GUIDE K35 Series Protocol

GUIDE K35 Series exposes standard NMEA 0183 output, RTCM v3.x correction input, and PAIR proprietary commands for embedded-module configuration. Use this reference to review the UART-based data interfaces, query module status, adjust GNSS behavior, and configure serial output.

Protocol scope

NMEA 0183 output Standard positioning sentences for host applications and integration workflows. RTCM v3.x input Correction-data input for RTK positioning workflows. PAIR configuration commands GUIDE K35 Series proprietary query and set commands for module-level configuration.

1. Standard data interfaces

GUIDE K35 Series uses the carrier-board UART0 data path for positioning output, module configuration, and RTCM correction-data input. NTRIP transport is typically handled by the host application; the module consumes the RTCM data stream.

Output interface

NMEA 0183 output

GUIDE K35 Series outputs standard NMEA 0183 positioning sentences through the primary carrier-board UART0 interface. The host application can select sentence types and output intervals with PAIR commands.

Data path: Carrier-board UART0 interface
Default baud rate: 115,200 bps
Supported sentences: GGA, GSA, GSV, RMC, GLL, VTG, and GST
Configuration: Use PAIR050 for the navigation update interval and PAIR062 / PAIR063 for individual sentence output intervals.

Read the NMEA 0183 guide →

Correction interface

RTCM v3.x correction input

GUIDE K35 Series accepts RTCM v3.x correction data for RTK positioning. The host application forwards the correction stream to the module through the carrier-board serial data path.

Protocol: RTCM v3.x
Data path: Host application → carrier-board UART0 → GUIDE K35 Series module
Typical source: An NTRIP client running on the host system
Module role: Consume the RTCM correction stream for RTK processing

Read the RTCM protocol guide →

Carrier-board integration

GUIDE is a surface-mount module rather than an enclosed USB receiver. Route UART0, power, ground, RF, and any required timing or dead-reckoning signals through the carrier board. Review Pin Definitions & Interfaces before finalizing the host connection.

2. PAIR command packet structure

GUIDE K35 Series uses the Airoha AG3335 module platform and exposes its PAIR command set through the carrier-board serial interface. All GUIDE proprietary commands and responses follow the same string format. The maximum length of a command packet is 255 bytes.

$PAIR<Command_ID>[,<Data_Field_1>,...,<Data_Field_N>]*<Checksum><CR><LF>

$PAIR: Proprietary command header.
<Command_ID>: Three-digit numeric command identifier, such as 050.
<Data_Field>: Command-specific parameters separated by commas.
*<Checksum>: 8-bit XOR checksum of all characters between $ and *.
<CR><LF>: Packet terminator in hexadecimal format: 0D 0A.

Persistence note

Configuration changes are not automatically stored across power cycles. Send $PAIR513 after changing persistent settings, then reboot the module or cycle the power supply.

3. PAIR command quick reference

Command	Type	Purpose
System status & control
`PAIR001`	Output	Return the PAIR command execution result.
`PAIR020`	Query	Query firmware release information.
`PAIR024`	Query	Query the GNSS chipset version.
`PAIR004`	Set	Restart using available navigation data stored in NVRAM.
`PAIR005`	Set	Restart without using stored ephemeris data.
`PAIR006`	Set	Restart without using stored navigation data.
`PAIR023`	Set	Reboot the GNSS chipset immediately.
`PAIR513`	Set	Store the current configuration in NVRAM.
`PAIR514`	Set	Clear NVRAM and restore factory defaults.
GNSS configuration
`PAIR066`	Set	Enable or disable satellite constellations.
`PAIR067`	Query	Query the current constellation settings.
`PAIR050`	Set	Set the navigation update interval. K35C is specified for 1 Hz; K35E supports up to 10 Hz.
`PAIR051`	Query	Query the current navigation update interval.
`PAIR031`	Query	Query the WGS84 ECEF XYZ Cartesian velocity vector.
Interface & formatting
`PAIR864`	Set	Configure the UART baud rate.
`PAIR865`	Query	Query the current UART baud rate.
`PAIR062`	Set	Configure the output interval for a selected NMEA sentence.
`PAIR063`	Query	Query the output interval for a selected NMEA sentence.
`PAIR098`	Set	Configure fractional precision for NMEA position values.
`PAIR099`	Query	Query the current NMEA decimal precision mode.
`PAIR100`	Set	Configure the NMEA protocol output mode.
`PAIR101`	Query	Query the current NMEA protocol output mode.

4. Detailed PAIR command dictionary

4.1 System status & control

$PAIR001 - Command acknowledgement

Description

Return the PAIR command execution result.

Type

Output

Return format

$PAIR001,<Command_ID>,<Result>*<Checksum><CR><LF>

Return parameters

Field	Description
`Command_ID`	The three-digit command ID being acknowledged.
`Result`	0: Command successfully sent. 1: Command is processing; wait for the result. 2: Command sending failed. 3: Command ID is not supported. 4: Command parameter error, including out-of-range, missing, or checksum errors. 5: MNL service is busy; retry shortly.

Example

// Host send: cold start
$PAIR006*3C

// Receiver response: success acknowledgement
$PAIR001,006,0*3D

$PAIR020 - Get version

Description

Query firmware release information, hardware and software configuration, and subsystem versions.

Type

Query

Format

$PAIR020*38<CR><LF>

Return format

The module returns a standard acknowledgement packet followed by detailed version information.

$PAIR020,<Project_Version>,<Frequency>,<SW_package>,<Service_version>,<Service_build_time>,<DSP_L1_rom_version>,<DSP_L1_ram_version>,<DSP_L5_rom_version>,<DSP_L5_ram_version>,<Kernel_version>,<Kernel_build_time>,<KF_version>,<KF_build_time>,<RTK_version>,<RTK_build_time>,<Fusion_version>,<Fusion_build_time>*<Checksum><CR><LF>

Return parameters

Field	Description
`Project_Version`	Format: `<Project_board>_<SDK_version>_<SDK_Build_time>` Example: `AG3335A_V1.0.0_YYYYMMDD` The returned project version may vary by GUIDE module variant and firmware release.
`Frequency`	S: Single frequency D: Dual frequency (L1/L5)
`SW_package`	N: Normal W: RAW R: RTK I: NavIC F: Fusion
`Service_version`	MNL service version, seven characters.
`Subsystem versions`	DSP L1 and L5, Kernel, KF, RTK, and Fusion version values. Each version is followed by its build time in `yyMMDDhhmm` format.

Example

// Host send
$PAIR020*38

// Receiver response: placeholder values shown for field structure
$PAIR001,020,0*39
$PAIR020,AG3335A_V1.0.0_YYYYMMDD,D,N,xxxxxxx,yyMMDDhhmm,xx.xxx,xx.xxx,xxxxxxx,yyMMDDhhmm,xxxxxxx,yyMMDDhhmm,xxxxxxx,yyMMDDhhmm,xxxxxxx,yyMMDDhhmm*<Checksum>

$PAIR024 - Get chip version

Description

Query the chipset version.

Type

Query

Format

$PAIR024*3C<CR><LF>

Return format

$PAIR024,<CHIP>*<Checksum><CR><LF>

Return parameters

Field	Description
`CHIP`	Chipset version, such as `A`, `M`, or `S`.

Example

// Host send
$PAIR024*3C

// Receiver response
$PAIR001,024,0*3D
$PAIR024,M*5D

$PAIR004 - Hot start

Description

Restart the module using available navigation data stored in NVRAM.

Type

Set

Format

$PAIR004*3E<CR><LF>

Return format

$PAIR001,004,<Result>*<Checksum><CR><LF>

Example

// Host send
$PAIR004*3E

// Receiver response
$PAIR001,004,0*3F

$PAIR005 - Warm start

Description

Restart the module without using stored ephemeris data.

Type

Set

Format

$PAIR005*3F<CR><LF>

Return format

$PAIR001,005,<Result>*<Checksum><CR><LF>

Example

// Host send
$PAIR005*3F

// Receiver response
$PAIR001,005,0*3E

$PAIR006 - Cold start

Description

Restart the module without using stored position, almanac, or ephemeris data.

Type

Set

Format

$PAIR006*3C<CR><LF>

Return format

$PAIR001,006,<Result>*<Checksum><CR><LF>

Example

// Host send
$PAIR006*3C

// Receiver response
$PAIR001,006,0*3D

$PAIR023 - System reboot

Description

Reboot the GNSS chipset immediately.

Type

Set

Format

$PAIR023*3B<CR><LF>

Return format

None. The module reboots immediately without sending a response.

Example

// Host send
$PAIR023*3B

$PAIR513 - Save settings to NVRAM

Description

Save the current configuration to flash or NVRAM so that changes persist across power cycles.

Type

Set

Format

$PAIR513*3D<CR><LF>

Return format

$PAIR001,513,<Result>*<Checksum><CR><LF>

Example

// Host send
$PAIR513*3D

// Receiver response
$PAIR001,513,0*3C

$PAIR514 - Restore factory defaults

Description

Clear the current user configuration and restore factory defaults.

Type

Set

Format

$PAIR514*3A<CR><LF>

Return format

$PAIR001,514,<Result>*<Checksum><CR><LF>

Example

// Host send
$PAIR514*3A

// Receiver response
$PAIR001,514,0*3B

4.2 GNSS configuration

$PAIR066 - Set GNSS search mode

Description

Enable or disable satellite constellations. The module restarts when it receives this command.

Type

Set

Format

$PAIR066,<GPS>,<GLO>,<GAL>,<BDS>,<QZSS>,<NavIC>*<Checksum><CR><LF>

Parameters

Field	Description
`Constellation flags`	0: Disable 1: Enable

Return format

$PAIR001,066,<Result>*<Checksum><CR><LF>

Example

// Host send: enable GPS, GLONASS, Galileo, BeiDou, and QZSS; disable NavIC
$PAIR066,1,1,1,1,1,0*3B

// Receiver response
$PAIR001,066,0*3B

$PAIR067 - Get GNSS search mode

Description

Query GPS, GLONASS, Galileo, BeiDou, QZSS, and NavIC constellation settings.

Type

Query

Format

$PAIR067*3B<CR><LF>

Return format

$PAIR067,<GPS>,<GLO>,<GAL>,<BDS>,<QZSS>,<NavIC>*<Checksum><CR><LF>

Return parameters

Field	Description
`Constellation flags`	0: Disabled 1: Enabled

Example

// Host send
$PAIR067*3B

// Receiver response
$PAIR001,067,0*3A
$PAIR067,1,0,0,0,0,0*3A

$PAIR050 - Set position fix interval

Description

Set the navigation update interval. When the interval is below 1000 ms, the ASCII NMEA output interval may increase automatically.

Type

Set

GUIDE variant note

GUIDE K35C is specified for a 1 Hz navigation update rate. GUIDE K35E is the RTK + DR variant and supports update intervals down to 100 ms, corresponding to 10 Hz output.

Format

$PAIR050,<Interval_ms>*<Checksum><CR><LF>

Parameters

Field	Description
`Interval_ms`	Position fix interval in milliseconds. Valid range: `100` to `1000`. 1000: 1 Hz, default 200: 5 Hz 100: 10 Hz

Return format

$PAIR001,050,<Result>*<Checksum><CR><LF>

Example

// Host send: set 10 Hz
$PAIR050,100*22

// Receiver response
$PAIR001,050,0*3E

$PAIR051 - Get position fix interval

Description

Query the current position fix interval.

Type

Query

Format

$PAIR051*3E<CR><LF>

Return format

$PAIR051,<Interval_ms>*<Checksum><CR><LF>

Return parameters

Field	Description
`Interval_ms`	Position fix interval in milliseconds.

Example

// Host send
$PAIR051*3E

// Receiver response
$PAIR001,051,0*3F
$PAIR051,1000*13

$PAIR031 - Get 3D velocity

Description

Query the WGS84 ECEF XYZ Cartesian velocity vector in meters per second, with an estimated 1-sigma accuracy.

Type

Query

Format

$PAIR031*38<CR><LF>

Return format

$PAIR031,<VX>,<VY>,<VZ>,<Acc>*<Checksum><CR><LF>

Return parameters

Field	Description
`VX`	WGS84 ECEF X Cartesian velocity vector in m/s.
`VY`	WGS84 ECEF Y Cartesian velocity vector in m/s.
`VZ`	WGS84 ECEF Z Cartesian velocity vector in m/s.
`Acc`	Three-dimensional speed 1-sigma accuracy in m/s.

Example

// Host send
$PAIR031*38

// Receiver response
$PAIR001,031,0*39
$PAIR031,0.19,-0.07,-0.11,0.49*3A

4.3 Interface & formatting

$PAIR864 - Set baud rate

Description

Set the UART baud rate of the GNSS module.

Type

Set

Baud-rate change

The baud-rate change takes effect immediately after the next response. Update the host UART configuration before sending the next command. To keep the change after a power cycle, send $PAIR513 to save the settings, then reboot with $PAIR023 or cycle the power supply.

Format

$PAIR864,<Port_Type>,<Port_Index>,<Baudrate>*<Checksum><CR><LF>

Parameters

Field	Description
`Port_Type`	0: UART
`Port_Index`	0: UART0, main communication port
`Baudrate`	`9600`, `115200` default, `230400`, `460800`, or `921600`.

Return format

$PAIR001,864,<Result>*<Checksum><CR><LF>

Example

// Host send: set UART0 baud rate to 115200
$PAIR864,0,0,115200*1B

// Receiver response: sent at the current baud rate before changing
$PAIR001,864,0*31

$PAIR865 - Get baud rate

Description

Query the UART baud rate of the GNSS module.

Type

Query

Format

$PAIR865,<Port_Type>,<Port_Index>*<Checksum><CR><LF>

Parameters

Field	Description
`Port_Type`	0: UART
`Port_Index`	0: UART0, main communication port

Return format

$PAIR865,<Port_Type>,<Port_Index>,<Baudrate>*<Checksum><CR><LF>

Return parameters

Field	Description
`Baudrate`	Current UART baud rate.

Example

// Host send
$PAIR865,0,0*31

// Receiver response
$PAIR001,865,0*30
$PAIR865,0,0,115200*1A

$PAIR062 - Set NMEA output rate

Description

Configure the output interval of a selected NMEA sentence.

Type

Set

Format

$PAIR062,<Type>,<Output_Rate>*<Checksum><CR><LF>

Parameters

Field	Description
`Type`	-1: Reset all sentences to default 0: NMEA_SEN_GGA 1: NMEA_SEN_GLL 2: NMEA_SEN_GSA 3: NMEA_SEN_GSV 4: NMEA_SEN_RMC 5: NMEA_SEN_VTG 6: NMEA_SEN_ZDA 7: NMEA_SEN_GRS 8: NMEA_SEN_GST
`Output_Rate`	0: Disabled; do not output the sentence. 1: Output once every position fix. 2: Output once every two position fixes. Valid range: `0` to `20`.

Return format

$PAIR001,062,<Result>*<Checksum><CR><LF>

Example

// Host send: disable GSV output
$PAIR062,3,0*3D

// Receiver response
$PAIR001,062,0*3F

$PAIR063 - Get NMEA output rate

Description

Query the output interval of a selected NMEA sentence.

Type

Query

Format

$PAIR063,<Type>*<Checksum><CR><LF>

Parameters

Field	Description
`Type`	NMEA sentence type. Use `-1` to return all configurations or `0` to `8` for a selected sentence.

Return format

$PAIR063,<Type>,<Output_Rate>*<Checksum><CR><LF>

Return parameters

Field	Description
`Output_Rate`	Current output interval setting from `0` to `20`.

Example

// Host send
$PAIR063,0*23

// Receiver response
$PAIR001,063,0*3E
$PAIR063,0,3*3C

$PAIR098 - Set NMEA decimal precision

Description

Configure the number of decimal digits shown in NMEA position values.

Type

Set

Format

$PAIR098,<MODE>*<Checksum><CR><LF>

Parameters

Field	Description
`MODE`	0: Latitude and longitude with four digits; altitude with one digit. 1: Latitude and longitude with five digits; altitude with two digits. 2: Latitude and longitude with six digits; altitude with three digits. 3: Latitude and longitude with seven digits; altitude with three digits.

Return format

$PAIR001,098,<Result>*<Checksum><CR><LF>

Example

// Host send
$PAIR098,0*27

// Receiver response
$PAIR001,098,0*3A

$PAIR099 - Get NMEA decimal precision

Description

Query the current NMEA position precision mode.

Type

Query

Format

$PAIR099*3A<CR><LF>

Return format

$PAIR099,<MODE>*<Checksum><CR><LF>

Return parameters

Field	Description
`MODE`	Current precision mode from `0` to `3`.

Example

// Host send
$PAIR099*3A

// Receiver response
$PAIR001,099,0*3B
$PAIR099,0*26

$PAIR100 - Set NMEA output mode

Description

Configure the NMEA output mode.

Type

Set

Format

$PAIR100,<NMEA_MODE>,<PROPRIETARY_MODE>*<Checksum><CR><LF>

Parameters

Field	Description
`NMEA_MODE`	0: Disable NMEA. 1: ASCII NMEA v4.1, default. 2: ASCII NMEA v3.0.
`PROPRIETARY_MODE`	0: Disable additional proprietary sentences, default. 1: Enable proprietary sentences.

Return format

$PAIR001,100,<Result>*<Checksum><CR><LF>

Example

// Host send: ASCII NMEA v4.1, additional proprietary sentence disabled
$PAIR100,1,0*3A

// Receiver response
$PAIR001,100,0*3A

$PAIR101 - Get NMEA output mode

Description

Query the current NMEA output mode.

Type

Query

Format

$PAIR101*3A<CR><LF>

Return format

$PAIR101,<NMEA_MODE>,<PROPRIETARY_MODE>*<Checksum><CR><LF>

Return parameters

Field	Description
`NMEA_MODE`	Current standard NMEA output mode from `0` to `2`.
`PROPRIETARY_MODE`	Current proprietary sentence output state from `0` to `1`.

Example

// Host send
$PAIR101*3A

// Receiver response
$PAIR001,101,0*3B
$PAIR101,0,1*3B

Integration references

Continue with the GUIDE specifications, carrier-board interface definitions, or the hardware integration overview.

Specifications Review GNSS performance, module interfaces, electrical limits, and physical specifications. Pin Definitions & Interfaces Review the 24-pin LCC assignments, UART interfaces, PPS output, RF input, and carrier-board requirements. Hardware Overview Follow the module-selection, carrier-board interface, and PCB footprint integration path.

Product evaluation

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Review the product page or discuss a module-level integration requirement with the Kalmix team.

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