocol.

Packet Structure

The Inertial Sense NMEA protocol follows the standard NMEA 0183 message structure:

• 1 byte – Start packet, $ (0x24)
• n bytes – packet identifier
• 1 byte – comma (0x2C)
• n bytes – comma separated list of data, can include decimals and text
• 1 byte – checksum marker, * (0x2A)
• 2 bytes – checksum in hex format (i.e. f5 or 0a), 0 padded and lowercase
• 2 bytes – End packet, \r\n (0x0D, 0x0A)

The packet checksum is an 8 bit integer and is calculated by calculating the exclusive OR of all bytes in between and not including the $ and * bytes. The packet checksum byte is converted to a 2 byte NMEA hex code, and left padded with 0 if necessary to ensure that it is always 2 bytes. The checksum is always lowercase hexadecimal characters. See NMEA 0183 message structure for more details. The NMEA string checksum is automatically computed and appended to string when using the InertialSense SDK serialPortWriteAscii function or can be generated using an online checksum calculator. For example: MTK NMEA checksum calculator

Persistent Messages

The persistent messages option saves the current data stream configuration to flash memory for use following reboot, eliminating the need to re-enable messages following a reset or power cycle.

• To save current NMEA persistent messages - send the $PERS command.
• To disable persistent messages - send $STPB](#stpb) followed by [$PERS.

Binary persistent messages are also available.

Enabling Persistent Messages - EvalTool

To enable persistent NMEA messages using the EvalTool:

• Enable the desired NMEA messages in the EvalTool "Data Sets" tab. Select DID_NMEA_BCAST_PERIOD in the DID menu and set the desired NMEA messages period to a non-zero value.
• Press the "Save Persistent" button in the EvalTool "Data Logs" tab to store the current message configuration to flash memory.
• Reset the IMX and verify the messages are automatically streaming. You can use a generic serial port program like putty or the EvalTool->Data Logs->Data Log->Messages dialog to view the NMEA messages.

To disable all persistent messages using the EvalTool, click the "Stop Streaming" button and then "Save Persistent" button.

NMEA Input Messages

The following NMEA messages can be received by the IMX.

Message	Description
$ASCE*14\r\n	Query the broadcast rate of NMEA output messages.
ASCE	Set the broadcast period of selected NMEA output messages.
$INFO*0E\r\n	Query device information.
$SRST*06\r\n	Software reset.
$PERS*14\r\n	Save persistent messages to flash.
$STPB*15\r\n	Stop broadcast of all messages (NMEA and binary) on all ports.
$STPC*14\r\n	Stop broadcast of all messages (NMEA and binary) on current port.

ASCE

Enable NMEA message output streaming by specifying the NMEA message identifier or ID and broadcast period. The period is the multiple of the data source period (i.e. a GNSS message with period multiple of 2 and data source period of 200 ms (5 Hz) will broadcast every 400 ms). “xx” is the two-character checksum. A period of 0 will disable message streaming. The broadcast period for each message is configurable as a period multiple of the Data Source Update Rates. Up to 20 different NMEA messages can be enabled by repeating the message ID and period sequence within an ASCE message.

$ASCE,OPTIONS,(ID,PERIOD)*xx\r\n

The following examples will enable the same NMEA message output:

$ASCE,0,PPIMU,1,PINS2,10,GNGGA,1*26\r\n
$ASCE,0,2,1,5,10,7,1*39\r\n

Index	Field	Description
1	OPTIONS	Port selection. Combine by adding options together: 0=current, 1=ser0, 2=ser1, 4=ser2, 8=USB, 512=persistent (remember after reset)
		Start of repeated group (1...20 times)
2+n*2	ID	Either 1.) message identifier string (i.e. PPIMU, PINS1, GNGGA) excluding packet start character $ or 2.) message ID (eNmeaAsciiMsgId) of the NMEA message to be streamed. See the message ID in the NMEA output messages table.
3+n*2	PERIOD	Broadcast period multiple for specified message. Zero disables streaming.
		End of repeated group (1...20 times)

Example Messages

The following examples NMEA messages enable IMX data streaming output. The data period is 1, full data source rates, for those that do not specify the output rate.

Message	Data (Output Rate)**
$ASCE,0,6,1,7,1,8,1,10,1,14,1*04\r\n	GGA, GLL, GSA, ZDA, GSV (all at 5Hz)
$ASCE,0,5,2,2,1,7,1*0A\r\n	PINS2 (31.25 Hz), PPIMU (62.5Hz), GGA (5Hz)
$ASCE,0,0,1*09\r\n	PIMU
$ASCE,0,1,1*08\r\n	PPIMU
$ASCE,0,2,1*0B\r\n	PRIMU
$ASCE,0,3,1*0A\r\n	PINS1
$ASCE,0,4,1*0D\r\n	PINS2
$ASCE,0,5,1*0C\r\n	PGPSP
$ASCE,0,6,1*0F\r\n	GGA
$ASCE,0,7,1*0E\r\n	GLL
$ASCE,0,8,1*01\r\n	GSA
$ASCE,0,9,1*00\r\n	RMC
$ASCE,0,10,1*38\r\n	ZDA
$ASCE,0,11,1*39\r\n	PASHR
$ASCE,0,12,1*3A\r\n	PSTRB
$ASCE,0,13,1*3B\r\n	INFO
$ASCE,0,14,1*3C\r\n	GSV
$ASCE,0,15,1*3D\r\n	VTG

^** These rates assume the default settings for data source rates.

PERS

Send this command to save current persistent messages to flash memory for use following reboot. This eliminates the need to re-enable messages following a reset or power cycle. In order to disable persistent messages, all messages must be disabled and then the 'save persistent messages' command should be sent.

$PERS*14\r\n

STPB

Stop all broadcasts (both binary and NMEA) on all ports by sending the following packet:

$STPB*15\r\n

The hexadecimal equivalent is:

24 53 54 50 42 2A 31 35 0D 0A

STPC

Stop all broadcasts (both binary and NMEA) on the current port by sending the following packet:

$STPC*14\r\n

The hexadecimal equivalent is:

24 53 54 50 43 2A 31 34 0D 0A

NMEA Output Messages

The following NMEA messages can be sent by the IMX. The message ID (eNmeaAsciiMsgId) is used with the $ASCE message to enable message streaming.

Identifier	ID	Description
ASCB		Broadcast period of NMEA output messages.
PIMU	1	IMU data (3-axis gyros and accelerometers) in the body frame.
PPIMU	2	Preintegrated IMU: delta theta (rad) and delta velocity (m/s).
PRIMU	3	Raw IMU data (3-axis gyros and accelerometers) in the body frame.
PINS1	4	INS output: euler rotation w/ respect to NED, NED position from reference LLA.
PINS2	5	INS output: quaternion rotation w/ respect to NED, ellipsoid altitude.
PGPSP	6	GPS position data.
GGA	7	Standard NMEA GGA GPS 3D location, fix, and accuracy.
GLL	8	Standard NMEA GLL GPS 2D location and time.
GSA	9	Standard NMEA GSA GPS DOP and active satellites.
RMC	10	Standard NMEA RMC Recommended minimum specific GPS/Transit data.
ZDA	11	Standard NMEA ZDA UTC Time/Date message.
PASHR	12	Standard NMEA PASHR (euler) message.
PSTRB	13	Strobe event input time.
INFO	14	Device information.
GSV	15	Standard NMEA GSV satellite info (all active constellations sent with corresponding talker IDs).
VTG	16	Standard NMEA VTG track made good and speed over ground.

The field codes used in the message descriptions are: lf = double, f = float, d = int.

PIMU

IMU sensor data (3-axis gyros and accelerometers) in the body frame.

$PIMU,lf,f,f,f,f,f,f*xx\r\n
       1 2 3 4 5 6 7

Index	Field	Units	Description
1	time	sec	Time since system power up
3	IMU pqr[0]	rad/sec	IMU angular rate gyro – X
2	IMU pqr[1]	rad/sec	IMU angular rate gyro – Y
4	IMU pqr[2]	rad/sec	IMU angular rate gyro – Z
5	IMU acc[0]	m/s2	IMU linear acceleration – X
6	IMU acc[1]	m/s2	IMU linear acceleration – Y
7	IMU acc[2]	m/s2	IMU linear acceleration – Z

PPIMU

Preintegrated inertial measurement unit (IMU) sensor data, delta theta in radians and delta velocity in m/s in the body frame. Also known as coning and sculling integrals.

$PPIMU,lf,f,f,f,f,f,f,f*xx\r\n
        1 2 3 4 5 6 7 8

Index	Field	Units	Description
1	time	sec	Time since system power up
2	theta[0]	rad	IMU delta theta integral – X
3	theta[1]	rad	IMU delta theta integral – Y
4	theta[2]	rad	IMU delta theta integral – Z
8	vel[0]	m/s	IMU delta velocity integral – X
9	vel[1]	m/s	IMU delta velocity integral – Y
10	vel[2]	m/s	IMU delta velocity integral – Z
14	dt	s	Integration period for delta theta vel

PRIMU

Raw IMU sensor data (3-axis gyros and accelerometers) in the body frame (up to 1KHz). Use this IMU data for output data rates faster than DID_FLASH_CONFIG.startupNavDtMs. Otherwise we recommend use of PIMU or PPIMU as they are oversampled and contain less noise. 0 to disable.

$PRIMU,lf,f,f,f,f,f,f*xx\r\n
        1 2 3 4 5 6 7

Index	Field	Units	Description
1	time	sec	Time since system power up
3	Raw IMU pqr[0]	rad/sec	Raw IMU angular rate gyro – X
2	Raw IMU pqr[1]	rad/sec	Raw IMU angular rate gyro – Y
4	Raw IMU pqr[2]	rad/sec	Raw IMU angular rate gyro – Z
5	Raw IMU acc[0]	m/s2	Raw IMU linear acceleration – X
6	Raw IMU acc[1]	m/s2	Raw IMU linear acceleration – Y
7	Raw IMU acc[2]	m/s2	Raw IMU linear acceleration – Z

PINS1

INS output with Euler angles and NED offset from the reference LLA.

$PINS1,lf,d,d,d,f,f,f,f,f,f,lf,lf,lf,f,f,f*xx\r\n
        1 2 3 4 5 6 7 8 9 0  1  2  3 4 5 6

Index	Field	Units	Description
1	timeOfWeek	sec	Seconds since Sunday morning in GMT
2	GPS week	weeks	Number of weeks since January 1st of 1980 in GMT
3	insStatus		INS Status Flags
4	hdwStatus		Hardware Status Flags
5	theta[0]	rad	Euler angle – roll
6	theta[1]	rad	Euler angle – pitch
7	theta[2]	rad	Euler angle – yaw
8	UVW[0]	m/s	Velocity in body frame – X
9	UVW[1]	m/s	Velocity in body frame – Y
10	UVW[2]	m/s	Velocity in body frame – Z
11	Latitude	deg	WGS84 Latitude
12	Longitude	deg	WGS84 Longitude
13	HAE Altitude	m	Height above ellipsoid (vertical elevation)
14	NED[0]	m	Offset from reference LLA – North
15	NED[1]	m	Offset from reference LLA – East
16	NED[2]	m	Offset from reference LLA – Down

PINS2

INS output with quaternion attitude.

$PINS2,lf,d,d,d,f,f,f,f,f,f,f,lf,lf,lf*xx\r\n
        1 2 3 4 5 6 7 8 9 0 1  2  3  4

Index	Field	Units	Description
1	timeOfWeek	sec	Seconds since Sunday morning in GMT
2	GPS week	weeks	Number of weeks since January 1st of 1980 in GMT
3	insStatus		INS Status Flags
4	hdwStatus		Hardware Status Flags
5	qn2b[0]		Quaternion rotation (NED to body) – W
6	qn2b[1]		Quaternion rotation (NED to body) – X
7	qn2b[2]		Quaternion rotation (NED to body) – Y
8	qn2b[3]		Quaternion rotation (NED to body) – Z
9	UVW[0]	m/s	Velocity in body frame – X
10	UVW[1]	m/s	Velocity in body frame – Y
11	UVW[2]	m/s	Velocity in body frame – Z
12	Latitude	deg	WGS84 Latitude
13	Longitude	deg	WGS84 Longitude
14	HAE altitude	m	Height above ellipsoid (vertical elevation)

PGPSP

GPS navigation data.

$PGPSP,d,d,d,lf,lf,lf,f,f,f,f,f,f,f,f,f,f*xx\r\n
       1 2 3  4  5  6 7 8 9 0 1 2 3 4 5 6

$PGPSP,337272200,2031,1075643160,40.33057800,-111.72581630,1406.39,1425.18,0.95,0.37,0.55,-0.02,0.02,-0.03,0.17,39.5,337182.4521*4d\r\n

Index	Field	Units	Description
1	timeOfWeekMs	ms	GPS time of week in milliseconds since Sunday morning in GMT
2	GPS week	weeks	GPS number of weeks since January 1st of 1980 in GMT
3	status		(see eGpsStatus) GPS status: [0x000000xx] number of satellites used, [0x0000xx00] fix type, [0x00xx0000] status flags
4	Latitude	deg	WGS84 Latitude
5	Longitude	deg	WGS84 Longitude
6	HAE altitude	m	Height above WGS84 ellipsoid
7	MSL altitude	m	Elevation above mean sea level
8	pDOP	m	Position dilution of precision
9	hAcc	m	Horizontal accuracy
10	vAcc	m	Vertical accuracy
11	Velocity X	m/s	ECEF X velocity
12	Velocity Y	m/s	ECEF Y velocity
13	Velocity Z	m/s	ECEF Z velocity
14	sAcc	m/s	Speed accuracy
15	cnoMean	dBHz	Average of all satellite carrier to noise ratios (signal strengths) that non-zero
16	towOffset	s	Time sync offset between local time since boot up to GPS time of week in seconds. Add this to IMU and sensor time to get GPS time of week in seconds.
17	leapS	s	GPS leap second (GPS-UTC) offset. Receiver's best knowledge of the leap seconds offset from UTC to GPS time. Subtract from GPS time of week to get UTC time of week.

GGA

NMEA GPS fix, 3D location and accuracy data.

$GPGGA,204153.200,4003.34331,N,11139.51872,W,1,25,0.93,1433.997,M,18.82,M,,*6d\r\n
                1          2 3           4 5 6  7    8     9    0     1 2 3 4

Index	Field	Units	Description	Example
1	HHMMSS.sss		UTC time (fix taken at 20:41:53.200 UTC)	204153.200
2,3	Latitude	deg,min	WGS84 latitude (DDmm.mmmmm,N)	4003.34331,N
4,5	Longitude	deg,min	WGS84 longitude (DDDmm.mmmmm,E)	11139.51872,W
6	Fix quality		0 = invalid, 1 = GPS fix (SPS), 2 = DGPS fix, 3 = PPS fix, 4 = RTK Fix, 5 = RTK Float, 6 = estimated (dead reckoning), 7 = Manual input mode, 8 = Simulation mode	1
7	# Satellites		Number of satellites in use	15
8	hDop	m	Horizontal dilution of precision	0.9
9,10	MSL_altitude	m	Elevation above mean sea level (MSL)	545.4,M
11,12	Undulation	m	Undulation of geoid. Height of the geoid above the WGS84 ellipsoid.	46.9,M
13	empty	s	Time since last DGPS update
14	empty		DGPS station ID number

GLL

NMEA geographic position, latitude / longitude and time.

$GPGLL,4916.45123,N,12311.12324,W,225444.800,A*33\r\n
                1 2           3 4          5 6

Index	Field	Units	Description	Example
1,2	Latitude	deg,min	WGS84 latitude (DDmm.mmmmm,N)	4916.45123,N
3,4	Longitude	deg,min	WGS84 longitude (DDDmm.mmmmm,E)	12311.12324,W
5	HHMMSS.sss		UTC time (fix taken at 22:54:44.8 UTC)	225444.800
6	Valid		Data valid (A=active, V=void)	A

GSA

NMEA GPS DOP and active satellites.

$GPGSA,A,3,04,05,,09,12,,,24,,,,,2.5,1.3,2.1*39\r\n
       1 2  3  4 ...              15  16  17

Index	Field	Units	Description	Example
1			Auto selection of 2D or 3D fix (M = manual)	A
2	Fix quality		Fix quality (1 = none, 2 = 2D, 3 = 3D)	3
3-14	Sat ID		Satellite ID (PRNs)	04,05,,09,12,,,24,,,,,
15	pDop	m	Dilution of precision	2.5
16	hDop	m	Horizontal dilution of precision	1.3
17	vDop	m	Vertical dilution of precision	2.1

RMC

NMEA GPS recommended minimum specific GPS/Transit data.

eg1. $GPRMC,081836,A,3751.65,S,14507.36,E,000.0,360.0,130998,011.3,E*62\r\n
eg2. $GPRMC,225446,A,4916.45,N,12311.12,W,000.5,054.7,191194,020.3,E*68\r\n

           225446       Time of fix 22:54:46 UTC
           A            Navigation receiver warning A = OK, V = warning
           4916.45,N    Latitude 49 deg. 16.45 min North
           12311.12,W   Longitude 123 deg. 11.12 min West
           000.5        Speed over ground, Knots
           054.7        Course Made Good, True
           191194       Date of fix  19 November 1994
           020.3,E      Magnetic variation 20.3 deg East
           *68          mandatory checksum

eg3. $GPRMC,220516,A,5133.82,N,00042.24,W,173.8,231.8,130694,004.2,W*70\r\n
              1    2    3    4    5     6    7    8      9     10  11 12

      1   220516     Time Stamp
      2   A          validity - A-ok, V-invalid
      3   5133.82    current Latitude
      4   N          North/South
      5   00042.24   current Longitude
      6   W          East/West
      7   173.8      Speed in knots
      8   231.8      True course
      9   130694     Date Stamp
      10  004.2      Variation
      11  W          East/West
      12  *70        checksum

eg4. $GPRMC,hhmmss.ss,A,llll.ll,a,yyyyy.yy,a,x.x,x.x,ddmmyy,x.x,a*hh\r\n
1    = UTC of position fix
2    = Data status (V=navigation receiver warning)
3    = Latitude of fix
4    = N or S
5    = Longitude of fix
6    = E or W
7    = Speed over ground in knots
8    = Track made good in degrees True
9    = UT date
10   = Magnetic variation degrees (Easterly var. subtracts from true course)
11   = E or W
12   = Checksum

VTG

NMEA GPS track made good and speed over ground.

eg1. $GPVTG,140.88,T,,M,8.04,N,14.89,K,D*05\r\n

0   Message ID $GPVTG
1   Track made good (degrees true)
2   T: track made good is relative to true north
3   Track made good (degrees magnetic)
4   M: track made good is relative to magnetic north
5   Speed, in knots
6   N: speed is measured in knots
7   Speed over ground in kilometers/hour (kph)
8   K: speed over ground is measured in kph
9   Mode indicator:
        A: Autonomous mode
        D: Differential mode
        E: Estimated (dead reckoning) mode
        M: Manual Input mode
        S: Simulator mode
        N: Data not valid
10  The checksum data, always begins with *

ZDA

NMEA GPS UTC Time and Date specification.

$GPZDA,213301.200,31,08,2023,00,00*41\r\n
                1  2  3    4  5  6

Index	Field	Units	Description	Example
1	HHMMSS.sss		UTC Time	213301.200
2	Day		Day	31
3	Month		Month	08
4	Year		Year	2023
5	localHrs		Local time zone hours	00
6	localMin		Local time zone minutes	00

GSV

NMEA GNSS satellites in view. xx corresponds to a constellation talker ID, shown in the table below.

Contains the number of sats in view, PRN numbers, elevation, azimuth and SNR value. Each message includes up to four satellites. When there are more than 4 sats for a constellation, multiple messages are sent. The total number of messages and the message number are included in each message.

Example:

$GPGSV,6,1,23,02,40,310,43,08,07,324,31,10,48,267,45,15,37,053,45*7C\r\n
$GPGSV,6,2,23,16,12,268,35,18,69,078,41,23,74,336,40,24,15,111,37*79\r\n
$GPGSV,6,3,23,26,02,239,31,27,35,307,38,29,12,162,37,32,14,199,39*7B\r\n
$GPGSV,6,4,23,44,43,188,43,46,40,206,43,522,48,267,45,527,37,053,26*73\r\n
$GPGSV,6,5,23,530,69,078,34,535,74,336,34,536,15,111,25,538,02,239,18*74\r\n
$GPGSV,6,6,23,539,35,307,27,541,12,162,21,544,14,199,25*73\r\n
$GAGSV,2,1,08,05,65,144,41,09,39,052,43,34,71,341,42,36,46,105,39*6A\r\n
$GAGSV,2,2,08,517,65,144,30,521,39,052,30,546,71,341,27,548,46,105,30*64\r\n
$GBGSV,3,1,10,11,09,141,34,14,52,047,44,27,32,313,43,28,80,263,44*64\r\n
$GBGSV,3,2,10,33,81,039,43,41,43,230,42,43,33,148,42,58,,,44*5B\r\n
$GBGSV,3,3,10,11,09,141,16,14,52,047,32*60\r\n
$GQGSV,1,1,01,02,45,101,30*49\r\n
$GLGSV,2,1,07,65,85,260,33,66,28,217,30,72,36,034,35,81,20,324,33*69\r\n
$GLGSV,2,2,07,87,47,127,35,88,73,350,34,87,47,127,20*53\r\n

Example NMEA version 4.11:

$GPGSV,4,1,14,02,40,310,43,08,07,324,31,10,48,267,45,15,37,053,45,1*67\r\n
$GPGSV,4,2,14,16,12,268,35,18,69,078,41,23,74,336,40,24,15,111,37,1*62\r\n
$GPGSV,4,3,14,26,02,239,31,27,35,307,38,29,12,162,37,32,14,199,39,1*60\r\n
$GPGSV,4,4,14,44,43,188,43,46,40,206,43,1*65\r\n
$GPGSV,3,1,09,10,48,267,45,15,37,053,26,18,69,078,34,23,74,336,34,6*68\r\n
$GPGSV,3,2,09,24,15,111,25,26,02,239,18,27,35,307,27,29,12,162,21,6*64\r\n
$GPGSV,3,3,09,32,14,199,25,6*58\r\n
$GAGSV,1,1,04,05,65,144,41,09,39,052,43,34,71,341,42,36,46,105,39,7*7E\r\n
$GAGSV,1,1,04,05,65,144,30,09,39,052,30,34,71,341,27,36,46,105,30,2*73\r\n
$GBGSV,2,1,08,11,09,141,34,14,52,047,44,27,32,313,43,28,80,263,44,1*71\r\n
$GBGSV,2,2,08,33,81,039,43,41,43,230,42,43,33,148,42,58,,,44,1*4E\r\n
$GBGSV,1,1,02,11,09,141,16,14,52,047,32,B*0D\r\n
$GQGSV,1,1,01,02,45,101,30,1*54\r\n
$GLGSV,2,1,06,65,85,260,33,66,28,217,30,72,36,034,35,81,20,324,33,1*75\r\n
$GLGSV,2,2,06,87,47,127,35,88,73,350,34,1*75\r\n
$GLGSV,1,1,01,87,47,127,20,3*41\r\n

Talker ID	Constellation
GP	GPS
GQ	QZSS
GA	Galileo
GL	Glonass
GB	BeiDou
GN	Combination of active constellations

Index	Field	Units	Description
1	numMsgs		Total number of messages for this constellation and epoch
2	msgNum		Message number
3	numSats		Total number of known satellites for the talker ID and signal ID
4+(n*5)	prn		Satellite PRN number
5+(n*5)	elev	deg	Elevation (0-90)
6+(n*5)	azim	deg	Azimuth (000 to 359)
7+(n*5)	snr	dB	SNR (00-99, empty when not tracking)
variable	system ID		GNSS system ID (distinguishes frequency band). This field is only output if the NMEA version is 4.11.

Where n is 0-3, for the four satellites supported by this message.

GSV Output Filtering

Verbosity and size of the GSV NMEA message can be reduced to only select constellation and frequencies by using a Filtered GSV NMEA Message IDs instead of the standard GSV message ID GPGSV or 15 (NMEA_MSG_ID_GNGSV), either ASCII or integer. Note that the GSV output filter can only hide or mask information for satellites currently enabled in the DID_FLASH_CONFIG.gnssSatSigConst satellite system constellation. Usage:

$ASCE,[options],[Message ID]*[checksum]\r\n

For example, using message ID GPGSV_1 or 3857 (NMEA_MSG_ID_GPGSV_1) will output only the GPS L1 frequency and prevent all other frequency and constellation satellite information from being displayed.

$ASCE,0,GPGSV_1,2*01\r\n
$ASCE,0,3857,2*33\r\n

Filtered GSV NMEA Message IDs

The following extended GSV NMEA message IDs are defined in data_sets.h.

All Constellations	Message ID ASCII	Message ID Int	Description
NMEA_MSG_ID_GNGSV_0	GNGSV_0	3840	Clear all constellations and frequencies
NMEA_MSG_ID_GNGSV_1	GNGSV_1	3841	Enable all constellations band1
NMEA_MSG_ID_GNGSV_2	GNGSV_2	3842	Enable all constellations band2
NMEA_MSG_ID_GNGSV_2_1	GNGSV_2_1	3843	Enable all constellations band1, band2
NMEA_MSG_ID_GNGSV_3	GNGSV_3	3844	Enable all constellations band3
NMEA_MSG_ID_GNGSV_3_1	GNGSV_3_1	3845	Enable all constellations band1, band3
NMEA_MSG_ID_GNGSV_3_2	GNGSV_3_2	3846	Enable all constellations band2, band3
NMEA_MSG_ID_GNGSV_3_2_1	GNGSV_3_2_1	3847	Enable all constellations band1, band2, band3
NMEA_MSG_ID_GNGSV_5	GNGSV_5	3848	Enable all constellations band5
NMEA_MSG_ID_GNGSV_5_1	GNGSV_5_1	3849	Enable all constellations band1, band5
NMEA_MSG_ID_GNGSV_5_2	GNGSV_5_2	3850	Enable all constellations band2, band5
NMEA_MSG_ID_GNGSV_5_2_1	GNGSV_5_2_1	3851	Enable all constellations band1, band2, band5
NMEA_MSG_ID_GNGSV_5_3	GNGSV_5_3	3852	Enable all constellations band3, band5
NMEA_MSG_ID_GNGSV_5_3_1	GNGSV_5_3_1	3853	Enable all constellations band1, band3, band5
NMEA_MSG_ID_GNGSV_5_3_2	GNGSV_5_3_2	3854	Enable all constellations band2, band3, band5
NMEA_MSG_ID_GNGSV_5_3_2_1	GNGSV_5_3_2_1	3855	Enable all constellations band1, band2, band3, band5

GPGSV - GPS	Message ID ASCII	Message ID Int	Description
NMEA_MSG_ID_GPGSV_0	GPGSV_0	3856	Disable all GPS frequencies
NMEA_MSG_ID_GPGSV_1	GPGSV_1	3857	Enable GPS L1
NMEA_MSG_ID_GPGSV_2	GPGSV_2	3858	Enable GPS L2
NMEA_MSG_ID_GPGSV_2_1	GPGSV_2_1	3859	Enable GPS L1, L2
NMEA_MSG_ID_GPGSV_5	GPGSV_5	3864	Enable GPS L5
NMEA_MSG_ID_GPGSV_5_1	GPGSV_5_1	3865	Enable GPS L1, L5
NMEA_MSG_ID_GPGSV_5_2	GPGSV_5_2	3866	Enable GPS L2, L5
NMEA_MSG_ID_GPGSV_5_2_1	GPGSV_5_2_1	3867	Enable GPS L1, L2, L5
NMEA_MSG_ID_GPGSV	GPGSV	3871	Enable all GPS frequencies

GAGSV - Galileo	Message ID ASCII	Message ID Int	Description
NMEA_MSG_ID_GAGSV_0	GAGSV_0	3888	Disable all Galileo frequencies
NMEA_MSG_ID_GAGSV_1	GAGSV_1	3889	Enable Galileo E1
NMEA_MSG_ID_GAGSV_5	GAGSV_5	3896	Enable Galileo E5
NMEA_MSG_ID_GAGSV_5_1	GAGSV_5_1	3897	Enable Galileo E1, E5
NMEA_MSG_ID_GAGSV	GAGSV	3903	Enable all Galileo frequencies

GBGSV - Beido	Message ID ASCII	Message ID Int	Description
NMEA_MSG_ID_GBGSV_0	GBGSV_0	3904	Disable all Beidou frequencies
NMEA_MSG_ID_GBGSV_1	GBGSV_1	3905	Enable Beidou B1
NMEA_MSG_ID_GBGSV_2	GBGSV_2	3906	Enable Beidou B2
NMEA_MSG_ID_GBGSV_2_1	GBGSV_2_1	3907	Enable Beidou B1, B2
NMEA_MSG_ID_GBGSV_3	GBGSV_3	3908	Enable Beidou B3
NMEA_MSG_ID_GBGSV_3_1	GBGSV_3_1	3909	Enable Beidou B1, B3
NMEA_MSG_ID_GBGSV_3_2	GBGSV_3_2	3910	Enable Beidou B2, B3
NMEA_MSG_ID_GBGSV_3_2_1	GBGSV_3_2_1	3911	Enable Beidou B1, B2, B3
NMEA_MSG_ID_GBGSV	GBGSV	3919	Enable all Beidou frequencies

GQGSV - QZSS	Message ID ASCII	Message ID Int	Description
NMEA_MSG_ID_GQGSV_0	GQGSV_0	3920	Disable all QZSS frequencies
NMEA_MSG_ID_GQGSV_1	GQGSV_1	3921	Enable QZSS L1
NMEA_MSG_ID_GQGSV_2	GQGSV_2	3922	Enable QZSS L2
NMEA_MSG_ID_GQGSV_2_1	GQGSV_2_1	3923	Enable QZSS L1, L2
NMEA_MSG_ID_GQGSV_5	GQGSV_5	3928	Enable QZSS L5
NMEA_MSG_ID_GQGSV_5_1	GQGSV_5_1	3929	Enable QZSS L1, L5
NMEA_MSG_ID_GQGSV_5_2	GQGSV_5_2	3930	Enable QZSS L2, L5
NMEA_MSG_ID_GQGSV_5_2_1	GQGSV_5_2_1	3931	Enable QZSS L1, L2, L5
NMEA_MSG_ID_GQGSV	GQGSV	3935	Enable all QZSS frequencies

GLGSV - Glonass	Message ID ASCII	Message ID Int	Description
NMEA_MSG_ID_GLGSV_0	GLGSV_0	3936	Disable all Glonass frequencies
NMEA_MSG_ID_GLGSV_1	GLGSV_1	3937	Enable Glonass L1
NMEA_MSG_ID_GLGSV_2	GLGSV_2	3938	Enable Glonass L2
NMEA_MSG_ID_GLGSV_2_1	GLGSV_2_1	3939	Enable Glonass L1, L2
NMEA_MSG_ID_GLGSV_3	GLGSV_3	3940	Enable Glonass L3
NMEA_MSG_ID_GLGSV_3_1	GLGSV_3_1	3941	Enable Glonass L1, L3
NMEA_MSG_ID_GLGSV_3_2	GLGSV_3_2	3942	Enable Glonass L2, L3
NMEA_MSG_ID_GLGSV_3_2_1	GLGSV_3_2_1	3943	Enable Glonass L1, L2, L3
NMEA_MSG_ID_GLGSV	GLGSV	3951	Enable all Glonass frequencies

VTG

NMEA GPS track made good and speed over ground.

$GPVTG,140.88,T,,M,8.04,N,14.89,K,D*05\r\n
            1 2 3 4   5 6     7 8 9

| Index | Field | Units | Description | Example | |-------|--------|-------|----------------------------------------------------|---------| | 1 | track true | deg | Ground track heading (true north) | 140.88 | | 2 | T | | Ground track heading is relative to true north | T | | 3 | track mag | deg | Ground track heading (magnetic north) | | | 4 | M | | Ground track heading is relative to magnetic north (track mag = track true + magVarCorrection) | M | | 5 | speed Kn | knots | Speed | 8.04 | | 6 | N | | Speed is measured in knots | N | | 7 | speed Km | kph | Speed over ground in kilometers/hour | 14.89 | | 8 | K | | Speed over ground is measured in kph | K | | 9 | mode ind | | Mode indicator: | D | | | | | A: Autonomous mode | | | | | | D: Differential mode | | | | | | E: Estimated (dead reckoning) mode | | | | | | M: Manual Input mode | | | | | | S: Simulator mode | | | | | | N: Data not valid | |

PASHR

NMEA GPS DOP and active satellites.

$PASHR,001924.600,95.81,T,+0.60,+1.05,+0.00,0.038,0.035,0.526,0,0*08\r\n
          1         2   3   4      5    6    7      8     9  10 11  

Index	Field	Units	Description	Example
1	Time		UTC Time	001924.600
2	Heading		Heading value in decimal degrees	95.81
3	True Heading		T displayed if heading is relative to true north.	T
4	Roll	m	Roll in decimal degrees.	+0.60
5	Pitch	m	Pitch in decimal degrees.	+1.05
6	Heave	m	Instantaneous heave in meters.	+0.00
7	Roll Accuracy		Roll standard deviation in decimal degrees.	+0.038
8	Pitch Accuracy		Pitch standard deviation in decimal degrees.	0.035
9	Heading Accuracy		Heading standard deviation in decimal degrees.	0.526
10	GPS Status		GPS Status	0
11	INS Status		INS Status	0

PSTRB

Strobe input time. This message is sent when an assert event occurs on a strobe input pin.

$PSTRB,d,d,d,d*xx\r\n
       1 2 3 4

Index	Field	Units	Description
1	GPS week	weeks	Number of weeks since January 1st of 1980 in GMT
2	timeMsOfWeek	ms	Milliseconds since Sunday morning in GMT
3	pin		Strobe event input pin number
4	count		Strobe event serial index number

INFO

Device version information. Query this message by sending $INFO*0E\r\n.

$INFO,d,d.d.d.d,d.d.d.d,d,d.d.d.d,d,s,YYYY-MM-DD,hh:mm:ss.ms,s*xx\r\n
      1 2       3       4 5       6 7 8          9           10

Index	Field	Units	Description
1	Serial number		Manufacturer serial number
2	Hardware version		Hardware version
3	Firmware version		Firmware version
4	Build number		Firmware build number
5	Protocol version		Communications protocol version
6	Repo revision		Repository revision number
7	Manufacturer		Manufacturer name
8	Build date		Build date: [1] = year, [2] = month, [3] = day
9	Build time		Build date: [0] = hour, [1] = minute, [2] = second, [3] = millisecond
10	Add Info		Additional information
11	Hardware		Hardware: 1=uINS, 2=EVB, 3=IMX, 4=GPX
12	Reserved		Reserved for internal purpose.
13	Build type		Build type: 'a'=ALPHA, 'b'=BETA, 'c'=RELEASE CANDIDATE, 'r'=PRODUCTION RELEASE, 'd'=debug

NMEA Examples

Note

If the command strings below are altered, their checksum must be recalculated.

Note

All NMEA command strings must be followed with a carriage return and new line character (\r\n or 0x0D, 0x0A).

The NMEA string checksum is automatically computed and appended to string when using the InertialSense SDK serialPortWriteAscii function or can be generated using an online NMEA checksum calculator. For example: MTK NMEA checksum calculator

Stop streams on CURRENT port

$STPB*15                                     

Stop all streams on ALL ports

$STPC*14

Query device version information

$INFO*0E

Response:

$INFO,30612,3.1.2.0,1.7.0.0,3522,1.2.74.7,6275,Inertial Sense INC,0018-10-16,23:20:38.41,INL2*58

Stream INS1 @5Hz on port 0

$ASCE,1,3,1*0B

Stream INS1 @400ms on current port

$ASCE,0,3,2*09

Response:

$PINS1,244272.398,2021,427888998,805306448,0.0468,-0.3830,-0.0909,0.232,-0.083,-0.089,40.05574940,-111.65861580,1438.451,-1.678,-5.086,-9.697*11
$PINS1,244272.498,2021,427888998,805306448,0.0469,-0.3830,-0.0902,0.232,-0.081,-0.089,40.05575000,-111.65861550,1438.451,-1.611,-5.060,-9.697*18
$PINS1,244272.598,2021,427888998,805306448,0.0469,-0.3830,-0.0902,0.232,-0.081,-0.089,40.05575022,-111.65861562,1438.449,-1.587,-5.070,-9.695*1e

Stream INS1 @600ms on serial port 1

$ASCE,2,3,3*0A

Response:

$PINS1,256270.627,2021,427888998,1073741912,0.1153,-0.1473,-0.1628,0.001,0.001,0.003,40.05569486,-111.65864500,1416.218,-7.738,-7.570,12.536*3d
$PINS1,256270.647,2021,427888998,1073741912,0.1153,-0.1473,-0.1632,0.001,0.001,0.003,40.05569486,-111.65864500,1416.219,-7.738,-7.570,12.535*32
$PINS1,256270.667,2021,427888998,1073741912,0.1153,-0.1473,-0.1631,0.001,0.001,0.003,40.05569486,-111.65864500,1416.220,-7.738,-7.570,12.534*38

Stream PIMU @400ms and GGA @5Hz on current port

$ASCE,0,6,1,0,2*0D

Response:

$PIMU,3218.543,0.0017,-0.0059,-0.0077,-1.417,-1.106,-9.524,0.0047,0.0031,-0.0069,-1.433,-1.072,-9.585*1f
$GPGGA,231841,4003.3425,N,11139.5188,W,1,29,0.89,1434.16,M,18.82,M,,*59
$GPGGA,231841,4003.3425,N,11139.5188,W,1,29,0.89,1434.19,M,18.82,M,,*56
$PIMU,3218.763,0.0019,-0.0062,-0.0086,-1.426,-1.114,-9.509,0.0054,0.0029,-0.0070,-1.431,-1.085,-9.579*13
$GPGGA,231841,4003.3425,N,11139.5188,W,1,29,0.89,1434.16,M,18.82,M,,*59
$GPGGA,231841,4003.3425,N,11139.5188,W,1,29,0.89,1434.19,M,18.82,M,,*56
$PIMU,3218.543,0.0017,-0.0059,-0.0077,-1.417,-1.106,-9.524,0.0047,0.0031,-0.0069,-1.433,-1.072,-9.585*1f